JP4974183B2 - Photoelectric conversion device - Google Patents

Description

  The present invention relates to a photoelectric conversion device, and more particularly to a photoelectric conversion device having excellent characteristics in a photoelectric conversion device having a configuration using an inversion layer induced by a fixed charge.

  For example, Patent Document 1 includes a first layer made of silicon oxide in direct contact with a semiconductor surface and a second layer made of an insulating material different from the first layer formed on the first layer. A solar cell with a fixed charge contained in the layer is described.

  In the solar cell described in Patent Document 1, an inversion layer is induced on the semiconductor surface by installing a fixed charge at the interface between the first layer and the second layer. By inducing such an inversion layer, it is expected to have higher ultraviolet sensitivity than a normal pn junction doped with impurities.

Patent Document 1 describes that the fixed charge density can be further increased when silicon nitride is used for the second layer, and when different ions such as alkali ions are added to the second layer.
JP-A-55-59784

  However, the solar cell described in Patent Document 1 is excellent because the carrier density in the inversion layer on the semiconductor surface does not increase even when different ions such as alkali ions are added to the second layer made of silicon nitride. There was a problem that a solar cell having the characteristics could not be obtained.

  Accordingly, an object of the present invention is to provide a photoelectric conversion device having excellent characteristics in a photoelectric conversion device having a configuration using an inversion layer induced by a fixed charge.

The present invention includes a semiconductor layer, and the installed dielectric film in contact with the surface of the semiconductor layer, a dielectric film, in the vicinity of the interface with the semiconductor layer, and organic impurities as a positive fixed charge, The semiconductor layer is a photoelectric conversion device made of crystalline silicon, amorphous silicon, or microcrystalline silicon, and the impurity is cesium .

Here, in the photoelectric conversion device of the present invention, the portion where the impurity is most present is a region that is advanced by 5 nm from the interface between the semiconductor layer and the dielectric film toward the semiconductor layer in a direction perpendicular to the interface; preferred you to located in the region between 5nm SusumuMukai regions in the dielectric layer side.

Further, in the photoelectric conversion device of the present invention, at least a partial area of the surface of the semiconductor layer dielectric film is in contact, preferably Rukoto to have a inversion layer or accumulation layer.

In addition, the photoelectric conversion device of the present invention preferably includes an electron collection region in contact with the inversion layer or the accumulation layer.

In the photoelectric conversion device of the present invention, the electron collection region is preferably an n-type region.

In the photoelectric conversion device of the present invention, it is preferable that at least one selected from the group consisting of metal, metal silicide, and a transparent conductive film is provided in at least a part of the n-type region.

In the photoelectric conversion device of the present invention , the electron collection region is preferably at least one selected from the group consisting of metals, metal silicides, and transparent conductive films.

In addition, the photoelectric conversion device of the present invention preferably includes a hole collection region in at least a part of the region of the surface of the semiconductor layer opposite to the side in contact with the dielectric film.

In addition, the photoelectric conversion device of the present invention includes a second dielectric film disposed so as to be in contact with the surface of the semiconductor layer opposite to the side in contact with the dielectric film, and the second dielectric film is connected to the semiconductor layer. It is preferable to have an impurity that becomes a negative fixed charge in the vicinity of the interface.

In the photoelectric conversion device of the present invention, the impurity that becomes a negative fixed charge is selected from the group consisting of boron, aluminum, gallium, indium, platinum, fullerene fluoride, fullerene oxide, fluorine, chlorine, bromine, and iodine. It is preferable to include at least one kind.

In the photoelectric conversion device of the present invention, light is preferably incident from the dielectric film side, and the conductivity type of the semiconductor layer is preferably p-type.

In the photoelectric conversion device of the present invention , light is preferably incident from the side opposite to the dielectric film, and the conductivity type of the semiconductor layer is preferably n-type.

In the photoelectric conversion device of the present invention, the band gap of the dielectric film is preferably 4.2 eV or more.

In the photoelectric conversion device of the present invention, the dielectric film is preferably made of at least one selected from the group consisting of silicon oxide, silicon oxynitride, and silicon nitride.

In the photoelectric conversion device of the present invention, it is preferable that irregularities are formed on the surface of the semiconductor layer.

Further, the present invention includes a first photoelectric conversion layer and a second photoelectric conversion layer, and the first photoelectric conversion layer is in contact with the first semiconductor layer and the surface of the first semiconductor layer. A surface dielectric film having cesium, which is an impurity that is installed and becomes a positive fixed charge in the vicinity of the interface with the first semiconductor layer, and at least a part of the surface region of the first semiconductor layer in contact with the surface dielectric film And a p-type impurity-containing layer having a p-type impurity on the back surface opposite to the surface of the first semiconductor layer, and the second photoelectric conversion layer includes: A second semiconductor layer, an n-type impurity-containing layer having an n-type impurity on the surface of the second semiconductor layer, and a p-type impurity having a p-type impurity on the back surface opposite to the surface of the second semiconductor layer A p-type impurity-containing layer of the first photoelectric conversion layer, and an n-type impurity of the second photoelectric conversion layer. The first semiconductor layer and the second semiconductor layer include crystalline silicon, amorphous silicon, and a stacked structure in which the first photoelectric conversion layer and the second photoelectric conversion layer are stacked by bonding the containing layer. Alternatively, the photoelectric conversion device is made of microcrystalline silicon.

The present invention also provides a first semiconductor layer, a first dielectric film bonded to the surface of the first semiconductor layer, a second dielectric film bonded to the back surface of the first semiconductor layer, And the second semiconductor layer bonded to the back surface of the second dielectric film, and the first dielectric film is an impurity that becomes a positive fixed charge in the vicinity of the interface with the first semiconductor layer. The second dielectric film includes cesium and has an impurity that becomes a negative fixed charge in the vicinity of the interface with the first semiconductor layer and in the vicinity of the interface with the second semiconductor layer. The semiconductor layer and the second semiconductor layer are photoelectric conversion devices made of crystalline silicon, amorphous silicon, or microcrystalline silicon.

In the photoelectric conversion device of the present invention, the impurity that becomes a negative fixed charge is selected from the group consisting of boron, aluminum, gallium, indium, platinum, fullerene fluoride, fullerene oxide, fluorine, chlorine, bromine, and iodine. It is preferable to include at least one kind.

  ADVANTAGE OF THE INVENTION According to this invention, the photoelectric conversion apparatus which has the outstanding characteristic in the photoelectric conversion apparatus of the structure using the inversion layer induced by the fixed charge can be provided.

  Embodiments of the present invention will be described below. In the drawings of the present invention, the same reference numerals represent the same or corresponding parts.

  In the present invention, the inversion layer is an electron carrier layer on the surface of the p-type semiconductor, a hole carrier layer on the surface of the n-type semiconductor layer, or i-type induced by an impurity that becomes a fixed charge in the dielectric film. (Intrinsic type) Including the case of an electron carrier layer or a hole carrier layer on a semiconductor surface.

  In the embodiment of the present invention, the n-type layer and the p-type layer are formed by doping impurities into the same semiconductor material as the semiconductor layer, but a semiconductor material different from the semiconductor layer may be used. For example, when amorphous silicon is used as the semiconductor layer, amorphous silicon germanium doped with n-type or p-type impurities, amorphous silicon carbide, or the like can be used as the n-type layer or p-type layer.

In the embodiment of the present invention, the case where silicon is mainly used as the semiconductor layer will be mainly described. However, as the semiconductor layer, in addition to silicon, gallium nitride, silicon carbide, cadmium tellurium, gallium arsenide, indium phosphide Cu (In, Ga) Se ₂ , silicon germanium, germanium, or the like can also be used.

<Embodiment 1>
FIG. 1A is a schematic plan view of the surface on the light incident side of an example of the photoelectric conversion device of the present invention. Here, a silicon oxide film 6 as a dielectric film is provided on the surface on the light incident side of the photoelectric conversion device of the present embodiment having the configuration shown in FIG. A comb-shaped n + layer 3 as an impurity-containing layer is formed below the silicon oxide film 6, and a band-shaped metal electrode 8 is formed as a surface electrode in contact with the comb-shaped n + layer 3. .

  1B shows a schematic cross section along 1b-1b in FIG. 1A, and FIG. 1C shows a schematic cross section along 1c-1c in FIG. 1A. . As shown in FIGS. 1B and 1C, in the photoelectric conversion device of the present embodiment, the n + layer 3 is formed on the light incident side surface of a p-type silicon substrate 2 as a semiconductor layer. Is formed. A p + layer 1 is formed on the back surface of the p-type silicon substrate 2 opposite to the light incident side surface, and a back electrode 7 is formed so as to be in contact with the back surface of the p + layer 1. ing. The p + layer 1 is a layer containing p-type impurities at a higher concentration than the p-type silicon substrate 2.

  Furthermore, the silicon oxide film 6 is formed so as to cover the surface of the p-type silicon substrate 2 on the light incident side. The silicon oxide film 6 has cesium 5 as an impurity that becomes a positive fixed charge at the interface with the light incident side surface of the p-type silicon substrate 2.

  Here, since the cesium 5 is ionized in the vicinity of the interface with the surface on the light incident side of the p-type silicon substrate 2 and becomes a positive fixed charge, the light incident on the p-type silicon substrate 2 in contact with the silicon oxide film 6. A surface inversion layer 4 that functions as an n-type semiconductor is induced in at least a partial region of the surface on the side in the same manner as the n + layer 3.

Instead of the p-type silicon substrate 2, an intrinsic type silicon substrate may be used.
Hereinafter, an example of a method for manufacturing the photoelectric conversion device of the present embodiment having the configuration shown in FIG. 1 will be described. First, the silicon oxide film 6 is formed on the light incident surface of the p-type silicon substrate 2. Here, when the p-type silicon substrate 2 is made of single crystal silicon, the light of the p-type silicon substrate 2 is thermally oxidized at a temperature of, for example, 800 ° C. to 1200 ° C., preferably at a temperature of 900 ° C. to 1050 ° C. A silicon oxide film 6 can be formed on the incident-side surface. The silicon oxide film 6 may be formed by using, for example, a CVD (Chemical Vapor Deposition) method or an ALD (Atomic Layer Deposition) method. Further, by forming the silicon oxide film 6 using the plasma CVD method, the silicon oxide film 6 can be formed at a low temperature such as 400 ° C. or lower.

Next, the p + layer 1 is formed on the back surface of the p-type silicon substrate 2. Here, the formation of the p + layer 1 can be performed, for example, by diffusing p-type impurities on the back surface of the p-type silicon substrate 2. The p-type impurity can be diffused by vapor phase diffusion using a gas containing a p-type impurity (boron) such as BBr ₃ . In addition to boron, for example, aluminum or indium can be used as the p-type impurity. The p + layer 1 can also be formed by annealing after introducing a p-type impurity into the back surface of the p-type silicon substrate 2 by using, for example, an ion implantation method or an ion doping method.

Next, the n + layer 3 is formed on the light incident side surface of the p-type silicon substrate 2. Here, the formation of the n + layer 3 can be performed by diffusing n-type impurities on the surface of the p-type silicon substrate 2 on the light incident side. The n-type impurity is diffused by, for example, providing an opening in a part of the silicon oxide film 6 at a location corresponding to the location where the n + layer 3 is formed, and an n-type impurity (phosphorus) such as POCl ₃ from the opening. It can be performed by vapor phase diffusion using a gas containing. In addition to phosphorus, for example, arsenic or antimony can be used as the n-type impurity. The n + layer 3 can also be formed by annealing after introducing an n-type impurity into the surface of the p-type silicon substrate 2 using, for example, an ion implantation method or an ion doping method.

  Next, cesium 5 is contained in the silicon oxide film 6 formed on the light incident side surface of the p-type silicon substrate 2. Here, the cesium 5 includes, for example, cesium 5 in the silicon oxide film 6 by ion-implanting cesium ions into the silicon oxide film 6 formed on the light incident side surface of the p-type silicon substrate 2. Can do.

  Next, the p-type silicon substrate 2 is annealed. Here, annealing of the p-type silicon substrate 2 can be performed, for example, by annealing the p-type silicon substrate 2 after the cesium ion implantation at a temperature of, for example, 800 ° C. to 1000 ° C. Thereby, cesium 5 in the silicon oxide film 6 can be segregated at the interface with the surface of the p-type silicon substrate 2 on the light incident side. Since the cesium 5 segregated at the interface between the silicon oxide film 6 and the p-type silicon substrate 2 is positively charged and ionized by releasing electrons to the p-type silicon substrate 2, the p-type silicon substrate in contact with the silicon oxide film 6 is used. The surface inversion layer 4 is formed on the surface of the light incident side 2.

  Next, the metal electrode 8 is formed on the light incident side surface of the p-type silicon substrate 2. Here, the metal electrode 8 is formed, for example, by providing an opening at a location of the silicon oxide film 6 corresponding to the location where the metal electrode 8 is formed, and depositing metal in a predetermined shape using a mask or the like. can do.

  Next, a back electrode 7 is formed on the back surface of the p + layer 1 of the p-type silicon substrate 2. Here, the back electrode 7 can be formed, for example, by evaporating metal on the back surface of the p + layer 1 of the p-type silicon substrate 2.

  Finally, by annealing the p-type silicon substrate 2 after the formation of the metal electrode 8 and the back electrode 7, an example of the photoelectric conversion device of the present embodiment having the above-described configuration is manufactured. Here, annealing of the p-type silicon substrate 2 can be performed by exposing the p-type silicon substrate 2 to a hydrogen atmosphere at a temperature of 350 ° C. to 500 ° C., for example.

  In the photoelectric conversion device of the present embodiment having the above-described configuration manufactured as described above, the silicon oxide film 6 and the surface on the light incident side of the p-type silicon substrate 2 are in contact with each other, and the p-type of the silicon oxide film 6 is formed. The surface inversion layer 4 is formed on the light incident side surface of the p-type silicon substrate 2 by cesium ionized at the interface with the light incident side surface of the silicon substrate 2.

  Therefore, in the photoelectric conversion device according to the present embodiment having the above-described configuration, it is described in Patent Document 1 in which a first layer that does not include a fixed charge is provided between a second layer that includes a fixed charge and a semiconductor surface. Compared to the solar cell, negative charges are more easily induced in the surface inversion layer 4 at a high density, the function as an n-type semiconductor is enhanced, and the recombination of carriers on the light incident side surface of the p-type silicon substrate 2 is suppressed. This improves the characteristics of the photoelectric conversion device such as the photoelectric conversion efficiency.

  Further, by providing the surface inversion layer 4 functioning as an n-type semiconductor instead of the n + layer 3 serving as an absorption source of short-wavelength light on the light incident side surface of the p-type silicon substrate 2, short-wavelength light is provided. Therefore, the characteristics of the photoelectric conversion device such as the photoelectric conversion efficiency can be further improved.

  Further, in the photoelectric conversion device of the present embodiment having the above-described configuration, the negative polarity induced in the surface inversion layer 4 by the segregation amount of cesium at the interface between the silicon oxide film 6 and the light incident side surface of the p-type silicon substrate 2. Charge (electron) density can be controlled.

  In particular, when cesium is segregated at the interface between the silicon oxide film 6 and the p-type silicon substrate 2 by cesium ion implantation into the silicon oxide film 6 and annealing as in the present embodiment, an optimum negative in the surface inversion layer 4 is obtained. Since the margin of the cesium ion implantation amount for obtaining the charge density is wide, a photoelectric conversion device with stable quality and high characteristics can be provided.

  In the photoelectric conversion device of the present embodiment configured as described above, the interface state on the light incident side surface of the p-type silicon substrate 2 is terminated with a negative charge induced in the surface inversion layer 4, thereby forming the p-type. Recombination of carriers at the interface state on the light incident surface of the silicon substrate 2 is suppressed, and characteristics of the photoelectric conversion device such as photoelectric conversion efficiency can be further improved.

  In the above description, the p-type silicon substrate 2 is used as the semiconductor layer. However, the present invention is not limited to this. For example, a semiconductor layer such as crystalline silicon, amorphous silicon, microcrystalline silicon, or another type of semiconductor other than silicon is used. It may be used. Note that crystalline silicon includes single crystal silicon, polycrystalline silicon, a mixture of single crystal silicon and polycrystalline silicon, or the like.

  In the above description, the p-type silicon substrate 2 is made of single crystal silicon. However, when a semiconductor layer made of, for example, amorphous silicon is used instead of the p-type silicon substrate 2, an oxide containing cesium 5 is used. After the silicon film 6 is formed, it is preferable to manufacture the photoelectric conversion device of the present embodiment without performing a high-temperature process.

  In the above description, the silicon oxide film 6 is used as the dielectric film. However, it is needless to say that the dielectric film is not limited thereto. For example, at least one selected from the group consisting of silicon oxide, silicon oxynitride, and silicon nitride is used. It may be used.

  Further, as the dielectric film, it is preferable to use a dielectric film having a band gap of 4.2 eV or more. For example, since most of sunlight is composed of light having a wavelength of 300 nm or more, when sunlight is incident using a dielectric film having a band gap of 4.2 eV or more, a wavelength of 300 nm or more is used. Since the solar light having a thickness is suppressed from being absorbed by the dielectric film and the conversion loss is reduced, the characteristics of the photoelectric conversion device tend to be further improved.

  Moreover, in the above, although the case where cesium 5 was used as an impurity which becomes a positive fixed charge was described, it is not limited to this, for example, lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, One containing at least one selected from the group consisting of barium, phosphorus, arsenic and antimony can be used.

  In the photoelectric conversion device of this embodiment having the above structure, the p-type and n-type conductivity types may be interchanged. In this case, an impurity that becomes a negative fixed charge can be used instead of an impurity that becomes a positive fixed charge such as cesium. Examples of the impurity that becomes a negative fixed charge include those containing at least one selected from the group consisting of boron, aluminum, gallium, indium, platinum, fullerene fluoride, fullerene oxide, fluorine, chlorine, bromine, and iodine. Can be used.

  Note that the impurity that becomes a positive fixed charge and the impurity that becomes a negative fixed charge may each be included in an oxide state.

  Further, in the photoelectric conversion device of the present embodiment having the above-described configuration, the location where the most impurities are present is from the interface between the p-type silicon substrate 2 as the semiconductor layer and the silicon oxide film 6 as the dielectric film. Positioned in a region between a region advanced 5 nm toward the p-type silicon substrate 2 as a semiconductor layer and a region advanced 5 nm toward the silicon oxide film 6 as a dielectric film in a direction perpendicular to the interface It is preferable to do. In this case, the characteristics of the photoelectric conversion device of the present embodiment having the above configuration tend to be further improved.

  In other words, in the photoelectric conversion device of this embodiment, the dielectric film may have an impurity that becomes a positive or negative fixed charge in the vicinity of the interface with the semiconductor layer. Is present in a region between the region of the semiconductor layer and the dielectric film that is advanced by 5 nm toward the semiconductor layer in the direction perpendicular to the interface and the region that is advanced by 5 nm toward the dielectric film. If you do.

  In the above, the silicon oxide film 6 on the light incident side of the p-type silicon substrate 2 may function as an antireflection film, and a texture structure and / or a moth-eye structure is formed on the surface of the silicon oxide film 6. Needless to say.

  Further, as described above, in the photoelectric conversion device of the present embodiment having the above-described configuration, the n-type and p-type conductivity types may be interchanged. Note that when the n-type and p-type conductivity types are interchanged in the photoelectric conversion device of the present embodiment having the above-described configuration, the polarities of the positive and negative charges are also interchanged.

  Further, in the photoelectric conversion device of the present embodiment having the above configuration, the p + layer 1 need not be formed.

<Embodiment 2>
FIG. 2A is a schematic plan view of the surface on the light incident side of another example of the photoelectric conversion device of the present invention. FIG. 2B shows a schematic cross section taken along 2b-2b in FIG. 2A, and FIG. 2C shows a schematic cross section taken along 2c-2c in FIG. Show.

  Here, in the photoelectric conversion device of the present embodiment configured as shown in FIGS. 2A to 2C, the electrode in contact with the n + layer 3 on the entire surface on the light incident side of the p-type silicon substrate 2. Is characterized in that a transparent conductive film 9 is formed.

  By adopting the configuration as in the present embodiment, light can be incident from the entire surface on the light incident side of the p-type silicon substrate 2, and the photoelectric conversion efficiency of the photoelectric conversion device by reducing the resistance of the electrode, etc. It becomes possible to further improve the characteristics. In addition, since the electrode patterning step and the electrode patterning mask are not required, the manufacturing cost can be reduced and the manufacturing efficiency can be improved.

  As the transparent conductive film 9, for example, a single layer made of ITO (Indium Tin Oxide), IO (Indium Oxide), TO (Tin Oxide) or ZO (Zinc Oxide) is used. Alternatively, a multi-layer stack can be used.

  The transparent conductive film 9 is provided with an opening in a part of the silicon oxide film 6 so that at least a part of the n + layer 3 is exposed, and the transparent conductive film 9 made of ITO, IO, TO, ZO, or the like. Can be formed by vapor deposition or the like so as to cover from above.

  Since the description other than the above in the present embodiment is the same as that in the first embodiment, the description thereof is omitted here.

<Embodiment 3>
FIG. 3A is a schematic plan view of the surface on the light incident side of another example of the photoelectric conversion device of the present invention. FIG. 3B shows a schematic cross section taken along 3b-3b in FIG. 3A, and FIG. 3C shows a schematic cross section taken along 3c-3c in FIG. Show.

  Here, in the photoelectric conversion device of the present embodiment having the configuration shown in FIGS. 3A to 3C, the surface of the p-type silicon substrate 2 on the light incident side is an electrode in contact with the n + layer 3. It is characterized in that the transparent conductive film 9 is formed in a comb shape.

  With the configuration as in the present embodiment, the area of the surface of the transparent conductive film 9 formed on the light incident side surface of the p-type silicon substrate 2 can be reduced. Reflection and absorption of light can be suppressed. Thereby, in the photoelectric conversion apparatus of this Embodiment, compared with the photoelectric conversion apparatus of the structure of Embodiment 2, the improvement of characteristics, such as photoelectric conversion efficiency, can further be improved.

  Since the description other than the above in the present embodiment is the same as that in the first and second embodiments, the description thereof is omitted here.

<Embodiment 4>
FIG. 4A is a schematic plan view of the surface on the light incident side of another example of the photoelectric conversion device of the present invention. 4B shows a schematic cross section taken along 4b-4b in FIG. 4A, and FIG. 4C shows a schematic cross section taken along 4c-4c in FIG. 4A. Show.

  Here, in the photoelectric conversion device of the present embodiment having the configuration shown in FIGS. 4A to 4C, a comb is formed as an electrode in contact with the n + layer 3 on the light incident side surface of the p-type silicon substrate 2. It is characterized in that a shaped metal silicide 10 is formed.

  By adopting the configuration of the present embodiment, the comb-shaped metal silicide 10 is formed on the surface of the comb-shaped n + layer 3 by using a conventionally known self-aligned silicidation (SALICIDE) process. This eliminates the need for an electrode patterning step and an electrode patterning mask, thereby reducing manufacturing costs and improving manufacturing efficiency.

The metal silicide 10 is not particularly limited as long as it is made of a compound of at least one arbitrary metal and silicon. For example, titanium silicide (TiSi _x (x≈0.5 to 2)), erbium silicide (ErSi _x (x≈0.5 to 2)), ytterbium silicide (YbSi _x (x≈0.5 to 2)), platinum silicide (PtSi _x (x≈0.5 to 1)) ), nickel silicide _{(Ni x Si (x ≒ 0.5~2} )) or cobalt silicide _{(Co x Si (x ≒ 0.5~2} )) or the like can be used. Even when a low temperature process is required as in the case of using amorphous silicon or the like instead of the p-type silicon substrate 2, Ni _x Si (x≈1-2), Co _x Si (x≈1) By using ~ 2), it is possible to form the metal silicide 10 at a low temperature of, for example, 400 ° C. or lower.

  Since the description other than the above in the present embodiment is the same as that in the first to third embodiments, the description thereof is omitted here.

<Embodiment 5>
FIG. 5 shows a schematic cross-sectional view of another example of the photoelectric conversion device of the present invention. In the photoelectric conversion device of this embodiment having the configuration shown in FIG. 5, the first photoelectric conversion layer 51, the second photoelectric conversion layer 52, and the third photoelectric conversion layer 53 are arranged in this order from the light incident side. It has a laminated structure.

  Here, the first photoelectric conversion layer 51 is disposed so as to be in contact with the first amorphous silicon layer 2a as the first semiconductor layer and the light incident side surface of the first amorphous silicon layer 2a. And a silicon oxide film 6 as a surface dielectric film which is a body film.

  The silicon oxide film 6 has cesium 5 as an impurity that becomes a positive fixed charge in the vicinity of the interface with the first amorphous silicon layer 2a. Here, since the cesium 5 is ionized in the vicinity of the interface with the light incident side surface of the first amorphous silicon layer 2a and becomes a positive fixed charge, the first amorphous silicon layer in contact with the silicon oxide film 6 is used. A surface inversion layer 4 functioning as an n-type semiconductor is induced in at least a partial region of the light incident side surface 2a.

  The first amorphous silicon layer 2a has a first impurity having a conductivity type opposite to that of the surface inversion layer 4 on the back surface, which is the surface opposite to the light incident surface (in the present embodiment). Is formed as a first impurity-containing layer having p-type impurities).

  The second photoelectric conversion layer 52 has a second amorphous silicon layer 2b as a second semiconductor layer.

  Here, the second amorphous silicon layer 2b has a second impurity having a conductivity type opposite to the first impurity (in this embodiment, an n-type impurity) on the light incident side surface. An n + layer 3 is formed as an impurity-containing layer.

  Further, on the back surface of the second amorphous silicon layer 2b opposite to the surface on the light incident side, a third impurity having a conductivity type opposite to the second impurity (in the present embodiment) Is formed as a third impurity-containing layer having p-type impurities).

  The third photoelectric conversion layer 53 has a third amorphous silicon layer 2c as a third semiconductor layer.

  Here, the surface on the light incident side of the third amorphous silicon layer 2c has a fourth impurity having a conductivity type opposite to the third impurity (n-type impurity in the present embodiment). 4 is formed as an impurity-containing layer 4.

  Further, on the back surface, which is the surface opposite to the light incident surface of the third amorphous silicon layer 2c, a fifth impurity having a conductivity type opposite to the fourth impurity (in the present embodiment). Is formed as a fifth impurity-containing layer having p-type impurities).

  Then, the p + layer 1 formed on the back surface opposite to the light incident side surface of the first photoelectric conversion layer 51 and the light incident side surface of the second photoelectric conversion layer 52 are formed. The n + layer 3 thus formed is joined. Further, the p + layer 1 formed on the back surface opposite to the light incident side surface of the second photoelectric conversion layer 52 and the light incident side surface of the third photoelectric conversion layer 53 are formed. The n + layer 3 thus formed is joined. These junctions constitute a stacked structure in which the first photoelectric conversion layer 51, the second photoelectric conversion layer 52, and the third photoelectric conversion layer 53 are stacked in this order from the light incident side.

  In addition, a transparent conductive film 9 as a surface electrode is formed so as to be in contact with a part of the light incident side surface of the first amorphous silicon layer 2a of the first photoelectric conversion layer 51 having the above-described stacked structure, A back electrode 7 made of, for example, aluminum is formed so as to be in contact with the p + layer 1 on the back surface of the third amorphous silicon layer 2c of the third photoelectric conversion layer 53 having the above laminated structure. Here, the transparent conductive film 9 is in contact with the light incident side surface of the first amorphous silicon layer 2 a through the opening formed in the silicon oxide film 6.

  Note that it is difficult to achieve conduction by a Schottky barrier at most contact portions between the transparent conductive film 9 and the first amorphous silicon layer 2a, and it is difficult to take out carriers generated by the photoelectric conversion device. However, the edge portion 11 that is the end portion of the transparent conductive film 9 that is in contact with the light incident side surface of the first amorphous silicon layer 2a is in contact with the surface inversion layer 4, and the edge portion 11 has a Schottky barrier modulation effect. Since the barrier is reduced and the contact resistance is reduced to enable ohmic connection, carriers generated by the photoelectric conversion device can be taken out more easily.

  Hereinafter, an example of a method for manufacturing the photoelectric conversion device of the present embodiment having the configuration shown in FIG. 5 will be described. First, the third photoelectric conversion layer 53 is formed on the surface of the back electrode 7. Here, the third photoelectric conversion layer 53 is formed by forming a p-type amorphous silicon film doped with p-type impurities on the surface of the back electrode 7 by, for example, a CVD (Chemical Vapor Deposition) method. 1 is formed, the doping of the p-type impurity is stopped, a non-doped amorphous silicon film is formed to form a third amorphous silicon layer 2c, and an n-type amorphous silicon film doped with an n-type impurity is further formed. It can be formed by forming the n + layer 3.

  The p-type amorphous silicon film is formed by doping the p-type impurity by, for example, forming the amorphous silicon film in a state where a doping gas containing the p-type impurity is mixed in the raw material gas of the amorphous silicon film. it can. For example, boron, indium, or aluminum can be used as the p-type impurity.

  Further, the formation of the n-type amorphous silicon film by doping with the n-type impurity can be performed, for example, by forming the amorphous silicon film in a state where a doping gas containing the n-type impurity is mixed in the raw material gas of the amorphous silicon film. it can. For example, phosphorus, arsenic, or antimony can be used as the n-type impurity.

  Note that the third photoelectric conversion layer 53 is made of amorphous silicon having an nip structure, but p-type single crystal or polycrystalline silicon having an n + layer formed on the surface may be used. In this case, the conversion efficiency is further improved.

  Next, the second photoelectric conversion layer 52 is formed on the surface of the third photoelectric conversion layer 53. Here, as with the third photoelectric conversion layer 53, the second photoelectric conversion layer 52 is also a p-type doped with a p-type impurity on the surface of the third photoelectric conversion layer 53 by, for example, a CVD method or the like. After forming the amorphous silicon film and forming the p + layer 1, the doping of the p-type impurity is stopped to form a non-doped amorphous silicon film to form the second amorphous silicon layer 2b, and further, the n-type impurity Can be formed by forming an n + layer 3 by forming an n-type amorphous silicon film doped with.

  Next, the first photoelectric conversion layer 51 is formed on the surface of the second photoelectric conversion layer 52. Here, the 1st photoelectric converting layer 51 can be formed as follows, for example. First, a p-type amorphous silicon film doped with a p-type impurity is formed on the surface of the second photoelectric conversion layer 52 by CVD or the like to form the p + layer 1, and then doped with a p-type impurity. Stop and form a non-doped amorphous silicon film to form a first amorphous silicon layer 2a. Thereafter, the first photoelectric conversion layer 51 can be formed by forming the silicon oxide film 6 containing cesium 5 on the surface of the first amorphous silicon layer 2a.

  Here, the silicon oxide film 6 containing cesium 5 can be formed, for example, by introducing a gas containing cesium such as cesium vapor together with a silicon oxide raw material in a CVD method. The cesium 5 is formed by ion-implanting cesium 5 into the silicon oxide film 6 by ion-implanting cesium ions into the silicon oxide film 6 formed on the light incident side surface of the first amorphous silicon layer 2a. It can be included. Further, a solution containing cesium such as an aqueous cesium chloride solution or an aqueous cesium hydroxide solution is applied to the surface of the amorphous silicon layer 2a and dried, and then the silicon oxide film 6 is formed by, for example, a CVD method, thereby forming an amorphous film. Cesium 5 can be disposed in the vicinity of the interface between the silicon layer 2 a and the silicon oxide film 6.

  Finally, by forming the transparent conductive film 9 on the light incident side surface of the first photoelectric conversion layer 51, the photoelectric conversion device of the present embodiment having the configuration shown in FIG. 5 is manufactured. Here, the transparent conductive film 9 is provided with an opening in a part of the silicon oxide film 6 so that at least a part of the light incident side surface of the first amorphous silicon layer 2a is exposed, for example, ITO, IO, The transparent conductive film 9 made of TO or ZO can be formed by sputtering or vapor deposition so as to cover it.

  In the photoelectric conversion device of the present embodiment having the above-described configuration manufactured as described above, the silicon oxide film 6 and the surface on the light incident side of the first amorphous silicon layer 2a are in contact with each other. The surface inversion layer 4 is formed on the light incident side surface of the first amorphous silicon layer 2a by cesium ionized at the interface with the light incident side surface of the first amorphous silicon layer 2a.

  Therefore, in the photoelectric conversion device according to the present embodiment having the above-described configuration, it is described in Patent Document 1 in which a first layer that does not include a fixed charge is provided between a second layer that includes a fixed charge and a semiconductor surface. Compared with the solar cell, negative charges are more easily induced in the surface inversion layer 4, the function as an n-type semiconductor is enhanced, and recombination of carriers on the light incident side surface of the first amorphous silicon layer 2 a is suppressed. As a result, the characteristics of the photoelectric conversion device such as the photoelectric conversion efficiency are improved.

  Further, by providing the surface inversion layer 4 functioning as an n-type semiconductor in place of the n + layer serving as the short wavelength light absorption source on the light incident side surface of the first amorphous silicon layer 2a, Since light absorption is suppressed as compared with the n + layer, characteristics of the photoelectric conversion device such as photoelectric conversion efficiency can be further improved.

  Further, in the photoelectric conversion device of the present embodiment having the above configuration, the surface inversion layer 4 is induced by the segregation amount of cesium at the interface between the silicon oxide film 6 and the surface of the first amorphous silicon layer 2a on the light incident side. The negative charge density can be controlled.

  Further, in the photoelectric conversion device of the present embodiment configured as described above, by terminating the interface state on the light incident side surface of the first amorphous silicon layer 2a with the negative charge induced in the surface inversion layer 4, Recombination of carriers at the interface state on the light incident side surface of the first amorphous silicon layer 2a is suppressed, and characteristics of the photoelectric conversion device such as photoelectric conversion efficiency can be further improved.

  Further, when amorphous silicon is used for the semiconductor layer in contact with the surface electrode as in the photoelectric conversion device of this embodiment mode, since the activation rate of the impurity is low, the semiconductor layer in contact with the surface electrode has a high concentration. However, in the photoelectric conversion device of the present embodiment having the above-described configuration, the surface inversion layer 4 is formed on the surface of the first amorphous silicon layer 2a by the ionized cesium in the silicon oxide film 6. Since the surface inversion layer 4 and the transparent conductive film 9 can be brought into contact with each other, it is not necessary to form a high concentration impurity doped layer.

  In the above description, amorphous silicon is used for each of the first semiconductor layer, the second semiconductor layer, and the third semiconductor layer. However, the present invention is not limited thereto, and the first semiconductor layer and the second semiconductor layer are not limited thereto. As the third semiconductor layer, for example, a semiconductor layer such as crystalline silicon, amorphous silicon, microcrystalline silicon, or another type of semiconductor other than silicon may be used. Note that crystalline silicon includes single crystal silicon, polycrystalline silicon, a mixture of single crystal silicon and polycrystalline silicon, or the like.

  In the case where crystalline silicon is used for each of the first semiconductor layer, the second semiconductor layer, and the third semiconductor layer, the first photoelectric conversion layer 51, the second photoelectric conversion layer 52, and the third photoelectric layer are used. The laminated structure with the conversion layer 53 can be manufactured as follows, for example. First, a p + layer 1 is formed by diffusing a p-type impurity on one surface of crystalline silicon, and a silicon substrate (double-sided doped) is formed by diffusing an n-type impurity on the other surface of crystalline silicon. Two silicon substrates) are produced, and p-type impurities are diffused only on one surface of the crystalline silicon to form the p + layer 1, and n-type impurities are not diffused on the other surface of the crystalline silicon. A silicon substrate (one-side doped silicon substrate) on which the + layer 3 is not formed is produced. Then, the n + layer 3 of one double-sided doped silicon substrate is bonded to the p + layer 1 of the single-sided doped silicon substrate, and the n + layer of another double-sided doped silicon substrate is bonded to the p + layer 1 of the double-sided doped silicon substrate. By laminating 3, the above laminated structure can be produced.

  Then, after cesium 5 is arranged on the surface of the exposed single-sided doped silicon substrate, for example, by a thermal oxidation method, a CVD method, an ALD method, an RTO (Rapid Thermal Oxidation) method, a plasma oxidation method, or the like. A silicon oxide film 6 is formed on a part of the exposed surface of the single-side doped silicon substrate. Subsequently, the transparent conductive film 9 made of ITO, IO, TO, ZO or the like is formed by using, for example, a sputtering method, a CVD method, or a sol-gel method, and the laminated structure on the opposite side to the transparent conductive film 9 is formed. The photoelectric conversion device of the present embodiment can be manufactured by forming the back electrode 7 in contact with the p-type layer on the back surface. The cesium 5 may be segregated at the interface between the silicon oxide film 6 and the one-side doped silicon substrate by forming a silicon oxide film 6 and then implanting cesium ions into the silicon oxide film 6 and then annealing. Good.

  As described above, when the cesium 5 ionized in the vicinity of the interface between the silicon oxide film 6 and the first semiconductor layer is annealed by annealing the silicon oxide film 6, cesium for obtaining an optimum electron density in the surface inversion layer 4. Since the margin of the ion implantation amount is wide, a photoelectric conversion device with stable quality and high characteristics can be provided. In addition, after forming a silicon oxide film 6 thicker than a desired film thickness, cesium ions are ion-implanted into the silicon oxide film 6 and then annealed to thereby change the cesium between the silicon oxide film 6 and the one-side doped silicon substrate. The silicon oxide film 6 may be thinned until it has a desired thickness by segregating at the interface and then performing treatment with a hydrofluoric acid solution or reactive ion etching.

  In the photoelectric conversion device of this embodiment having the above structure, the band gap of the first semiconductor layer close to the light incident side is preferably equal to or larger than the band gap of the second semiconductor layer far from the light incident side. More preferably, the band gap of the second semiconductor layer close to the light incident side is equal to or greater than the band gap of the third semiconductor layer far from the light incident side. Further, the band gap of the first semiconductor layer close to the light incident side is equal to or larger than the band gap of the second semiconductor layer far from the light incident side, and the band gap of the second semiconductor layer close to the light incident side is light. More preferably, it is equal to or greater than the band gap of the third semiconductor layer far from the incident side (the band gap of the third semiconductor layer ≦ the band gap of the second semiconductor layer ≦ the band gap of the first semiconductor layer). By adopting such a stacked structure that can sequentially absorb short-wavelength light from long-wavelength light from the light incident side, the amount of light incident on the photoelectric conversion device of this embodiment is increased. The characteristics of the photoelectric conversion device of this embodiment such as conversion efficiency tend to be improved.

  In addition, as a structure of the semiconductor layer for satisfying the relationship of the band gap of the third semiconductor layer ≦ the band gap of the second semiconductor layer ≦ the band gap of the first semiconductor layer, for example, the first semiconductor layer For example, amorphous silicon carbide (SiC) is used for the second semiconductor layer, amorphous silicon is used for the second semiconductor layer, and microcrystalline silicon is used for the third semiconductor layer.

  As another configuration of the semiconductor layer for satisfying the relationship of the band gap of the third semiconductor layer ≦ the band gap of the second semiconductor layer ≦ the band gap of the first semiconductor layer, for example, A configuration in which amorphous silicon carbide is used for the semiconductor layer, amorphous silicon is used for the second semiconductor layer, and amorphous silicon germanium (SiGe) is used for the third semiconductor layer can be given.

  The thickness of the first semiconductor layer is preferably thinner than the carrier diffusion length in the first semiconductor layer. In this case, the recombination of carriers in the first semiconductor layer can be effectively suppressed, and the probability that incident light is absorbed by using the stacked structure as in this embodiment will also be increased. Can be high.

  The thickness of the second semiconductor layer is preferably thinner than the carrier diffusion length in the second semiconductor layer. In this case, the recombination of carriers in the second semiconductor layer can be effectively suppressed, and the probability that incident light is absorbed by using the stacked structure as in this embodiment will also be increased. Can be high.

  The thickness of the third semiconductor layer is preferably thinner than the carrier diffusion length in the third semiconductor layer. In this case, the recombination of carriers in the third semiconductor layer can be effectively suppressed, and the probability that incident light is absorbed by the stacked structure as in this embodiment will also be obtained. Can be high.

  In the above description, the silicon oxide film 6 is used as the surface dielectric film. However, the present invention is not limited to this. For example, at least one selected from the group consisting of silicon oxide, silicon oxynitride, and silicon nitride is used. May be used.

  As the surface dielectric film, it is preferable to use a dielectric film having a band gap of 4.2 eV or more. For example, since most of sunlight is composed of light having a wavelength of 300 nm or more, when sunlight is incident using a surface dielectric film having a band gap of 4.2 eV or more, it is 300 nm or more. Since sunlight having a wavelength is suppressed from being absorbed by the dielectric film and conversion loss is reduced, characteristics of the photoelectric conversion device tend to be further improved.

  Moreover, in the above, although the case where cesium 5 was used as an impurity which becomes a positive fixed charge was described, it is not limited to this, for example, lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, One containing at least one selected from the group consisting of barium, phosphorus, arsenic and antimony can be used.

  In the photoelectric conversion device of this embodiment having the above structure, the p-type and n-type conductivity types may be interchanged. In this case, an impurity that becomes a negative fixed charge can be used instead of an impurity that becomes a positive fixed charge such as cesium. Examples of the impurity that becomes a negative fixed charge include those containing at least one selected from the group consisting of boron, aluminum, gallium, indium, platinum, fullerene fluoride, fullerene oxide, fluorine, chlorine, bromine, and iodine. Can be used.

  Note that the impurity that becomes a positive fixed charge and the impurity that becomes a negative fixed charge may each be included in an oxide state.

  Further, in the photoelectric conversion device of the present embodiment having the above-described configuration, the locations where the above-mentioned impurities are most present are the first amorphous silicon layer 2a as the first semiconductor layer and the silicon oxide film as the surface dielectric film. 6 from the interface to the first amorphous silicon layer 2a as the first semiconductor layer in the direction perpendicular to the interface, and to the silicon oxide film 6 side as the surface dielectric film It is preferably located in a region between the region advanced by 5 nm. In this case, the characteristics of the photoelectric conversion device of the present embodiment having the above configuration tend to be further improved.

  That is, in the photoelectric conversion device of the present invention, the surface dielectric film may have an impurity that becomes a positive or negative fixed charge in the vicinity of the interface with the first semiconductor layer. A part of the region advances from the interface between the first semiconductor layer and the surface dielectric film by 5 nm toward the first semiconductor layer in a direction perpendicular to the interface and 5 nm toward the surface dielectric film. It suffices if it exists in a region between the facing regions.

  In the above, the silicon oxide film 6 on the light incident side of the first amorphous silicon layer 2a may function as an antireflection film, and a texture structure and / or a moth-eye structure is formed on the surface of the silicon oxide film 6. Needless to say.

  In the photoelectric conversion device of this embodiment having the above-described structure, a case where a stacked structure in which three layers of the first semiconductor layer, the second semiconductor layer, and the third semiconductor layer are stacked has been described. Needless to say, it is not limited to layers.

  Further, as described above, in the photoelectric conversion device of the present embodiment having the above-described configuration, the n-type and p-type conductivity types may be interchanged. Note that when the n-type and p-type conductivity types are interchanged in the photoelectric conversion device of the present embodiment having the above-described configuration, the polarities of the positive and negative charges are also interchanged.

  In the case where amorphous silicon is used for each of the first semiconductor layer, the second semiconductor layer, and the third semiconductor layer as in the photoelectric conversion device of this embodiment, the first semiconductor layer, the second semiconductor layer, Each of the semiconductor layer and the third semiconductor layer preferably has a p + layer on the light incident side surface. This is due to the following reason. Carrier generation during light irradiation occurs frequently on the light incident side of the semiconductor layer. Therefore, by providing a p + layer on the surface of the semiconductor layer on the light incident side, holes having a lifetime shorter than that of electrons are increased to p +. The moving distance until reaching the layer can be reduced. Therefore, conversion efficiency can be improved by suppressing recombination of holes.

  In the photoelectric conversion device of the present embodiment configured as described above, as the transparent conductive film 9, for example, a single-layer or a multi-layer stack of layers made of ITO, IO, TO, or ZO can be used.

  In the photoelectric conversion device of the present embodiment having the above configuration, a metal electrode may be used instead of the transparent conductive film 9. However, when a metal electrode is used as an electrode in contact with the first semiconductor layer, it is preferable that the electrode be formed only on a part of the surface of the first semiconductor layer in consideration of light incidence.

<Embodiment 6>
FIG. 6 shows a schematic cross-sectional view of another example of the photoelectric conversion device of the present invention. Here, in the photoelectric conversion device of the present embodiment having the configuration shown in FIG. 6, one surface of the first amorphous silicon layer 2 a as the first semiconductor layer of the first photoelectric conversion layer 51 on the light incident side surface. The n + layer 3 is formed in the part, and the transparent conductive film 9 is formed in contact with the n + layer 3.

  By adopting the configuration as in this embodiment, the contact resistance of the transparent conductive film 9 can be reduced as compared with the photoelectric conversion device in the configuration of Embodiment 5, so that the photoelectric conversion efficiency of the photoelectric conversion device, etc. It becomes possible to improve the characteristics.

  Further, in the silicon oxide film 6 of the photoelectric conversion device of the present embodiment, ionized cesium 5 serving as a positive fixed charge is disposed in the vicinity of the interface with the light incident side surface of the first amorphous silicon layer 2a. Therefore, negative charges are induced in the region of the n + layer 3 in contact with the silicon oxide film 6 to form the accumulation layer 13. Contact resistance between the storage layer 13 and the transparent conductive film 9 can also reduce the contact resistance of the transparent conductive film 9. Note that, in the configuration of the photoelectric conversion device according to any of the embodiments described above and below, the overlapping region of the inversion layer in which the negative charge is induced and the n + layer, and the inversion layer in which the positive charge is induced and the p It goes without saying that any overlapping area with the + layer can be a storage layer.

The n + layer 3 is provided with a mask having an opening at a location corresponding to the location where the n + layer 3 is formed on the light incident side surface of the first amorphous silicon layer 2a as the first semiconductor layer. Later, n-type impurities can be formed by diffusing from this opening. The n-type impurity can be diffused by vapor phase diffusion using a gas containing an n-type impurity such as POCl ₃ . Further, for example, the n + layer 3 can be formed by doping an n-type impurity such as phosphorus, arsenic or antimony by ion implantation or ion doping into the opening.

  Since the description other than the above in the present embodiment is the same as that of the fifth embodiment, the description thereof is omitted here.

<Embodiment 7>
FIG. 7 shows a schematic cross-sectional view of another example of the photoelectric conversion device of the present invention. Here, in the photoelectric conversion device of the present embodiment having the configuration shown in FIG. 7, one surface of the first amorphous silicon layer 2 a as the first semiconductor layer of the first photoelectric conversion layer 51 on the light incident side. This is characterized in that the metal silicide 10 is formed on the part.

  By adopting the configuration as in the present embodiment, the metal silicide 10 has a low resistance like metal, so that a low resistance comb-shaped electrode can be formed by the metal silicide 10, and the transparent conductive film As a result, it is possible to improve characteristics such as the photoelectric conversion efficiency of the photoelectric conversion device as compared with the photoelectric conversion device of Embodiment 5.

  The metal silicide 10 can be formed, for example, by using a conventionally known self-aligned silicidation (SALICIDE) process. By using the SALICIDE process, an electrode processing mask is not required, and an electrode can be easily formed.

The metal silicide 10 can be used without particular limitation as long as it is made of a compound of at least one arbitrary metal and silicon. Examples of metals that combine with silicon include Ti, Ni, Co, Er, Yb, Pt, etc. are mentioned. Among these, as the metal compound with silicon, low temperature formable nickel silicide _{(Ni x Si (x ≒ 0.5~2} )) or cobalt silicide _{(Co x Si (x ≒ 0.5~2} )) , etc. Can be used.

  In the photoelectric conversion device of this embodiment, the wiring layer may be formed using a transparent conductive film or the like in contact with the metal silicide 10.

  Since the description other than the above in the present embodiment is the same as that of the fifth embodiment, the description thereof is omitted here.

<Eighth embodiment>
FIG. 8 shows a schematic cross-sectional view of another example of the photoelectric conversion device of the present invention. Here, in the photoelectric conversion device of the present embodiment having the configuration shown in FIG. 8, one surface of the first amorphous silicon layer 2 a as the first semiconductor layer of the first photoelectric conversion layer 51 on the light incident side surface. A metal silicide 10 is formed on the portion, and an n + layer 3 formed by segregation of n-type impurities in a region between the metal silicide 10 and the first amorphous silicon layer 2a is formed. There are features.

  Also in the configuration of the present embodiment, the rectification characteristics between the metal silicide 10 and the first amorphous silicon layer 2a can be improved compared to the photoelectric conversion device of the configuration of the seventh embodiment, and Since the resistance between the metal silicide 10 and the surface inversion layer 4 can be lowered, characteristics such as photoelectric conversion efficiency of the photoelectric conversion device can be improved.

  Further, by adopting the configuration as in this embodiment, the contact resistance of the transparent conductive film 9 can be further reduced as compared with the photoelectric conversion device having the configuration in Embodiment 7, and thus the photoelectric conversion device of the photoelectric conversion device can be reduced. It is possible to further improve characteristics such as conversion efficiency.

  In the photoelectric conversion device of this embodiment, a transparent conductive film in contact with the metal silicide 10 may be formed.

  Since the description other than the above in the present embodiment is the same as that in the fifth to seventh embodiments, the description thereof is omitted here.

<Embodiment 9>
FIG. 9 shows a schematic cross-sectional view of another example of the photoelectric conversion device of the present invention. Here, in the photoelectric conversion device of the present embodiment configured as shown in FIG. 9, the surface dielectric film 4 has a positive polarity so as to be in contact with the back surface of the third amorphous silicon layer 2c of the third photoelectric conversion layer 53. This is characterized in that a silicon oxide film 60 is formed as a back surface dielectric film having an impurity 50 which is a negative fixed charge having a polarity opposite to that of cesium 5 which is a fixed charge.

  Here, the negative fixed charge contained in the back surface dielectric film becomes negative fixed charge by ionization or the like in the vicinity of the interface with the back surface of the third amorphous silicon layer 2c. A back surface inversion layer 40 that functions as a p-type semiconductor is induced in at least a partial region of the back surface of the third amorphous silicon layer 2c in contact with the film.

  In the photoelectric conversion device of the present embodiment configured as described above, a transparent electrode such as a transparent conductive film is used as the back electrode 7, and not only from the first photoelectric conversion layer 51 side but also from the third photoelectric conversion layer 53 side. In addition, when light is incident, absorption of short-wavelength light by the p + layer 1 of the third photoelectric conversion layer can be suppressed, so that characteristics such as photoelectric conversion efficiency of the photoelectric conversion device can be improved. It becomes possible.

  Although the silicon oxide film 60 is used as the back surface dielectric film, it is needless to say that it is not limited to this. For example, at least one selected from the group consisting of silicon oxide, silicon oxynitride, and silicon nitride is used. May be.

  Further, in the photoelectric conversion device of the present embodiment having the above-described configuration, the portion where the impurity 50 contained most in the silicon oxide film 60 as the back surface dielectric film is present is the third amorphous silicon as the third semiconductor layer. A region advanced from the interface between the layer 2c and the silicon oxide film 60 as the back dielectric film by 5 nm toward the third amorphous silicon layer 2c as the third semiconductor layer in a direction perpendicular to the interface; It is preferably located in a region between the region advanced 5 nm toward the silicon oxide film 60 side as the back surface dielectric film. In this case, the characteristics of the photoelectric conversion device of the present embodiment having the above configuration tend to be further improved.

  In other words, in the photoelectric conversion device of the present invention, the back surface dielectric film is fixed in the vicinity of the interface with the third semiconductor layer and has a polarity opposite to that of the impurities that are positive or negative fixed charges contained in the surface dielectric film. It is preferable to have an impurity serving as a charge, but at least a part of this impurity is from the interface between the third semiconductor layer and the back surface dielectric film in the direction perpendicular to the interface. It suffices to exist in a region between the region advanced 5 nm toward the layer side and the region advanced 5 nm toward the back surface dielectric film side.

  Since the description other than the above in the present embodiment is the same as that of the fifth embodiment, the description thereof is omitted here.

<Embodiment 10>
FIG. 10 shows a schematic perspective view of another example of the photoelectric conversion device of the present invention. Here, irregularities 15 are formed on the light incident surface of the p-type silicon substrate 2 as the semiconductor layer of the photoelectric conversion device of the present embodiment having the configuration shown in FIG. 10, and the irregularities 15 are formed. On the surface of the p-type silicon substrate 2 on the light incident side, a silicon oxide film 6 as a surface dielectric film is provided. An n + layer 3 is formed on a part of the light incident side surface of the p-type silicon substrate 2 as a semiconductor layer.

  The silicon oxide film 6 has cesium (not shown) as an impurity that becomes a positive fixed charge in the vicinity of the interface with the light incident side surface of the p-type silicon substrate 2, and the cesium is p-type. Since it is ionized near the interface with the light incident side surface of the silicon substrate 2 and becomes a positive fixed charge, at least a partial region of the light incident side surface of the p-type silicon substrate 2 in contact with the silicon oxide film 6 As in the case of the n + layer 3, a surface inversion layer 4 that functions as an n-type semiconductor is induced.

  A p + layer 1 is formed on a part of the back surface opposite to the light incident surface of the p-type silicon substrate 2, and silicon oxide is formed on the back surface of the p-type silicon substrate 2. A membrane 26 is installed. A back electrode 7 is formed on the back surface of the p-type silicon substrate 2 via a silicon oxide film 26. The back electrode 7 is formed on the back surface of the p + layer 1 through an opening formed in the silicon oxide film 26. It is formed so as to contact a part.

  A metal electrode 8 as a surface electrode is formed on the light incident side surface of the p-type silicon substrate 2 via a silicon oxide film 6, and the metal electrode 8 is an opening formed in the silicon oxide film 6. And is in contact with part of the surface of the n + layer 3.

  Hereinafter, an example of a method for manufacturing the photoelectric conversion device of the present embodiment having the configuration shown in FIG. 10 will be described. First, the irregularities 15 are formed on the light incident surface of the p-type silicon substrate 2. Here, the irregularities 15 can be formed, for example, by forming a texture structure on the light incident side surface of the p-type silicon substrate 2 by wet etching using a potassium hydroxide aqueous solution or a sodium hydroxide aqueous solution.

  Further, the unevenness 15 can be formed by removing a part of the light incident side surface of the p-type silicon substrate 2 by, for example, laser light irradiation, RIE (Reactive Ion Etching) or plasma irradiation. .

  Next, a silicon oxide film 6 is formed on the light incident side surface of the p-type silicon substrate 2 and a silicon oxide film 26 is formed on the back surface of the p-type silicon substrate 2 opposite to the light incident side surface. To do. Here, when the p-type silicon substrate 2 is made of single crystal silicon, the silicon oxide film 6 is formed on the surface of the p-type silicon substrate 2 on the light incident side by, for example, thermal oxidation at a temperature of 950 ° C. or higher. A silicon oxide film 26 can be formed on the back surface of the p-type silicon substrate 2.

Next, the p + layer 1 is formed on the back surface of the p-type silicon substrate 2. Here, the formation of the p + layer 1 is performed by, for example, placing a mask having an opening at a position corresponding to the position where the p + layer 1 is formed on the back surface of the p type silicon substrate 2 and then p-type impurities from the opening. This can be done by diffusing. The p-type impurity can be diffused by vapor phase diffusion using a gas containing a p-type impurity such as BBr ₃ .

Next, the n + layer 3 is formed on the light incident side surface of the p-type silicon substrate 2. Here, the formation of the n + layer 3 can be performed by diffusing n-type impurities on the surface of the p-type silicon substrate 2 on the light incident side. The diffusion of the n-type impurity is, for example, by providing an opening in a part of the silicon oxide film 6 at a location corresponding to the location where the n + layer 3 is formed, and a gas containing an n-type impurity such as POCl ₃ from the opening. Can be carried out by vapor phase diffusion using.

  Next, cesium 5 is contained in the silicon oxide film 6 formed on the light incident side surface of the p-type silicon substrate 2. Here, the cesium 5 contains, for example, cesium 5 ionized into the silicon oxide film 6 by ion-implanting cesium ions into the silicon oxide film 6 formed on the light incident side surface of the p-type silicon substrate 2. Can be made.

  Next, the p-type silicon substrate 2 is annealed. Here, annealing of the p-type silicon substrate 2 can be performed, for example, by annealing the p-type silicon substrate 2 after the cesium ion implantation at a temperature of, for example, 800 ° C. to 1000 ° C. As a result, ionized cesium 5 in the silicon oxide film 6 can be segregated at the interface with the surface of the p-type silicon substrate 2 on the light incident side, so that the light incident on the p-type silicon substrate 2 in contact with the silicon oxide film 6 The surface inversion layer 4 is formed on the surface on the side.

  Next, the metal electrode 8 is formed on the light incident side surface of the p-type silicon substrate 2. Here, for example, the metal electrode 8 is provided with an opening in the silicon oxide film 6 at a position where the surface of the n + layer 3 to be in contact with the metal electrode 8 is exposed, and the metal is deposited in a predetermined shape using a mask or the like. Or the like.

  Next, the back electrode 7 is formed on the back surface of the p-type silicon substrate 2. Here, the back electrode 7 is formed, for example, by providing an opening in the silicon oxide film 6 at a location where the surface of the p + layer 1 to be in contact with the back electrode 7 is exposed, and evaporating metal using a mask or the like. can do.

  Finally, by annealing the p-type silicon substrate 2 after the formation of the metal electrode 8 and the back electrode 7, an example of the photoelectric conversion device of the present embodiment having the above-described configuration is manufactured. Here, annealing of the p-type silicon substrate 2 can be performed by exposing the p-type silicon substrate 2 to a hydrogen atmosphere at a temperature of 350 ° C. to 500 ° C., for example.

  In the photoelectric conversion device of the present embodiment having the above-described configuration manufactured as described above, the silicon oxide film 6 and the surface on the light incident side of the p-type silicon substrate 2 are in contact with each other, and the p-type of the silicon oxide film 6 is formed. The surface inversion layer 4 is formed on the light incident side surface of the p-type silicon substrate 2 by cesium ionized at the interface with the light incident side surface of the silicon substrate 2.

  Therefore, in the photoelectric conversion device according to the present embodiment having the above-described configuration, it is described in Patent Document 1 in which a first layer that does not include a fixed charge is provided between a second layer that includes a fixed charge and a semiconductor surface. Compared to the solar cell, negative charges are more easily induced in the surface inversion layer 4 at a high density, the function as an n-type semiconductor is enhanced, and the recombination of carriers on the light incident side surface of the p-type silicon substrate 2 is suppressed. This improves the characteristics of the photoelectric conversion device such as the photoelectric conversion efficiency.

  Further, by providing the surface inversion layer 4 functioning as an n-type semiconductor instead of the n + layer 3 serving as an absorption source of short-wavelength light on the light incident side surface of the p-type silicon substrate 2, short-wavelength light is provided. Therefore, the characteristics of the photoelectric conversion device such as the photoelectric conversion efficiency can be further improved.

  In addition, by disposing a fixed charge in the silicon oxide film 6, the built-in potential is increased as compared with the case where the n + layer 3 is formed, so that the internal electric field of the p-type silicon substrate 2 is increased. Due to this large internal electric field, the drift component is more dominant in the carrier conduction than the diffusion component, the carrier moving speed is increased, and the recombination of carriers is suppressed. Thereby, carrier collection efficiency can be improved.

  Further, in the photoelectric conversion device of the present embodiment having the above-described configuration, the negative polarity induced in the surface inversion layer 4 by the segregation amount of cesium at the interface between the silicon oxide film 6 and the light incident side surface of the p-type silicon substrate 2. The charge density can be controlled.

  In particular, when cesium is segregated at the interface between the silicon oxide film 6 and the p-type silicon substrate 2 by cesium ion implantation into the silicon oxide film 6 and annealing as in the present embodiment, an optimum negative in the surface inversion layer 4 is obtained. Since the margin of the cesium ion implantation amount for obtaining the charge density is wide, a photoelectric conversion device with stable quality and high characteristics can be provided.

  In the photoelectric conversion device of the present embodiment configured as described above, the interface state on the light incident side surface of the p-type silicon substrate 2 is terminated with a negative charge induced in the surface inversion layer 4, thereby forming the p-type. Recombination of carriers at the interface state on the light incident surface of the silicon substrate 2 is suppressed, and characteristics of the photoelectric conversion device such as photoelectric conversion efficiency can be further improved.

  Furthermore, in the photoelectric conversion device according to the present embodiment having the above-described configuration, the unevenness 15 formed on the light incident side surface of the p-type silicon substrate 2 and the surface opposite to the light incident side surface of the p-type silicon substrate 2. The light confinement effect inside the p-type silicon substrate 2 can also be obtained by the back electrode 7 formed on the back surface of the p-type silicon substrate 2.

  Since the description other than the above in the present embodiment is the same as that in the first embodiment, the description thereof is omitted here.

<Embodiment 11>
FIG. 11 shows a schematic perspective view of another example of the photoelectric conversion device of the present invention. Here, in the photoelectric conversion device of the present embodiment having the configuration shown in FIG. 11, a silicon oxide film 60 as a back dielectric film is disposed on the back surface of the p-type silicon substrate 2. In the vicinity of the interface with the back surface of the p-type silicon substrate 2, a negative fixed charge having a polarity different from that of cesium contained in the silicon oxide film 6 provided as a surface dielectric film on the light incident side surface of the p-type silicon substrate 2 is obtained. It is characterized by having impurities (not shown).

Here, the silicon oxide film 60 has an impurity that becomes a negative fixed charge in the vicinity of the interface with the back surface of the p-type silicon substrate 2, and the impurity that becomes a negative fixed charge is the back surface of the p-type silicon substrate 2. As in the case of the p + layer 1, the p-type semiconductor is formed in at least a part of the back surface of the p-type silicon substrate 2 in contact with the silicon oxide film 60. As a result, the back surface accumulation layer 40 is induced.

In the photoelectric conversion device of the present embodiment configured as described above, not only the surface inversion layer 4 is formed on the surface of the p-type silicon substrate 2 on the light incident side, but also the surface of the p-type silicon substrate 2 on the light incident side. The back surface accumulation layer 40 is formed on the back surface on the opposite side to the surface, and the recombination of carriers can be suppressed on the light incident side surface of the p-type silicon substrate 2 and the back surface on the opposite side. Compared with ten photoelectric conversion devices, characteristics of the photoelectric conversion device such as photoelectric conversion efficiency can be further improved. Further, in the photoelectric conversion device of the present embodiment having the above configuration, light absorption by the p + layer 1 can be suppressed as compared with the photoelectric conversion device of the tenth embodiment.

  Although the silicon oxide film 60 is used as the back surface dielectric film, it is needless to say that it is not limited to this. For example, at least one selected from the group consisting of silicon oxide, silicon oxynitride, and silicon nitride is used. May be.

  Further, a method similar to that for the silicon oxide film 6 as the surface dielectric film can be used as a method for causing the silicon oxide film 60 as the back surface dielectric film to contain an impurity that becomes a negative fixed charge.

  Further, in the photoelectric conversion device of the present embodiment having the above-described configuration, the locations where the most impurities contained in the silicon oxide film 60 as the back surface dielectric film are present are the p-type silicon substrate 2 as the semiconductor layer and the back surface dielectric. From the interface with the silicon oxide film 60 as the film, the region advanced 5 nm toward the p-type silicon substrate 2 in the direction perpendicular to the interface, and 5 nm toward the silicon oxide film 60 side as the back dielectric film. It is preferable to be located in a region between the two regions. In this case, the characteristics of the photoelectric conversion device of the present embodiment having the above configuration tend to be further improved.

  That is, in the photoelectric conversion device of the present invention, the back surface dielectric film has a fixed charge with a polarity opposite to the positive or negative fixed charge contained in the surface dielectric film in the vicinity of the interface with the semiconductor layer. Although it is preferable to have an impurity, a region in which at least a part of the impurity advances from the interface between the semiconductor layer and the back surface dielectric film by 5 nm toward the semiconductor layer in a direction perpendicular to the interface; It suffices to be present in a region between the region advanced 5 nm toward the back surface dielectric film side.

  Since the description other than the above in the present embodiment is the same as that in the first and tenth embodiments, the description thereof is omitted here.

<Embodiment 12>
FIG. 12 is a schematic cross-sectional view of another example of the photoelectric conversion device of the present invention. The photoelectric conversion device of the present embodiment having the configuration shown in FIG. 12 includes a thin film silicon layer 12a as a first semiconductor layer and a first dielectric film bonded to the light incident surface of the thin film silicon layer 12a. The silicon oxide film 6a, the silicon oxide film 6b as the second dielectric film bonded to the back surface opposite to the light incident surface of the thin film silicon layer 12a, and the back surface of the silicon oxide film 6b In addition, it has a configuration including a laminated structure with a thin film silicon layer 12b as a second semiconductor layer. Further, it may have a periodic structure of (silicon oxide film containing positive fixed charges) / (thin film silicon layer) / (silicon oxide film containing negative fixed charges).

  Further, the silicon oxide film 6a has an impurity 20 that becomes a positive fixed charge in the vicinity of the interface with the thin film silicon layer 12a. Here, in the silicon oxide film 6a, since the impurity 20 which becomes a positive fixed charge becomes a positive fixed charge by ionization or the like, the surface of the light incident side of the thin film silicon layer 12a with which the silicon oxide film 6a is in contact is formed. Negative charge is induced in at least a part of the region to induce the first inversion layer 4a functioning as an n-type semiconductor.

  Further, the silicon oxide film 6b has an impurity 21 that becomes a negative fixed charge in the vicinity of the interface with the thin film silicon layer 12a and in the vicinity of the interface with the thin film silicon layer 12b. Here, in the silicon oxide film 6b, the impurity 21 that becomes a negative fixed charge becomes a negative fixed charge by ionization or the like. Therefore, at least a part of the back surface of the thin film silicon layer 12a with which the silicon oxide film 6b is in contact. A positive charge is induced in the region to induce the second inversion layer 4b functioning as a p-type semiconductor, and at least a part of the light incident side surface of the thin film silicon layer 12b in contact with the silicon oxide film 6b is formed in the region. Positive charge is induced to induce a third inversion layer 4c that functions as a p-type semiconductor.

  Further, another laminated structure having the above-described configuration is bonded to the back surface of the thin film silicon layer 12b. The outermost layer of the bonded stacked structure has a positive fixed charge in the vicinity of the interface with the back surface of the thin film silicon layer 12b. The silicon oxide film 6c including the impurity 20 is disposed, and the impurity 20 has a positive fixed charge in the silicon oxide film 6c. Thereby, a negative charge is induced on the back surface of the thin film silicon layer 12b to induce the fourth inversion layer 4d functioning as an n-type semiconductor.

  Therefore, in the photoelectric conversion device of the present embodiment having the above-described configuration, a photoelectric conversion layer having a pin structure is formed by each semiconductor layer and the inversion layers formed on both surfaces of each semiconductor layer. The layers are sequentially stacked.

  Note that, in the above, positive fixed charges or negative fixed charges may be present at least in the vicinity of the interface, and therefore may be present in the silicon oxide film.

  Further, an n-type semiconductor layer 17 as a first conductivity type semiconductor layer is provided on one side surface of the stacked structure having the above configuration, and a second conductivity type semiconductor layer is provided on the other side surface of the stacked structure having the above configuration. The p-type semiconductor layer 16 is provided, and the n-type semiconductor layer 17 and the p-type semiconductor layer 16 are provided with electrodes (not shown).

  When light is incident on the photoelectric conversion device of the present embodiment having the above structure, electrons move out of the carriers generated in the thin film silicon layer 12a toward the silicon oxide film 6a having the impurity 20 that becomes a positive fixed charge. Then, the silicon oxide film 6 a and the n-type semiconductor layer 17 are taken out from the electrode provided on the n-type semiconductor layer 17. On the other hand, of the carriers generated in the thin film silicon layer 12a, holes move to the silicon oxide film 6b side having the impurities 21 that become negative fixed charges, pass through the silicon oxide film 6b and the p-type semiconductor layer 16, and p It is taken out from the electrode placed on the mold semiconductor layer 16.

  Similarly, when light is incident on the photoelectric conversion device of the present embodiment having the above-described configuration, among the carriers generated in the thin film silicon layer 12b, electrons are on the side of the silicon oxide film 6c having the impurity 20 that becomes a positive fixed charge. , Passes through the silicon oxide film 6 c and the n-type semiconductor layer 17, and is taken out from the electrode provided on the n-type semiconductor layer 17. On the other hand, of the carriers generated in the thin film silicon layer 12b, holes move to the silicon oxide film 6b side having the impurities 21 that become negative fixed charges, pass through the silicon oxide film 6b and the p-type semiconductor layer 16, and p. It is taken out from the electrode placed on the mold semiconductor layer 16.

  Carrier extraction by the mechanism as described above is performed on each semiconductor layer and each dielectric film of the stacked structure that constitutes the photoelectric conversion device of this embodiment, so that carriers are extracted from the photoelectric conversion device of this embodiment. Can be taken out.

  Hereinafter, an example of a method for manufacturing the photoelectric conversion device of the present embodiment having the configuration shown in FIG. 12 will be described. First, a laminated structure in which the above laminated structure is repeated three periods is formed on the surface of the substrate.

  Here, the laminated structure is formed by using, for example, a CVD method on a surface of a predetermined substrate such as a glass substrate, a silicon oxide film containing an impurity that becomes a negative fixed charge, a thin film silicon layer, a positive fixed charge. Then, the silicon oxide film and the thin film silicon layer containing the impurities to be formed can be sequentially stacked in this order.

  As a method for introducing an impurity that becomes a positive fixed charge or an impurity that becomes a negative fixed charge into the silicon oxide film, for example, an impurity that becomes a positive fixed charge after a thin film silicon layer is formed by a CVD method or the like. Or ions of impurities that become negative fixed charges may be implanted. Moreover, after applying and drying an aqueous solution containing an impurity that becomes a positive or negative fixed charge, such as a cesium hydroxide aqueous solution, a cesium chloride aqueous solution, or an aluminum hydroxide aqueous solution, the silicon oxide film is formed by a CVD method. By forming the silicon oxide film, a silicon oxide film containing an impurity that becomes a positive or negative fixed charge such as cesium or aluminum can be formed. Alternatively, it can be formed by bonding a thin film silicon layer formed on the surface with a silicon oxide film containing an impurity that becomes a positive fixed charge by ion implantation or the like. For example, after a silicon oxide film is formed on the surface of a single crystal silicon substrate by thermal oxidation or the like, impurities that become fixed charges are introduced into the silicon oxide film by ion implantation or the like and annealed. Next, by using a smart cut method or the like, the surface of the single crystal silicon substrate can be peeled and sequentially stacked on a glass substrate or the like.

  Next, a part of the laminated structure is removed to expose a part of the surface of the substrate. Here, the removal of the laminated structure can be performed by etching, for example.

  Next, as shown in the schematic cross-sectional view of FIG. 13, for example, an n-type semiconductor layer 17 and a p-type semiconductor layer 16 are deposited on the removed portion of the stacked structure. Here, the n-type semiconductor layer 17 and the p-type semiconductor layer 16 can be deposited by, for example, a CVD method.

  Thereafter, for example, as shown in FIG. 13, an n-type electrode 18 is formed on the surface of the n-type semiconductor layer 17, and a p-type electrode 19 is formed on the surface of the p-type semiconductor layer 16. Here, each of the n-type electrode 18 and the p-type electrode 19 can be formed, for example, by vapor-depositing a metal used for the n-type electrode 18 and a metal used for the p-type electrode 19. .

  Finally, for example, the n-type semiconductor layer 17 and the p-type semiconductor layer 16 are cut along the broken lines shown in FIG. 13, whereby the photoelectric conversion device of the present embodiment having the configuration shown in FIG. 12 can be manufactured. . Further, wiring may be appropriately formed without cutting the n-type semiconductor layer 17 and the p-type semiconductor layer 16.

  In the photoelectric conversion device of the present embodiment having the above structure manufactured as described above, the silicon oxide film 6a is in contact with the thin film silicon layer 12a, and the silicon oxide film 6b is formed of the thin film silicon layer 12a and the thin film silicon layer 12b. Is in contact with both.

  Therefore, in the photoelectric conversion device according to the present embodiment having the above-described configuration, it is described in Patent Document 1 in which a first layer that does not include a fixed charge is provided between a second layer that includes a fixed charge and a semiconductor surface. Compared with the solar cell, positive or negative charges are more easily induced in the inversion layers such as the first inversion layer 4a, the second inversion layer 4b, the third inversion layer 4c, and the fourth inversion layer 4d. Thus, since the function as an n-type semiconductor or a p-type semiconductor is enhanced, the recombination of carriers on the surface of each semiconductor layer is suppressed, and thus the characteristics of the photoelectric conversion device such as photoelectric conversion efficiency are improved.

  In the photoelectric conversion device of the present embodiment having the above-described configuration, the n + layer or p serving as an absorption source of short-wavelength light on the surface of the semiconductor layer such as the thin film silicon layer 12a and the thin film silicon layer 12b on the light incident side. By providing an inversion layer functioning as an n-type semiconductor or a p-type semiconductor instead of the + layer, absorption of light having a short wavelength can be suppressed as compared with the n + layer or the p + layer. The characteristics of the conversion device can be further improved.

  Further, in the photoelectric conversion device of this embodiment having the above-described configuration, the inversion is performed depending on the amount of segregation of impurities that become positive or negative fixed charges at the interface between the dielectric film such as a silicon oxide film and the semiconductor layer such as a thin film silicon layer. The density of positive or negative charges induced in the layer can be controlled.

  Further, in the photoelectric conversion device of the present embodiment having the above-described configuration, the interface state on the light incident side surface of the thin film silicon layer 12a is terminated with a negative charge induced in the first inversion layer 4a, whereby the thin film Carrier recombination at the interface state on the light incident side surface of the silicon layer 12a is suppressed, and characteristics of the photoelectric conversion device such as photoelectric conversion efficiency can be further improved.

  In the above, thin film silicon layers are used for the first semiconductor layer and the second semiconductor layer, respectively, but the thin film silicon layer is made of, for example, crystalline silicon, amorphous silicon, or microcrystalline silicon. Alternatively, it may be made of a semiconductor other than silicon. Note that crystalline silicon includes single crystal silicon, polycrystalline silicon, a mixture of single crystal silicon and polycrystalline silicon, or the like.

  In addition, the material may be different for each semiconductor layer of the stacked structure. For example, the structure may include amorphous silicon, polycrystalline silicon, and single crystal silicon in this order from the light incident side.

  Further, when crystalline silicon is used for each semiconductor layer, the above laminated structure can be produced by, for example, bonding together crystalline silicon on which the dielectric film is formed.

  In the photoelectric conversion device of this embodiment having the above structure, the band gap of the semiconductor layer close to the light incident side is preferably equal to or larger than the band gap of the semiconductor layer farther from the light incident side than the semiconductor layer. By adopting a stacked structure of semiconductor layers that can sequentially absorb short-wavelength light from long-wavelength light from the light incident side, the amount of light incident on the photoelectric conversion device of this embodiment is increased. Therefore, characteristics of the photoelectric conversion device of this embodiment such as photoelectric conversion efficiency tend to be improved.

  As a laminated structure of the semiconductor layer having such a band gap relationship, for example, a structure in which amorphous silicon carbide, amorphous silicon and microcrystalline silicon are laminated from the light incident side, and an amorphous structure from the light incident side. A structure in which silicon carbide, amorphous silicon, and amorphous silicon germanium are stacked can be given.

  The thickness of at least one semiconductor layer constituting the stacked structure is preferably thinner than the carrier diffusion length in the semiconductor layer. In this case, recombination of carriers in the semiconductor layer can be effectively suppressed and the probability that incident light is absorbed can be increased by using a stacked structure as in this embodiment. it can.

  In the above, the silicon oxide film is used as the dielectric film constituting the laminated structure such as the first dielectric film and the second dielectric film, but it is needless to say that the present invention is not limited thereto. At least one selected from the group consisting of silicon oxide, silicon oxynitride, and silicon nitride can also be used.

  In addition, as the dielectric film constituting the laminated structure such as the first dielectric film and the second dielectric film, it is preferable to use a dielectric film having a band gap of 4.2 eV or more. For example, since most of sunlight is composed of light having a wavelength of 300 nm or more, when sunlight is incident using a dielectric film having a band gap of 4.2 eV or more, a wavelength of 300 nm or more is used. Since the solar light having a thickness is suppressed from being absorbed by the dielectric film and the conversion loss is reduced, the characteristics of the photoelectric conversion device tend to be further improved.

  In the above, the positive fixed charge is, for example, at least one selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, barium, phosphorus, arsenic, and antimony. Those containing seeds can be used.

  Examples of the impurity that becomes a negative fixed charge include those containing at least one selected from the group consisting of boron, aluminum, gallium, indium, platinum, fullerene fluoride, fullerene oxide, fluorine, chlorine, bromine, and iodine. Can be used.

  In the photoelectric conversion device of this embodiment having the above-described configuration, the p-type and n-type conductivity types may be switched, and the polarity of the fixed charge may be switched.

  Further, in the photoelectric conversion device of the present embodiment having the above-described configuration, the portion where the above-described impurity is most present is from the interface between the semiconductor layer and the dielectric film toward the semiconductor layer in a direction perpendicular to the interface. It is preferably located in a region between the region advanced by 5 nm and the region advanced by 5 nm toward the dielectric film side. In this case, the characteristics of the photoelectric conversion device of the present embodiment having the above configuration tend to be further improved.

  That is, at least a part of the impurities that become positive or negative fixed charges in each dielectric film advances from the interface between the semiconductor layer and the dielectric film to the semiconductor layer side in a direction perpendicular to the interface by 5 nm. It suffices to exist in a region between the region and the region advanced by 5 nm toward the dielectric film side.

  In the photoelectric conversion device of the present embodiment having the above-described configuration, the silicon oxide film 6a on the light incident side of the thin film silicon layer 12a may function as an antireflection film, and the texture structure and the surface of the silicon oxide film 6a Needless to say, a moth-eye structure or the like may be formed.

  Needless to say, the number of semiconductor layers and the number of dielectric films in the photoelectric conversion device of the present embodiment having the above-described configuration are not limited to the above-described configuration.

  Further, as described above, in the photoelectric conversion device of the present embodiment having the above-described configuration, the n-type and p-type conductivity types may be interchanged. Note that when the n-type and p-type conductivity types are interchanged in the photoelectric conversion device of the present embodiment having the above-described configuration, the polarities of the positive and negative charges are also interchanged.

  FIG. 14 is a schematic cross-sectional view of a sample of the photoelectric conversion device manufactured in this example. Here, in the sample of the photoelectric conversion device shown in FIG. 14, the n + layer 102 is formed on a part of the light incident side surface of the p-type silicon substrate 101. Further, a silicon oxide film 105 and a silicon nitride film 106 are formed in this order on the light incident side surface of the p-type silicon substrate 101, and contact holes provided in the silicon oxide film 105 and the silicon nitride film 106 are formed. An electrode 107 in contact with the n + layer 102 is provided. Furthermore, since the silicon oxide film 105 has ionized cesium 104 in the vicinity of the interface with the surface on the light incident side of the p-type silicon substrate 101, the light incident side of the p-type silicon substrate 101 with which the silicon oxide film 105 is in contact. A surface inversion layer 103 functioning as an n-type semiconductor is formed by inducing negative charges in the surface region. Although not shown, a back electrode is formed on the back surface of the p-type silicon substrate 101.

  Hereinafter, a method for manufacturing a sample of the photoelectric conversion device having the structure illustrated in FIG. 14 will be described with reference to a flowchart illustrated in FIG.

  First, in step S1, p-type silicon substrate 101 is fabricated by annealing silicon into which boron ions have been implanted at a temperature of 1190 ° C.

  Next, in step S2, a silicon oxide film 105 is formed on the light incident side surface of the p-type silicon substrate 101 by a thermal oxidation method, and then a silicon nitride film 106 is formed by a plasma CVD method.

Next, in step S3, after providing a contact hole in a part of the stacked body of the silicon oxide film 105 and the silicon nitride film 106, the n + layer 102 is formed by diffusing POCl ₃ from the contact hole.

  Next, in step S4, cesium ions are ion-implanted into the silicon oxide film 105 formed on the light incident side surface of the p-type silicon substrate 101.

  Next, in step S5, the p-type silicon substrate 101 after the cesium ion implantation is heated to 900 ° C., whereby surface inversion is performed on the light incident side surface region of the p-type silicon substrate 101 in contact with the silicon oxide film 105. Layer 103 is formed.

  After that, in step S6, the p-type silicon substrate 101 on which the electrode 107 is formed is annealed in a hydrogen atmosphere through a contact hole provided in the stacked body of the silicon oxide film 105 and the silicon nitride film 106, as shown in FIG. A sample of the photoelectric conversion device having the configuration is manufactured.

FIG. 16 shows the results of a composition analysis performed in the vicinity of the interface between the silicon oxide film 105 and the p-type silicon substrate 101 of the sample of the photoelectric conversion device having the configuration shown in FIG. Here, the results shown in FIG. 16 indicate that the concentration of cesium 104 in the entire silicon oxide film 105 is changed variously (2 × 10 ¹⁵ cm ⁻² , 1 × 10 ¹⁴ cm ⁻² and 5 × 10 ¹³ cm ⁻² ). The results are obtained when the composition analysis in the vicinity of the interface between the silicon oxide film 105 and the p-type silicon substrate 101 is performed by high resolution RBS (Rutherford Back Scattering).

Note that the horizontal axis in FIG. 16 indicates the distance (nm) from the interface between the silicon oxide film 105 and the p-type silicon substrate 101 of the sample of the photoelectric conversion device having the configuration shown in FIG. 14, and the vertical axis indicates the cesium concentration ( × 10 ²¹ cm ^-3 ), silicon concentration (atomic%) and oxygen concentration (atomic%) are shown.

  As shown in FIG. 16, in any case where the concentration of cesium 104 in the entire silicon oxide film 105 is changed variously, the interface between the silicon oxide film 105 and the p-type silicon substrate 101 moves to the silicon oxide film 106 side. Most of the cesium 104 exists within the distance of 5 nm and the distance to the p-type silicon substrate 101 side, and the ionized cesium 104 is in the vicinity of the interface between the silicon oxide film 105 and the p-type silicon substrate 101. It can be seen that segregation occurs.

FIG. 17 shows a cesium segregation amount (cm ⁻² ) in the vicinity of the interface between the silicon oxide film 105 and the p-type silicon substrate 101 of the sample of the photoelectric conversion device having the configuration shown in FIG. The relationship with the electron surface density (cm ^<-2> ) of the electron inversion layer induced on the surface of 101 is shown. Here, the horizontal axis of FIG. 17 indicates the dose amount of cesium ions implanted into the silicon oxide film 105, and the vertical axis of FIG. 17 indicates cesium in the vicinity of the interface between the silicon oxide film 105 and the p-type silicon substrate 101. ² and the electron surface density (cm ⁻² ) of the electron inversion layer induced on the surface of the p-type silicon substrate 101 by the segregation of cesium.

In addition, the results shown in FIG. 17 indicate that the dose of cesium ions implanted into the silicon oxide film 105 is variously changed to produce a sample of the photoelectric conversion device having the configuration shown in FIG. The electron surface density of the electron inversion layer is measured. Moreover, the segregation amount of cesium shown in FIG. 17 is calculated based on the result shown in FIG. Also, the results shown in FIG. 17 indicate that the boron concentration of the p-type silicon substrate 101 is changed (6.5 × 10 ¹⁴ cm ⁻³ , 2.9 × 10 ¹⁶ cm ⁻³ , 1.4 × 10 ¹⁷ cm ^−3). And 6.6 × 10 ¹⁷ cm ⁻³ ).

As shown in FIG. 17, as the dose of cesium ions implanted into the silicon oxide film 105 increases, the electron surface density (cm ⁻² ) of the electron inversion layer induced on the surface of the p-type silicon substrate 101. However, when the dose of cesium ions reaches 2 × 10 ¹⁴ cm ⁻² or more, the electron surface density (cm ⁻² ) of the electron inversion layer is almost constant (about 2 × 10 ¹³ cm ⁻² ). It turns out that it becomes.

Further, as the dose of cesium ions implanted into the silicon oxide film 105 increases, the amount of segregation (cm ⁻² ) of cesium near the interface between the silicon oxide film 105 and the p-type silicon substrate 101 also increases. However, when the dose of cesium ions exceeds a certain level, the amount of segregation (cm ⁻² ) of cesium becomes substantially constant.

Therefore, p-type electron surface density of the electron inversion layer induced in the surface of the silicon substrate 101 (cm ^-2) and cesium segregation amount (cm ^-2) is shown together similar behavior in between these Since it is considered that there is a correlation, the electron surface density (cm ⁻² ) of the electron inversion layer induced on the surface of the p-type silicon substrate 101 can be controlled by the segregation amount (cm ⁻² ) of cesium. Conceivable.

Moreover, by setting the value at which the electron surface density (cm ⁻² ) of the electron inversion layer induced on the surface of the p-type silicon substrate 101 is substantially constant as the electron surface density of the electron inversion layer optimum for the photoelectric conversion device, A wide process margin for obtaining an optimum electron surface density of the electron inversion layer in the photoelectric conversion device of the present invention can be ensured, and the electron surface density of the electron inversion layer can be controlled with high accuracy. .

FIG. 18 shows a dose amount (cm ⁻² ) of cesium ions ion-implanted into the silicon oxide film 105 of the sample of the photoelectric conversion device having the configuration shown in FIG. 14 and the surface of the p-type silicon substrate 101 on which electrons are induced. The relationship with the sheet resistance (kΩ / □) is shown. Here, the horizontal axis of FIG. 18 indicates the dose of cesium ions implanted into the silicon oxide film 105, and the vertical axis of FIG. 18 indicates the sheet of the electron inversion layer induced on the surface of the p-type silicon substrate 101. Resistance (kΩ / □) is shown. Further, the results shown in FIG. 18 indicate that the boron concentration of the p-type silicon substrate 101 is changed (4.6 × 10 ¹⁴ cm ⁻³ , 2.9 × 10 ¹⁶ cm ⁻³ , 1.4 × 10 ¹⁷ cm ^−3). And 6.6 × 10 ¹⁷ cm ⁻³ ).

As shown in FIG. 18, as the dose of cesium ions implanted into the silicon oxide film 105 increases, the sheet resistance (kΩ / □) of the electron inversion layer induced in the p-type silicon substrate 101 decreases. However, when the dose of cesium ions exceeds a certain level (2 × 10 ¹⁴ cm ⁻² or more), the sheet resistance (kΩ / □) of the electron inversion layer on the surface of the p-type silicon substrate 101 is almost constant (about 2 kΩ / □). Also here, by setting the value at which the sheet resistance of the electron inversion layer on the surface of the p-type silicon substrate 101 is substantially constant as the sheet resistance optimum for the photoelectric conversion device, the sheet resistance optimum for the photoelectric conversion device of the present invention is obtained. A wide process margin to obtain can be ensured, and the sheet resistance can be controlled with high accuracy.

FIG. 19 shows the relationship between the electron surface density (cm ⁻² ) and the temperature (K) of the electron inversion layer induced on the surface of the p-type silicon substrate 101 of the sample of the photoelectric conversion device having the configuration shown in FIG. Here, the horizontal axis of FIG. 19 represents temperature (K), and the vertical axis of FIG. 19 represents the electron surface density (cm ⁻² ) of the electron inversion layer induced on the surface of the p-type silicon substrate 101. Further, the results shown in FIG. 19 show that the dose of cesium ions implanted into the silicon oxide film 105 is changed (5 × 10 ¹³ cm ⁻² , 5 × 10 ¹⁴ cm ⁻² and 2 × 10 ¹⁵ cm ^−2). ).

As shown in FIG. 19, as the temperature (K) increases, the electron surface density (cm ⁻² ) of the electron inversion layer induced on the surface of the p-type silicon substrate 101 decreases. This indicates a temperature dependence opposite to that of an n + layer formed by a normal dopant such as phosphorus or arsenic doped in silicon.

  FIG. 20A shows an energy band diagram in the vicinity of the interface between the p-type silicon substrate and the silicon oxide film before the impurities present at the interface between the p-type silicon substrate and the silicon oxide film are ionized. FIG. 20B shows an energy band diagram in the vicinity of the interface between the p-type silicon substrate and the silicon oxide film after the impurities present at the interface between the p-type silicon substrate and the silicon oxide film are ionized.

In FIG. 20A, an impurity exists at the interface between the silicon oxide film and the p-type silicon substrate, and the impurity forms an impurity level 200. Impurity level 200 is formed at a position of −E _A above the lower end of the conduction band of the p-type silicon substrate (E _A represents activation energy of electron carrier generation by the impurity). When such a state is formed, as shown in FIG. 20B, electrons are emitted from the impurity level 200 to the p-type silicon substrate, and the vacant impurity level behaves as a positive charge (impurity is reduced). Ionize). Then, due to the electric field due to the positive charge, the energy band of the p-type silicon substrate is bent in the vicinity of the interface between the silicon oxide film and the p-type silicon substrate, and an electron inversion layer is formed in the vicinity of the interface .

When the numerical calculation was performed based on the energy band diagrams shown in FIGS. 20A and 20B, the activation energy E _A of electron carrier generation by cesium as an impurity was −0.11 eV to −0.13 eV. And was found to be in particular -0.12 eV. That is, cesium existing in the vicinity of the interface between the silicon oxide film and the p-type silicon substrate forms an impurity level at a position of about 0.12 eV above the lower end of the conduction band of the p-type silicon substrate. It has been clarified that an electron inversion layer is formed on the surface of the p-type silicon substrate by electron emission.

In FIG. 19, the alternate long and short dash line shows the behavior when the activation energy E _A of electron carrier generation by cesium as an impurity is −0.13 eV, and the solid line shows the activation energy E _A of −0.12 eV. shows the behavior of the case where, although the broken line is the activation energy E _a indicates the behavior when an -0.11EV, the activation energy E _a for the electron carrier generation by cesium as an impurity is -0. The behavior in the case of 11 eV to -0.13 eV, particularly in the case of -0.12 eV, matches the result shown in FIG.

21 to 25, the electron surface density (cm) of the electron inversion layer in the vicinity of the interface between the silicon oxide film and the p-type silicon substrate in the configuration of the energy band diagram shown in FIGS. 20 (a) and 20 (b), respectively. ^-2 ) and the surface density (cm ^-2 ) of impurities present at the interface between the silicon oxide film and the p-type silicon substrate.

Here, in FIG. 21 to FIG. 25, the horizontal axis indicates the surface density (cm ⁻² ) of the impurity, and the vertical axis indicates the electron surface density (cm ⁻² ) of the electron inversion layer. . FIGS. 21 to 25 show the interface between the silicon oxide film and the p-type silicon substrate when the activation energy E _A is sequentially changed by −0.02 eV from −0.00 eV to −0.20 eV. relationship surface density of existing impurities and (cm ^-2) and electron surface density of the electron inversion layer (cm ^-2) is indicated by lines. From the results of the above-described experiment, the case where cesium is used as the impurity corresponds to the case of E _A ≈−0.12 eV.

FIG. 21 shows the relationship when the boron concentration in the p-type silicon substrate is 1 × 10 ¹⁶ cm ⁻³ , and FIG. 22 shows that the boron concentration in the p-type silicon substrate is 1 × 10 ¹⁷ cm ⁻³ . FIG. 23 shows the relationship when the boron concentration in the p-type silicon substrate is 1 × 10 ¹⁸ cm ⁻³ . FIG. 24 shows the relationship when the boron concentration in the p-type silicon substrate is 3 × 10 ¹⁸ cm ⁻³ , and FIG. 25 shows the boron concentration in the p-type silicon substrate being 6 × 10 ¹⁸ cm ⁻³ . Shows the relationship.

  In addition, the hatched portion in FIGS. 21 to 25 represents a range showing excellent characteristics as a photoelectric conversion device. That is, if the upper limit of the range of the hatched portion is exceeded, the electron surface density of the electron inversion layer becomes too large, and the surface of the p-type silicon substrate becomes metallic, making it difficult for light to enter, and the characteristics deteriorate. If the lower limit of the range is not reached, the electron inversion density of the electron inversion layer becomes too small, the resistance increases, and the characteristics deteriorate.

As shown in FIGS. 21 to 25, when the impurity is cesium (E _A ≈−0.12 eV), regardless of the boron concentration in the p-type silicon substrate, the surface density of the impurity ( cm ⁻² ) and the electron surface density (cm ⁻² ) of the electron inversion layer do not match. Conventionally, it was thought that all cesium in the silicon oxide film was ionized. Therefore, the surface density (cm ⁻² ) of cesium existing at the interface between the silicon oxide film and the p-type silicon substrate and the ionized cesium (positive) It has been considered that the surface density (cm ⁻² ) of the (fixed charge of) is in agreement. Here, the surface density of ionized cesium is expressed as the sum of the electron surface density of the electron inversion layer induced in the p-type silicon substrate and the space charge density in the depletion layer formed on the surface of the p-type silicon substrate. When the boron concentration in the p-type silicon substrate is low, or when the electron surface density (cm ⁻² ) of the electron inversion layer is sufficiently high, the surface density (cm ⁻² ) of cesium existing at the interface and p The electron surface density (cm ⁻² ) of the electron inversion layer induced in the silicon substrate is almost the same. However, in the shaded area shown in FIGS. 21 to 25, the surface density (cm ⁻² ) of the ionized cesium is smaller than the electron surface density (cm ⁻² ) of the electron inversion layer. as can be seen from the fact that there, in order to obtain electron surface density of the electron inversion layer to desired (cm ^-2), the surface density of the cesium present at the interface between the silicon oxide film and the p-type silicon substrate (cm ^-2 ) Needs to be introduced into the silicon oxide film so as to be higher than the desired electron surface density (cm ⁻² ) of the electron inversion layer.

  In FIG. 26 (a), as in the conventional patent document 1, a silicon oxide film is formed on the surface of a p-type silicon substrate, a silicon nitride film is formed on the silicon oxide film, and a silicon nitride film, a silicon oxide film, The energy band figure when the impurity which becomes a positive fixed charge is arrange | positioned in the interface of this is shown. Further, as in the sample of the photoelectric conversion device having the configuration shown in FIG. 14 in FIG. 26B, a silicon oxide film is formed on the surface of the p-type silicon substrate, and the interface between the silicon oxide film and the p-type silicon substrate is positive. The energy band figure when the impurity used as the fixed charge is arranged.

  In general, when electrons move between the level of an impurity that becomes a positive fixed charge and a p-type silicon substrate, and there is an impurity with a sufficient density, the impurity that becomes a positive fixed charge Electron movement occurs until the level substantially matches the Fermi level of the p-type silicon substrate.

However, as shown in FIG. 26A, when a silicon oxide film exists between an impurity that becomes a positive fixed charge and the p-type silicon substrate, positive fixation is caused by a potential gradient in the silicon oxide film. activation energy -E _a impurity serving as a charge is effectively increased (the position of the level 201 of the impurities which become positive fixed charges drops effective). This reduces the electron surface density of the inversion layer on the surface of the p- type silicon substrate.

On the other hand, when the silicon oxide film directly formed on the surface of the p-type silicon substrate has an impurity that becomes a positive fixed charge at the interface with the surface of the p-type silicon substrate as shown in FIG. since the dielectric film interposed unlike the case of 26 (a) is not present, the effective increase in the activation energy -E _a impurities which become positive fixed charges does not occur. Therefore, in this case, the electron surface density of the inversion layer on the surface of the p- type silicon substrate is not reduced.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The photoelectric conversion device of the present invention may be suitably used for, for example, a solar battery.

(A) is a typical top view of the surface of the light-incidence side of an example of the photoelectric conversion apparatus of this invention, (b) is typical sectional drawing along 1b-1b of (a), c) is a schematic cross-sectional view along 1c-1c of (a). (A) is a typical top view of the surface of the light-incidence side of another example of the photoelectric conversion apparatus of this invention, (b) is typical sectional drawing along 2b-2b of (a). (C) is typical sectional drawing which followed 2c-2c of (a). (A) is a typical top view of the surface of the light-incidence side of another example of the photoelectric conversion apparatus of this invention, (b) is typical sectional drawing along 3b-3b of (a). (C) is typical sectional drawing which followed 3c-3c of (a). (A) is a typical top view of the surface of the light-incidence side of another example of the photoelectric conversion apparatus of this invention, (b) is typical sectional drawing along 4b-4b of (a). (C) is typical sectional drawing which followed 4c-4c of (a). It is typical sectional drawing of another example of the photoelectric conversion apparatus of this invention. It is typical sectional drawing of another example of the photoelectric conversion apparatus of this invention. It is typical sectional drawing of another example of the photoelectric conversion apparatus of this invention. It is typical sectional drawing of another example of the photoelectric conversion apparatus of this invention. It is typical sectional drawing of another example of the photoelectric conversion apparatus of this invention. It is a typical perspective view of another example of the photoelectric conversion apparatus of this invention. It is a typical perspective view of another example of the photoelectric conversion apparatus of this invention. It is typical sectional drawing of another example of the photoelectric conversion apparatus of this invention. It is typical sectional drawing illustrating a part of process of an example of the manufacturing method of the photoelectric conversion apparatus of the structure shown in FIG. It is typical sectional drawing of the sample of the photoelectric conversion apparatus produced in the Example of this invention. 15 is a flowchart of a method for manufacturing a sample of the photoelectric conversion device having the configuration illustrated in FIG. It is a figure which shows the result of having performed the composition analysis of the interface vicinity of the silicon oxide film of a sample of the photoelectric conversion apparatus of a structure shown in FIG. 14, and a p-type silicon substrate. The amount of segregation of cesium in the vicinity of the interface between the silicon oxide film and the p-type silicon substrate of the sample of the photoelectric conversion device having the configuration shown in FIG. 14 and the electrons in the electron inversion layer induced on the surface of the p-type silicon substrate by the segregation of cesium It is a figure which shows the relationship with areal density. FIG. 15 is a diagram illustrating a relationship between a dose amount of cesium ions ion-implanted into a silicon oxide film of a sample of the photoelectric conversion device having the configuration illustrated in FIG. 14 and a sheet resistance of an electron inversion layer in which electrons of a p-type silicon substrate are induced. is there. It is a figure which shows the relationship between the electronic surface density of the electron inversion layer induced | guided | derived to the surface of the p-type silicon substrate of the sample of the photoelectric conversion apparatus of a structure shown in FIG. 14, and temperature. (A) is an energy band diagram in the vicinity of the interface between the p-type silicon substrate and the silicon oxide film in a state before the impurities existing at the interface between the p-type silicon substrate and the silicon oxide film are ionized. FIG. 4 is an energy band diagram in the vicinity of the interface between the p-type silicon substrate and the silicon oxide film in a state after impurities existing at the interface between the silicon substrate and the silicon oxide film are ionized. In the configuration of the energy band diagram shown in FIGS. 20A and 20B, the electron surface density (cm ⁻² ) of the electron inversion layer in the vicinity of the interface between the silicon oxide film and the p-type silicon substrate, and the p-type silicon It is a figure which shows the relationship with the surface density (cm ^<-2> ) of the impurity in the surface of a board | substrate. In the configuration of the energy band diagram shown in FIGS. 20A and 20B, the electron surface density (cm ⁻² ) of the electron inversion layer in the vicinity of the interface between the silicon oxide film and the p-type silicon substrate, and the p-type silicon It is a figure which shows the relationship with the surface density (cm ^<-2> ) of the impurity in the surface of a board | substrate. In the configuration of the energy band diagram shown in FIGS. 20A and 20B, the electron surface density (cm ⁻² ) of the electron inversion layer in the vicinity of the interface between the silicon oxide film and the p-type silicon substrate, and the p-type silicon It is a figure which shows the relationship with the surface density (cm ^<-2> ) of the impurity in the surface of a board | substrate. In the configuration of the energy band diagram shown in FIGS. 20A and 20B, the electron surface density (cm ⁻² ) of the electron inversion layer in the vicinity of the interface between the silicon oxide film and the p-type silicon substrate, and the p-type silicon It is a figure which shows the relationship with the surface density (cm ^<-2> ) of the impurity in the surface of a board | substrate. In the configuration of the energy band diagram shown in FIGS. 20A and 20B, the electron surface density (cm ⁻² ) of the electron inversion layer in the vicinity of the interface between the silicon oxide film and the p-type silicon substrate, and the p-type silicon It is a figure which shows the relationship with the surface density (cm ^<-2> ) of the impurity in the surface of a board | substrate. (A) shows a conventional method in which a silicon oxide film is formed on the surface of a p-type silicon substrate, a silicon nitride film is formed on the silicon oxide film, and a silicon nitride film, a silicon oxide film, FIG. 15B is an energy band diagram when an impurity serving as a positive fixed charge is arranged at the interface of FIG. 14B, and FIG. Is an energy band diagram when an impurity that becomes a positive fixed charge is disposed at the interface between the silicon oxide film and the p-type silicon substrate.

Explanation of symbols

  1 p + layer, 2 p-type silicon substrate, 2a first amorphous silicon layer, 2b second amorphous silicon layer, 2c third amorphous silicon layer, 3,102 n + layer, 4,103 surface inversion layer, 4a 1st inversion layer, 4b 2nd inversion layer, 4c 3rd inversion layer, 4d 4th inversion layer, 5,104 Cesium, 6, 6a, 6b, 6c, 26, 60 Silicon oxide film, 7 Back electrode , 8 metal electrode, 9 transparent conductive film, 10 metal silicide, 11 edge portion, 12a, 12b thin film silicon layer, 13 accumulation layer, 15 unevenness, 16 p-type semiconductor layer, 17 n-type semiconductor layer, 18 n-type electrode, 19 p-type electrode, 40 back surface inversion layer, 20, 21, 50 impurities, 51 first photoelectric conversion layer, 52 second photoelectric conversion layer, 53 third photoelectric conversion layer, 101 p-type silicon Substrate, 105 silicon oxide film, 106 silicon nitride film, 107 electrode, 200, 201 impurity level, 202 level.

Claims (18)

A semiconductor layer;
A dielectric film disposed so as to be in contact with the surface of the semiconductor layer,
The dielectric film, the vicinity of the interface between the semiconductor layer, and organic impurities as a positive fixed charge,
The semiconductor layer is made of crystalline silicon, amorphous silicon or microcrystalline silicon,
The photoelectric conversion device , wherein the impurity is cesium . The locations where the impurities are most present are a region that advances from the interface between the semiconductor layer and the dielectric film to the semiconductor layer side by 5 nm in a direction perpendicular to the interface, and 5 nm on the dielectric film side. It characterized that you located in the region between the SusumuMukai regions, photoelectric conversion device according to claim 1. Wherein at least a portion of the region of the surface of the dielectric film is in contact the semiconductor layer, and wherein the Rukoto which have a inversion layer or accumulation layer, the photoelectric conversion device according to claim 1 or 2. The photoelectric conversion device according to claim 3 , further comprising an electron collection region in contact with the inversion layer or the accumulation layer . The photoelectric conversion device according to claim 4 , wherein the electron collection region is an n-type region . 6. The photoelectric conversion device according to claim 5 , wherein at least one selected from the group consisting of metal, metal silicide, and a transparent conductive film is provided in at least a part of the region on the n-type region. . 5. The photoelectric conversion device according to claim 4 , wherein the electron collection region is at least one selected from the group consisting of a metal, a metal silicide, and a transparent conductive film . 8. The photoelectric conversion according to claim 1 , wherein a hole collecting region is provided in at least a part of a region of the surface of the semiconductor layer opposite to a side in contact with the dielectric film. 9. apparatus. A second dielectric film disposed so as to be in contact with the surface of the semiconductor layer opposite to the side in contact with the dielectric film;
The photoelectric conversion device according to claim 1, wherein the second dielectric film has an impurity that becomes a negative fixed charge in the vicinity of an interface with the semiconductor layer . The impurity that becomes the negative fixed charge includes at least one selected from the group consisting of boron, aluminum, gallium, indium, platinum, fullerene fluoride, fullerene oxide, fluorine, chlorine, bromine, and iodine. The photoelectric conversion device according to claim 9 . The dielectric film side light is incident from the conductivity type of the semiconductor layer is characterized by a p-type Der Rukoto photoelectric conversion device according to any one of claims 1 to 10. 11. The photoelectric conversion device according to claim 1, wherein light is incident from a side opposite to the dielectric film, and a conductivity type of the semiconductor layer is n-type . The photoelectric conversion device according to claim 1, wherein the dielectric film has a band gap of 4.2 eV or more . 14. The photoelectric conversion device according to claim 1, wherein the dielectric film is made of at least one selected from the group consisting of silicon oxide, silicon oxynitride, and silicon nitride . The photoelectric conversion device according to claim 1, wherein unevenness is formed on a surface of the semiconductor layer. A first photoelectric conversion layer;
A second photoelectric conversion layer,
The first photoelectric conversion layer is an impurity that is placed in contact with the surface of the first semiconductor layer and the first semiconductor layer and becomes a positive fixed charge in the vicinity of the interface between the first semiconductor layer and the first semiconductor layer. A surface dielectric film having a certain cesium; an n-type surface inversion layer disposed in at least a part of a surface region of the first semiconductor layer in contact with the surface dielectric film; and A p-type impurity-containing layer having p-type impurities on the back surface opposite to the front surface;
The second photoelectric conversion layer includes a second semiconductor layer, an n-type impurity-containing layer having an n-type impurity on the surface of the second semiconductor layer, and a surface opposite to the surface of the second semiconductor layer. A p-type impurity-containing layer having a p-type impurity on the back surface,
The first photoelectric conversion layer and the second photoelectric conversion layer are formed by bonding the p-type impurity-containing layer of the first photoelectric conversion layer and the n-type impurity-containing layer of the second photoelectric conversion layer. Have a laminated structure in which
The photoelectric conversion device, wherein the first semiconductor layer and the second semiconductor layer are made of crystalline silicon, amorphous silicon, or microcrystalline silicon. A first semiconductor layer;
A first dielectric film bonded to the surface of the first semiconductor layer;
A second dielectric film bonded to the back surface of the first semiconductor layer;
A second semiconductor layer bonded to the back surface of the second dielectric film,
The first dielectric film has cesium which is an impurity that becomes a positive fixed charge in the vicinity of the interface with the first semiconductor layer,
The second dielectric film has an impurity that becomes a negative fixed charge in the vicinity of the interface with the first semiconductor layer and in the vicinity of the interface with the second semiconductor layer,
The photoelectric conversion device, wherein the first semiconductor layer and the second semiconductor layer are made of crystalline silicon, amorphous silicon, or microcrystalline silicon. The impurity that becomes the negative fixed charge includes at least one selected from the group consisting of boron, aluminum, gallium, indium, platinum, fullerene fluoride, fullerene oxide, fluorine, chlorine, bromine, and iodine. The photoelectric conversion device according to claim 17.

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