JP2014110334A - Method of diffusing dopant and method of manufacturing electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of diffusing dopants that can be efficiently added in a simple method to a material selected from a semiconductor and an electrode.SOLUTION: The method of diffusing dopants includes: contacting a second material 2 containing dopants to a first material 1 selected from a semiconductor and an electrode; transferring dopants contained in the second material 2 to the first material 1 by performing a heat treatment in a state where both materials are in contact with each other; and then separating the second material 2 from the first material 1.

Description

  The present invention relates to a dopant diffusion method and an electronic device manufacturing method using the method.

  In general, the characteristics of electronic devices are improved by adding a dopant to a semiconductor or an electrode.

For example, in a chalcopyrite solar cell using a chalcopyrite-structured semiconductor such as CuInSe ₂ or Cu (In, Ga) Se _{2 in the} photoelectric conversion layer, conversion efficiency is improved by adding Na as a dopant to the photoelectric conversion layer. It is known to improve.

  As one method of adding Na to the photoelectric conversion layer, there is a method of simultaneously depositing a Na compound such as NaF and adding Na to the photoelectric conversion layer when the photoelectric conversion layer is formed by sputtering.

  However, a chalcopyrite-structured semiconductor needs to be formed by controlling a plurality of elements with high precision. In this method, there is a problem that it becomes more complicated to control the amount of each element added during film formation. It was.

  As another method, there is a method of using a soda lime glass substrate and diffusing Na in the substrate into the photoelectric conversion layer in the course of film formation.

  However, in this method, since the substrate is limited to soda lime glass, the freedom of substrate selection is lost.

  As another method, there is a method in which a soda lime glass thin film is formed on a substrate or a back electrode, and Na in the soda lime glass thin film is diffused into the photoelectric conversion layer in the process of forming the photoelectric conversion layer.

  However, the soda lime glass thin film has a slow film formation speed and further requires a separate process for forming the soda lime glass thin film, which increases the number of processes and decreases the productivity of the electronic device. In addition, when the soda lime glass thin film is interposed between the layers, the adhesion between the back electrode and the substrate or the photoelectric conversion layer is easily lowered.

  As another method, there is a method in which a Na-containing thin film such as NaF is formed on the back electrode or the photoelectric conversion layer, and heat treatment or the like is performed to diffuse Na in the Na-containing thin film to the photoelectric conversion layer.

  However, since many Na-containing thin films such as NaF often have hygroscopicity, deliquescence, etc., there is a risk that the Na-containing thin film may be altered and adversely affect the photoelectric conversion layer, transparent electrode, and the like. It was. In addition, since a separate step of forming the Na-containing thin film is necessary, the number of steps is increased and the productivity of the electronic device is lowered. Moreover, when the Na-containing thin film is interposed between the layers, the adhesion between the back electrode or the transparent electrode and the photoelectric conversion layer is likely to be lowered.

  As another method, as described in Patent Document 1, a back electrode is formed using an electrode material containing Na and Mo, and Na in the back electrode is formed in the process of forming a photoelectric conversion layer. There is a method of diffusing into the photoelectric conversion layer.

  However, when the back electrode is formed using an electrode material containing Mo and Na, if the Na content of the back electrode is increased, the electrode becomes brittle and the workability tends to be lowered. In order to improve the workability, it is desirable to reduce the Na content of the electrode as much as possible. However, in order to contain Na necessary for adding to the photoelectric conversion layer or the like in the back electrode, the thickness of the back electrode is increased. There is a need to. Since Mo has a high resistance value and is an expensive material, it is not desirable to increase the thickness of the Mo electrode from the viewpoint of the electrical characteristics and material cost of the electronic device.

JP 2009-283508 A

  An object of the present invention is to provide a dopant diffusion method in which a dopant can be efficiently added to a material selected from a semiconductor and an electrode by a simple method, and to manufacture an electronic device having improved characteristics by adding a dopant to a semiconductor layer. It is to provide a method.

  In order to achieve the above object, the dopant diffusion method of the present invention is such that a first material selected from a semiconductor and an electrode is brought into contact with a second material containing a dopant, and heat treatment is performed in a state in which both materials are in contact with each other. After the dopant contained in the second material is transferred to the first material, the second material is separated from the first material.

  In the dopant diffusion method of the present invention, after the second material is separated from the first material, a third material selected from a semiconductor and an electrode is laminated on the first material, and heat treatment is performed. preferable.

  In the dopant diffusion method of the present invention, it is preferable that the first material is an electrode and the third material is a semiconductor. In this aspect, the first material is an electrode in which a metal layer containing Mo is disposed on the third material side, and the third material is Cu, In and / or Ga, Se and / or A semiconductor containing at least S, or a semiconductor containing at least Cu, Zn, Sn, Se and / or S is preferable.

  In the dopant diffusion method of the present invention, the dopant is preferably an alkali metal.

  The method for manufacturing an electronic device according to the present invention includes a substrate, a first electrode, a semiconductor layer, and a second electrode laminated on the substrate, wherein the first electrode and the second electrode In the method of manufacturing an electronic device in which the semiconductor layer is disposed between the first electrode, the material containing the dopant is brought into contact with the first electrode, and the dopant contained in the material is subjected to heat treatment in a state where both are in contact with each other. After the transition to the first electrode, the material is separated from the first electrode, and then the semiconductor layer is formed on the first electrode, and heat treatment is performed during or after the formation of the semiconductor layer. It is characterized by.

  In the electronic device manufacturing method of the present invention, the first electrode is an electrode in which a metal layer containing Mo is disposed on the semiconductor layer side, and the semiconductor layer is formed of Cu, In and / or Ga, and Se. And / or a semiconductor containing at least S, or a semiconductor containing at least Cu, Zn, Sn, Se and / or S.

  According to the present invention, the first material selected from the semiconductor and the electrode is brought into contact with the second material containing the dopant, and the heat treatment is performed in a state in which both are brought into contact, whereby the dopant contained in the second material is It diffuses and moves to the first material side by heat. Then, after the dopant is transferred to the first material, the second material is separated from the first material, whereby the first material to which the dopant is added is obtained. The second material containing the dopant can be used repeatedly after being separated from the first material.

  Thus, in the present invention, since it is not necessary to form the first material on a substrate containing a dopant such as a soda lime glass substrate, the substrate is highly flexible and versatile. Moreover, since it is not necessary to form a thin film for adding a dopant, such as a soda lime glass thin film or a Na-containing thin film, on the first material, a layer made of another material on the first material. Can be laminated with good adhesion. In addition, when an electrode is formed using an electrode material containing a dopant, the dopant concentration may not be increased due to the problem of electrode processability, which increases the thickness of the electrode, leading to conductivity and material cost. However, according to the present invention, the dopant concentration can be sufficiently increased even if the first material is thin. Moreover, in this invention, since a dopant can be added to a 1st material with a dry process, a dopant can be efficiently added also to the electronic device from which a characteristic deteriorates, for example with a water | moisture content.

It is process drawing which shows 1st Embodiment of the diffusion method of the dopant of this invention. It is process drawing which shows 2nd Embodiment of the diffusion method of the dopant of this invention. It is process drawing of the manufacturing method of the electronic device of this invention.

  1st Embodiment of the diffusion method of the dopant of this invention is described using FIG.

  As shown to Fig.1 (a), the 2nd material 2 containing the dopant 5 is made to contact the 1st material 1 chosen from the semiconductor and the electrode. Note that the first material 1 may be an electrode or a single layer of a semiconductor, or may be a stacked body of a semiconductor and an electrode.

  Although the kind of dopant 5 changes with electronic devices, alkali metals, such as Na, K, and Li, are preferable and Na is especially preferable.

  The type of the second material 2 including the dopant 5 is not particularly limited. For example, (1) soda is applied to the surface of a heat-resistant substrate such as a glass substrate, a metal substrate, a polyamide substrate, a polyimide substrate, or a ceramic substrate. A thin film containing a dopant such as a lime glass thin film or NaF thin film, (2) Mo, Ag, Cu, Au, Al, Mg, W, Co, Zn, Ni and alloys thereof, ceramics, silicon, etc. Examples of the base material include a material obtained by adding a dopant to the base material and formed into a plate shape or the like, and (3) a substrate containing a dopant such as a soda lime glass substrate.

  The dimension of the contact side surface of the second material 2 is preferably the same as or larger than the dimension of the contact side surface of the first material 1. According to this, since the 2nd material 2 can be made to contact the whole surface of the contact side of the 1st material 1, a dopant can be uniformly added to the surface direction of the 1st material 1.

  Next, as shown in FIG. 1B, heat treatment is performed while maintaining the state in which the second material 2 is in contact with the first material 1. By doing so, a large amount of the dopant existing in the crystal grain boundary of the second material 2 is diffused and transferred to the first material 1 side by heat, and the dopant 5 is added to the first material 1.

  Although heating conditions change with kinds of the 1st material 1, generally it is preferable to carry out at 100-600 degreeC for 10 to 60 minutes. In particular, when the outermost layer of the first material 1 is formed of a metal layer containing Mo, it is preferably performed at 100 to 600 ° C. for 10 to 60 minutes, and at 300 to 450 ° C. for 10 to 30 minutes. Is more preferable. When the heating temperature is less than 100 ° C., the diffusion rate of the dopant is slow, and it is necessary to set the heating time longer. If the heating temperature exceeds 600 ° C., the first material 1 may be thermally damaged. If the heating time is less than 10 minutes, the dopant may not be sufficiently added to the first material 1. When the heating time exceeds 60 minutes, productivity tends to decrease.

  The heat treatment may be performed in any of an air atmosphere, a vacuum atmosphere, and an inert gas atmosphere. Preferably, the heat treatment is performed in a vacuum atmosphere or an inert gas atmosphere because surface oxidation of the material containing the dopant can be reduced.

  After performing the heat treatment, the second material 2 is separated from the first material 1 as shown in FIG. Thus, the first material 1 to which the dopant 5 is added is obtained.

  When the dopant content of the first material 1 is insufficient, the second material 2 is brought into contact with the first material 1 and heat treatment is performed, and then the second material 2 is separated from the first material 1. May be repeated. Further, the heat treatment time may be set longer.

  A second embodiment of the dopant diffusion method of the present invention will be described with reference to FIG.

  The steps up to the steps of FIGS. 2A to 2C are the same as in the above embodiment. That is, as shown in FIG. 2A, the second material 2 containing the dopant 5 is brought into contact with the first material 1. Next, as shown in FIG.2 (b), heat processing is performed, maintaining the state which made both contact. Next, after the heat treatment, the second material 2 is separated from the first material 1 as shown in FIG.

  In this embodiment, after separating the second material 2 from the first material 1, as shown in FIG. 2D, the third material 3 is laminated on the first material 1 and heat treatment is performed. The heat treatment may be performed simultaneously with the lamination of the third material 3, or may be performed after the lamination. By doing so, as shown in FIG. 2 (e), a large amount of dopant present at the grain boundaries of the first material 1 diffuses and migrates to the third material 3 side due to heat and moves to the third material 3. Dopant 5 can be added. As described above, in this embodiment, the dopant 5 added to the first material 1 is transferred to the third material 3 after the dopant 5 is transferred from the second material 2 to the first material 1. The dopant 5 contained in the second material 2 can be added to the third electrode 3 without directly contacting 2 with the third material 3. For this reason, it is preferable to refrain from contacting members other than electronic device components, such as semiconductors, in consideration of damage, deterioration of characteristics, etc. The dopant can be added without contacting the material.

Examples of the third material 3 include a semiconductor and an electrode, and a semiconductor is preferable. As the semiconductor, CuInSe ₂ , CuInS ₂ , CuGaSe ₂ , CuGaS ₂ , Cu (In, Ga) Se ₂ , Cu (In, Ga) S ₂ , Cu (In, Ga) (S, Se) _2, etc. A semiconductor having a chalcopyrite structure containing at least In and / or Ga and Se and / or S, Cu ₂ ZnSnS ₄ , Cu ₂ ZnSnSe ₄ , Cu ₂ ZnSn (S, Se) ₄ , Cu, A semiconductor having a stannite structure or a kesterite structure containing at least Zn, Sn, Se and / or S is preferred. In these semiconductors, the addition of a dopant improves the characteristics of the electronic device, such as improving the conversion efficiency of the solar cell.

  In this embodiment, the first material 1 is preferably an electrode, and an electrode in which a metal layer containing Mo (hereinafter also referred to as Mo layer) is disposed on the third material 3 side is particularly preferable. According to this, corrosion resistance to Se or the like can be obtained, and corrosion degradation of the first material 1 can be prevented when the semiconductor layer is formed on the first material 1.

Moreover, it is preferable that the Mo layer is laminated | stacked on the metal layer (henceforth a low resistance metal layer) containing the electrically-conductive material whose electric resistivity is smaller than Mo. As the conductive material having an electrical resistivity smaller than that of Mo, a conductive material having an electrical resistivity at 20 ° C. of less than 5.3 × 10 ⁻⁸ Ω · m is preferable. By carrying out like this, the electrical resistivity of an electrode can be made smaller than the case where it comprises Mo alone. Specific examples of the low-resistance conductive material include Ag, Cu, Au, Al, Mg, W, and alloys thereof, and one or more of these can be preferably used.

  The film thickness of the Mo layer is preferably 70 nm or more, and more preferably 200 nm or more. If the film thickness of the Mo layer is too thin, even if the Mo layer is disposed on the outermost layer on the third material 3 side, the corrosion resistance to Se or the like may be reduced, which may hinder the manufacture of the electronic device. The film thickness of the Mo layer is preferably 1000 nm or less, and more preferably 600 nm or less. If the Mo layer is too thick, it will take a long time to form, resulting in poor productivity, and further, peeling tends to occur due to a stress difference with the substrate material.

  Next, the manufacturing method of the electronic device of this invention is demonstrated.

  In the electronic device manufacturing method of the present invention, the type of electronic device is not particularly limited. What is necessary is just to include a substrate, a first electrode, a semiconductor layer, and a second electrode laminated on the substrate, and the semiconductor layer is disposed between the first electrode and the second electrode. Specifically, a solar cell, an optical sensor, etc. are mentioned. Hereinafter, the method for manufacturing an electronic device of the present invention will be described in detail with reference to FIG. In this embodiment, the back electrode 12 corresponds to the “first electrode” in the present invention, the photoelectric conversion layer 14 corresponds to the “semiconductor layer” in the present invention, and the transparent electrode 16 corresponds to the “second electrode” in the present invention. Is equivalent to.

  First, as shown in FIG. 3A, the back electrode 12 is formed on the substrate 11. The method for forming the back electrode 12 is not particularly limited. It can be formed by a conventionally known method such as sputtering or vapor deposition.

  As for the back electrode 12, it is preferable that the outermost layer is formed with the metal layer (Mo layer) containing Mo, and it is more preferable that the Mo layer is laminated | stacked on the low resistance metal layer mentioned above. According to this, corrosion resistance with respect to Se or the like is obtained, and corrosion degradation of the back electrode 12 when the photoelectric conversion layer 14 is formed on the back electrode 12 can be prevented. And the electrical resistance of an electrode can be made smaller by laminating | stacking Mo layer on the low-resistance metal layer mentioned above.

  Next, as shown in FIG. 3B, a material containing a dopant (hereinafter referred to as a dopant-containing material) 13 is brought into contact with the surface of the back electrode 12. As the dopant-containing material 13, the same material as the second material 2 described in the above-described dopant diffusion method can be used.

  Next, heat treatment is performed while maintaining the state in which the back electrode 12 and the dopant-containing material 13 are in contact with each other. By performing the heat treatment in this manner, a large amount of dopant existing in the crystal grain boundary of the dopant-containing material 13 is diffused to the back electrode 12 side by heat.

  Although the heat treatment conditions vary depending on the material of the back electrode 12, for example, when the outermost layer of the back electrode 12 is formed of a metal layer containing Mo, 300 to 450 in a vacuum atmosphere or an inert gas atmosphere. It is preferable to carry out at 10 degreeC for 10 to 30 minutes. By performing the heat treatment in this manner, the dopant can be efficiently added to the back electrode 12.

  Next, as shown in FIG. 3C, the second material 13 is separated from the back electrode 12.

  Then, as illustrated in FIG. 3D, the photoelectric conversion layer 14, the buffer layer 15, and the transparent electrode 16 are sequentially formed on the back electrode 12. When the film formation temperature of each of the above layers is high, the photoelectric conversion layer 14 is heat-treated at the time of forming each layer. As a result, a large amount of dopant present in the crystal grain boundary of the back electrode 12 moves to the photoelectric conversion layer 14 by thermal diffusion, and the dopant is added to the photoelectric conversion layer 14. In addition, when the film-forming temperature of each layer is low and it is difficult to sufficiently heat the photoelectric conversion layer 14 at the time of forming each layer, the photoelectric conversion layer 14 is formed, and then heat treatment is performed so that the layer is included in the back electrode 12. The dopant to be transferred is transferred to the photoelectric conversion layer 14.

  The semiconductor constituting the photoelectric conversion layer 14 is not particularly limited, but a chalcopyrite structure semiconductor including at least Cu, In and / or Ga, Se and / or S, Zn, Sn, Se and A semiconductor having a stannite structure or a kesterite structure containing at least S and / or S is preferable. By using these semiconductors for the photoelectric conversion layer, a solar cell with high conversion efficiency can be obtained. In addition, since these semiconductors have a relatively high film formation temperature, the dopant contained in the back electrode 12 is moved to the photoelectric conversion layer 14 side during the film formation of the photoelectric conversion layer 14 without performing a separate heat treatment. Can be diffused.

As a semiconductor having a chalcopyrite structure including at least Cu, In and / or Ga, and Se and / or S, CuInSe ₂ , CuInS ₂ , CuGaSe ₂ , CuGaS ₂ , Cu (In, Ga) Se ₂ , Cu ( _{In, Ga) S 2, Cu} (In, Ga) (S, Se) 2 , and the like. This semiconductor can be formed by a method such as a selenization method or a multi-element simultaneous vapor deposition method. To describe Cu (In, Ga) Se ₂ as an example, in the selenization method, a precursor film containing Cu, In, and Ga is formed on the back electrode 12 by a method such as sputtering or vapor deposition. The precursor film can be formed by heat treatment in an atmosphere of H ₂ Se gas and / or H ₂ S gas. In the multi-source simultaneous vapor deposition method, a raw material containing Cu, In, Ga, and Se can be formed on the back electrode 12 by simultaneous vapor deposition.

Examples of the semiconductor having a stannite structure or a kesterite structure containing at least Cu, Zn, Sn, Se, and / or S include Cu ₂ ZnSnS ₄ , Cu ₂ ZnSnSe ₄ , and Cu ₂ ZnSn (S, Se) _4. It is done. This semiconductor can be formed by a conventionally known method such as a sulfidation method or a multi-source co-evaporation method. To describe Cu ₂ ZnSnS ₄ as an example, in the sulfurization method, a precursor film containing Cu, Zn, and Sn is formed on the back electrode 12 by a method such as sputtering or vapor deposition, and the precursor film is formed as H _2. It can be formed by heat treatment in an S gas atmosphere. In the multi-source simultaneous vapor deposition method, a raw material containing Cu, Zn, Sn, and S can be formed on the back electrode 12 by simultaneous vapor deposition.

  The film thickness of the photoelectric conversion layer 14 varies depending on the type. For example, in the case of a semiconductor having a chalcopyrite structure, 1.2 to 2.0 μm is preferable. In the case of a semiconductor having a stannite structure or a kesterite structure, 1.0 to 3.0 μm is preferable.

The buffer layer 15 is composed of an n-type transparent conductive film having a wide forbidden band. Specific _{compounds, CdS, ZnO, ZnS, Zn} (OH) 2, ZnInSe 2, ZnMgO, In 2 O 3, In 2 S 3 , and the like. The method for forming the buffer layer 15 is not particularly limited, and can be formed by a conventionally known method such as sputtering or vapor deposition.

The transparent electrode 16 _{is, ZnO, SnO 2, In 2} O 3, ITO, CdO, formed of a transparent conductive material such as Cd ₂ SnO 4, CdS. The method for forming the transparent electrode 16 is not particularly limited, and can be formed by a conventionally known method such as a sputtering method or a vapor deposition method.

  In addition, after forming the photoelectric converting layer 14, before forming the buffer layer 15, the dopant containing material 13 is made to contact the surface of the photoelectric converting layer 14, and it heat-processes, and then the dopant containing material from the photoelectric converting layer 14 is made. After separating 13, the buffer layer 15 and the transparent electrode 16 may be sequentially formed on the photoelectric conversion layer 14. By doing in this way, since a dopant can be added to the photoelectric converting layer 14 from the upper and lower surfaces of the photoelectric converting layer 14, many dopants can be added to the photoelectric converting layer 14 in a short time.

  In addition, after the back electrode 12 and the photoelectric conversion layer 14 are sequentially formed on the substrate 11, before the buffer layer 15 is formed, the dopant-containing material 13 is brought into contact with the surface of the photoelectric conversion layer 14, and heat treatment is performed. Next, after separating the dopant-containing material 13 from the photoelectric conversion layer 14, the buffer layer 15 and the transparent electrode 16 may be sequentially formed on the photoelectric conversion layer 14.

Example 1
Mo was used as a sputtering target, and a Mo thin film having a thickness of 500 nm was formed on an alkali-free glass substrate by a magnetron sputtering method in a state where the substrate and the sputtering target were arranged in parallel. The substrate temperature during deposition of the Mo thin film is room temperature, the distance between the sputtering target and the substrate is 10 cm, the flow rate of argon gas supplied to the sputtering apparatus is 50 sccm, the pressure in the sputtering apparatus is 0.4 Pa, and the deposition rate is 7.7 nm / It was set to min. An RF power source was used to power on the sputtering target, and 300 W power was applied. Na and K were not detected when the Mo thin film formed was subjected to elemental analysis by secondary ion mass spectrometry (SIMS).
Next, a Mo plate containing 5 at% Na (hereinafter referred to as “MoNa plate”) was brought into contact with the Mo film-forming surface of the Mo thin film, and was pressed with a pressing force of 9.8 kPa. And while maintaining this state, it put into the vacuum heating apparatus and heated the Mo film | membrane to 400 degreeC for 30 minutes using the heater for a substrate heating with which the apparatus was equipped. After the heat treatment, it was taken out from the vacuum heating device, and the MoNa plate was separated from the Mo thin film. When the Mo thin film separated from the MoNa plate was subjected to elemental analysis by secondary ion mass spectrometry (SIMS), it was confirmed that it contained Na.
Next, an In / (Cu, Ga) laminated film is formed on the surface of the Mo thin film by sputtering, and the In / (Cu, Ga) laminated film is annealed at 550 ° C. in an H ₂ Se gas atmosphere. Then, selenization was performed, and a photoelectric conversion layer made of Cu (In, Ga) Se ₂ was formed to a thickness of 2.0 μm. Elemental analysis of this photoelectric conversion layer by secondary ion mass spectrometry (SIMS) confirmed that it contained Na.
Next, a CdS film having a thickness of 30 to 50 nm was formed on the photoelectric conversion layer by a solution growth method to form a buffer layer.
Then, a ZnO layer doped with gallium was formed to a thickness of 300 nm on the buffer layer by a sputtering method, a transparent electrode was formed, and a CIGS solar cell was manufactured.

(Example 2)
On an alkali-free glass substrate, a Mo thin film having a thickness of 500 nm was formed under the same conditions as in Example 1.
Next, heat treatment was performed by bringing a Mo plate containing 5 at% K (hereinafter referred to as “MoK plate”) into contact with the Mo film-forming surface of the Mo thin film under the same conditions as in Example 1. After the heat treatment, the MoK plate was separated from the Mo thin film. Elemental analysis of the Mo thin film separated from the MoK plate by secondary ion mass spectrometry (SIMS) confirmed that it contained K.
Next, a photoelectric conversion layer, a buffer layer, and a transparent electrode were formed on the Mo thin film under the same conditions as in Example 1 to manufacture a CIGS solar cell.

(Example 3)
On an alkali-free glass substrate, a Mo thin film having a thickness of 500 nm was formed under the same conditions as in Example 1.
Next, the soda-lime glass plate was subjected to heat treatment under the same conditions as in Example 1 by bringing it into contact with the Mo film-forming surface of the Mo thin film. After the heat treatment, the soda lime glass plate was separated from the Mo thin film. Elemental analysis of the Mo thin film separated from the soda lime glass plate by secondary ion mass spectrometry (SIMS) confirmed that it contained Na.
Next, a photoelectric conversion layer, a buffer layer, and a transparent electrode were formed on the Mo thin film under the same conditions as in Example 1 to manufacture a CIGS solar cell.

Example 4
On an alkali-free glass substrate, a Mo thin film having a thickness of 500 nm was formed under the same conditions as in Example 1. A photoelectric conversion layer was formed on the Mo thin film under the same conditions as in Example 1. When this photoelectric conversion layer was subjected to elemental analysis by secondary ion mass spectrometry (SIMS), Na was not detected.
Next, the MoNa plate was brought into contact with the photoelectric conversion layer and pressed with a pressing force of 9.8 kPa. And while maintaining this state, it put into the vacuum heating apparatus and heated the photoelectric converting layer to 400 degreeC for 30 minutes using the heater for substrate heating with which the apparatus was equipped. After the heat treatment, it was taken out from the vacuum heating device, and the MoNa plate was separated from the photoelectric conversion layer. When the elemental analysis of the photoelectric conversion layer from which the MoNa plate was separated was performed by secondary ion mass spectrometry (SIMS), it was confirmed that Na was contained.
Next, a CIGS solar cell was manufactured by forming a buffer layer and a transparent electrode on the photoelectric conversion layer under the same conditions as in Example 1.

(Example 5)
On an alkali-free glass substrate, a Mo thin film having a thickness of 500 nm was formed under the same conditions as in Example 1.
Next, heat treatment was performed by bringing the MoNa plate into contact with the Mo film-forming surface of the Mo thin film under the same conditions as in Example 1. After the heat treatment, the MoNa plate was separated from the Mo thin film.
Next, a photoelectric conversion layer was formed on the Mo thin film under the same conditions as in Example 1.
Next, the MoNa plate was brought into contact with the photoelectric conversion layer under the same conditions as in Example 4, and heat treatment was performed. After the heat treatment, the MoNa plate was separated from the photoelectric conversion layer. Elemental analysis of the photoelectric conversion layer separated from the MoNa plate by secondary ion mass spectrometry (SIMS) confirmed that it contained Na.
Next, a CIGS solar cell was manufactured by forming a buffer layer and a transparent electrode on the photoelectric conversion layer under the same conditions as in Example 1.

(Comparative Example 1)
On an alkali-free glass substrate, a Mo thin film having a thickness of 500 nm was formed under the same conditions as in Example 1. On this Mo thin film, the photoelectric conversion layer, the buffer layer, and the transparent electrode were formed on the same conditions as Example 1, and the CIGS type solar cell was manufactured.

  The CIGS solar cells of Examples 1 to 5 and Comparative Example 1 were irradiated with simulated sunlight (AM1.5) to examine the conversion efficiency. The results are summarized in Table 1.

  As shown in Table 1, Examples 1 to 5 had higher conversion efficiency than Comparative Example 1. This reason is considered to be due to the effect of adding Na to the photoelectric conversion layer.

  Moreover, although the conversion efficiency of Example 1 was higher than Example 2, it is thought that this is because Na is more effective in improving the conversion efficiency of the CIGS solar cell than K. .

  Moreover, although Example 5 had the highest conversion efficiency, since the MoNa plate was brought into contact with both the Mo thin film and the photoelectric conversion layer, it is considered that a large amount of Na was added to the photoelectric conversion layer. .

1: first material 2: second material 3: third material 5: dopant 11: substrate 12: back electrode 13: dopant-containing material 14: photoelectric conversion layer 15: buffer layer 16: transparent electrode

Claims (7)

  A first material selected from a semiconductor and an electrode is brought into contact with a second material containing a dopant, and heat treatment is performed in a state in which both materials are in contact with each other, so that the dopant contained in the second material is transferred to the first material. Then, the second material is separated from the first material, and then the dopant diffusion method.   The dopant diffusion method according to claim 1, wherein after the second material is separated from the first material, a third material selected from a semiconductor and an electrode is stacked on the first material, and heat treatment is performed. .   The dopant diffusion method according to claim 2, wherein the first material is an electrode and the third material is a semiconductor.   The first material is an electrode in which a metal layer containing Mo is arranged on the third material side, and the third material contains at least Cu, In and / or Ga, and Se and / or S. The dopant diffusion method according to claim 3, wherein the semiconductor is a semiconductor that includes at least Cu, Zn, Sn, Se, and / or S. 5.   The dopant diffusion method according to claim 1, wherein the dopant is an alkali metal. An electronic device comprising: a substrate; a first electrode stacked on the substrate; a semiconductor layer; and a second electrode, wherein the semiconductor layer is disposed between the first electrode and the second electrode. In the manufacturing method,
A material containing a dopant is brought into contact with the first electrode, heat treatment is performed in a state where both are brought into contact, and the dopant contained in the material is transferred to the first electrode, and then the material is transferred from the first electrode to the material. Then, the semiconductor layer is formed on the first electrode, and heat treatment is performed during or after the formation of the semiconductor layer. The first electrode is an electrode in which a metal layer containing Mo is disposed on the semiconductor layer side,
The semiconductor layer is formed of a semiconductor containing at least Cu, In and / or Ga, Se and / or S, or a semiconductor containing at least Cu, Zn, Sn, Se and / or S. The method of manufacturing an electronic device according to claim 6.