WO2006049003A1

WO2006049003A1 - Process for producing thin-film photoelectric converter

Info

Publication number: WO2006049003A1
Application number: PCT/JP2005/018930
Authority: WO
Inventors: Toru Sawada; Kenji Yamamoto
Original assignee: Kaneka Corporation
Priority date: 2004-11-04
Filing date: 2005-10-14
Publication date: 2006-05-11
Also published as: JPWO2006049003A1

Abstract

A process for producing at low cost a thin-film photoelectric converter of high efficiency that even when use is made of a transparent conductive film consisting of zinc oxide with low thermal stability, avoids any increase of resistivity thereof. There is provided a process for producing a thin-film photoelectric converter, the thin-film photoelectric converter composed of a translucent substrate and, sequentially superimposed on one major surface thereof, a transparent conductive film composed mainly of zinc oxide, a photoelectric conversion unit of one or more units including at least a first photoelectric conversion unit and a backside electrode layer, which process is characterized by including the step of providing the first photoelectric conversion unit directly superimposed on the transparent conductive film, the first photoelectric conversion unit comprising a first conductive semiconductor layer of silicon base, wherein the first conductive semiconductor layer of silicon base is formed on the transparent conductive film maintained at ≤ 170°C; and the step of after formation of the backside electrode layer, effecting heating under atmospheric pressure at ≥ 170°C.

Description

Specification

Method for manufacturing thin film photoelectric conversion device

Technical field

The present invention relates to a method for manufacturing a thin film photoelectric conversion device in which a silicon-based one-conductivity type semiconductor layer is directly formed on a transparent conductive film containing zinc oxide as a main component.

Background art

In recent years, thin film photoelectric conversion devices represented by thin film solar cells have also diversified, and in addition to conventional amorphous thin film photoelectric conversion devices, crystalline thin film photoelectric conversion devices have also been developed, and hybrid thin film photoelectric conversions in which these are stacked. The device has also been put into practical use. Such a thin film photoelectric conversion device generally includes a transparent conductive film, one or more photoelectric conversion units, and a back electrode layer, which are sequentially stacked on a light-transmitting substrate.

[0003] One photoelectric conversion unit includes a photoelectric conversion layer sandwiched between one conductivity type semiconductor layer and another conductivity type semiconductor layer. As the one-conductivity-type semiconductor layer, a silicon-based one-conductivity-type semiconductor layer is often used. The photoelectric conversion layer is usually formed as an i-type layer. Here, for example, the one-conductivity-type semiconductor layer is a p-type layer, and in this case, the other-conductivity-type semiconductor layer is an n-type layer, and vice versa.

[0004] The photoelectric conversion layer is not limited to an intrinsic semiconductor layer (i-type layer), but is doped in a small amount to p-type or n-type as long as loss of light absorbed by the doped impurity (dopant) does not become a problem. It may be a layer. The photoelectric conversion layer is preferably thicker for light absorption, but if it is thicker than necessary, the cost and time for film formation will increase.

On the other hand, the p-type and n-type conductive semiconductor layers serve to generate an internal electric field in the photoelectric conversion unit, and are one of the important characteristics of the thin film photoelectric conversion device depending on the magnitude of the internal electric field. The value of open circuit voltage (Voc) is affected. However, these conductive semiconductor layers are inactive layers that do not directly contribute to photoelectric conversion, and light absorbed by impurities doped in the conductive semiconductor layer is a loss that does not contribute to power generation. Therefore, it is preferable to keep the p-type and n-type conductive semiconductor layers as small as possible as long as they are within a range in which a sufficient internal electric field can be generated. The thickness of the conductive semiconductor layer is generally about 20 nm It is as follows.

[0006] Here, the photoelectric conversion unit or the thin film photoelectric conversion device has a photoelectric conversion layer that occupies the main part regardless of whether the p-type and n-type conductive semiconductor layers included therein are amorphous or crystalline. Amorphous materials are referred to as amorphous units or amorphous thin film photoelectric conversion devices, and those with a crystalline photoelectric conversion layer are referred to as crystalline units or crystalline thin film photoelectric conversion devices.

[0007] As a method for improving the conversion efficiency of a thin film photoelectric conversion device, there is a method of stacking two or more photoelectric conversion units into a tandem type. In this method, a front unit including a photoelectric conversion layer having a large band gap is disposed on the light incident side of the thin film photoelectric conversion device, and a rear unit including a photoelectric conversion layer having a small band gap is sequentially disposed behind the front unit. Thus, photoelectric conversion can be performed over a wide wavelength range of incident light, thereby improving the conversion efficiency of the entire photoelectric conversion device. Among such tandem photoelectric conversion devices, those in which an amorphous photoelectric conversion unit and a crystalline photoelectric conversion unit are stacked are called hybrid thin film photoelectric conversion devices.

[0008] For example, the wavelength of light that can be photoelectrically converted by an amorphous silicon photoelectric conversion unit using i-type amorphous silicon as a photoelectric conversion layer is about 800 nm on the long wavelength side. The crystalline silicon photoelectric conversion unit as the photoelectric conversion layer can photoelectrically convert light up to about 1150 nm longer than that. However, an amorphous silicon photoelectric conversion layer with a large light absorption coefficient may have a thickness of about 0.3 μm or less for light absorption, but a crystalline silicon photoelectric conversion layer with a small light absorption coefficient is long. In order to sufficiently absorb light of a wavelength, it is preferable to have a thickness of about 1.5 to 3 μΐη. That is, the crystalline photoelectric conversion layer is usually desired to have a thickness of about 5 to 10 times that of the amorphous photoelectric conversion layer.

[0009] The translucent substrate usually allows sufficient light to reach the transparent conductive film and the photoelectric conversion unit formed thereon, and protects the photoelectric conversion device from impact and outside air when installed outdoors. Play a role. For this reason, for example, when a crystalline photoelectric conversion unit having crystalline silicon as a photoelectric conversion layer is formed on a light-transmitting substrate, the light-transmitting substrate is used for light having a wavelength of about 350 to 1150 ηm. It is desirable to have sufficient light transmittance. Translucent As the conductive substrate, it is desirable to use a material excellent in impact resistance and weather resistance.

[0010] The transparent conductive film transmits the light incident through the translucent substrate to the photoelectric conversion unit side without losing as much as possible, and efficiently takes out the photocurrent generated in the photoelectric conversion unit to the outside. For this reason, it is desirable to have both high transparency and low sheet resistance. When the sheet resistance increases, the series resistance of the photoelectric conversion device increases, and as a result, the fill factor (FF) decreases.

The thin film photoelectric conversion device can make the photoelectric conversion layer thinner than conventional photoelectric conversion devices using Balta single crystals or polycrystals, but on the other hand, the light absorption is the thickness of the photoelectric conversion layer. There is a problem that it is limited by this. Therefore, in order to use light incident on the photoelectric conversion unit including the photoelectric conversion layer more effectively, after forming fine irregularities on the surface of the transparent conductive film in contact with the photoelectric conversion unit and scattering the light at the interface, A device has been devised to extend the optical path length by making it enter the photoelectric conversion unit and to increase the amount of light absorption in the photoelectric conversion layer. This technology is called “optical confinement” and has become an important elemental technology for the practical application of thin film photoelectric conversion devices with high photoelectric conversion efficiency.

[0012] The height difference of the irregularities is generally about 0 · 05 μm to 0.3 μm.

There is a haze ratio as an index representing the degree of unevenness of the transparent conductive film. This is equivalent to the light that is transmitted when the light from a specific light source is incident on a transparent substrate with a transparent conductive film divided by the scattered component whose optical path is bent and divided by all components. Measured using a C light source containing light. Generally, the haze ratio increases as the height difference between the projections and depressions increases, or as the spacing between the projections and depressions of the projections and projections increases, and the light incident on the photoelectric conversion unit is effectively confined. The effect is excellent.

[0014] Therefore, whether the amorphous silicon single-layer thin film photoelectric conversion device or the above-described hybrid thin film photoelectric conversion device, the transparency of the transparent conductive film is improved, the haze ratio is increased, and the sheet resistance is increased. If it can be kept low, a high short-circuit current density (tisc) can be maintained even if the thickness of the photoelectric conversion layer is reduced, and a high fill factor (FF) can be obtained, so that the performance of the thin film photoelectric conversion device can be improved. Can be improved, and also leads to lower manufacturing costs

[0015] Tin oxide has been generally used as a material for the transparent conductive film since ancient times, but it is 500 ° C. Since the above thermal CVD method is used, the material used for the light-transmitting substrate is limited, and by adjusting the formation conditions, the distance between the convex and concave portions is increased to increase the haze ratio. The problem is that it will be difficult to maintain Voc. Furthermore, since the light absorption loss of the material itself is large, if the sheet resistance is kept at a value of about 10 Ω, which is normally used, the thin film amorphous silicon is an important absorption region of crystalline silicon. Absorption loss of ~ 800nm is negligible.

[0016] To deal with such problems, in recent years, a method using zinc oxide formed by a thermal CVD method at about 200 ° C for a transparent conductive film has attracted attention. Since the transparent conductive film made of zinc oxide is formed at a low temperature, there are advantages in that the choice of materials that can be used for the light-transmitting substrate is widened, and that Voc can be maintained even if the haze ratio is increased. This is thought to be due to the difference in surface shape from the transparent conductive film made of tin oxide. In addition, there is an advantage that Jsc of a thin film photoelectric conversion device in which the light absorption loss of the material itself is small can be increased.

[0017] Non-Patent Document 1 describes the use of a film having a zinc oxide force formed by a CVD method as a transparent conductive film of a thin film photoelectric conversion device. Specifically, a transparent conductive film made of zinc oxide with boron added is formed at 170-200 ° C to form a transparent conductive film having a sheet resistance value of about 4 Ω / mouth, and then an amorphous film is formed thereon. A silicon layer is formed by high-frequency plasma CVD to obtain an amorphous silicon single-pole photoelectric conversion device. Here, when the thickness of the i-type amorphous silicon layer is 0.35 μΐη, FF is 0.72 to 0.73, Jsc is 17.5 mA / cm ² , and conversion efficiency is 2%. Has been.

Non-Patent Document 1: J. Meier et al., "Efficiency enhancement of amorphous silicon p_i_n solar cells by LP-CVD ZnO", Proc. Of 28th IEEE Photovoltaic Specialists Conferenc e, Anchorage, 2000, pp.746-749

Disclosure of the invention

Problems to be solved by the invention

In view of the situation as described above, the present invention relates to a thin film photoelectric conversion device in which a silicon-based one-conductivity type semiconductor layer is directly formed on a transparent conductive film containing zinc oxide as a main component. It is an object of the present invention to obtain a method for manufacturing a thin film photoelectric conversion device capable of improving the photoelectric conversion characteristics. In particular, when a transparent conductive film having low heat resistance and zinc oxide strength formed by thermal CVD is used, a photoelectric conversion unit is formed on the transparent conductive film without changing its resistivity. Thus, the present invention relates to a method of manufacturing a thin film photoelectric conversion device that can sufficiently exhibit the potential of the transparent conductive film.

Means for solving the problem

[0020] A method for producing a thin film photoelectric conversion device according to the present invention includes a transparent conductive film mainly composed of zinc oxide and at least a first photoelectric conversion unit in order on one main surface of a translucent substrate. A method of manufacturing a thin film photoelectric conversion device comprising the above photoelectric conversion unit and a back electrode layer, wherein the photoelectric conversion unit comprises, in order from the translucent substrate side, a one-conductive semiconductor layer, a photoelectric conversion layer, and The one-conductivity-type semiconductor layer comprising another conductive-type semiconductor layer, wherein the first photoelectric conversion unit is directly formed on the transparent conductive film, and which constitutes the first photoelectric-conversion unit Is silicon-based, and the step of forming the silicon-based one-conductivity type semiconductor layer on the transparent conductive film maintained at a temperature of 170 ° C. or lower, and the atmospheric pressure of 170 ° C. or higher after the formation of the back electrode layer Including the step of heating at A method of manufacturing a thin film photoelectric conversion device. The formation temperature of the silicon-based one-conductivity-type semiconductor layer formed on the transparent conductive film is set to 170 ° C or lower to prevent the resistance of the transparent conductive film from being increased by heating. In order to increase the activation rate of the dopant in the semiconductor layer, and to ensure that each junction interface between the transparent conductive film and the silicon-based one-conductivity-type semiconductor layer and the other conductive-type semiconductor layer and the back-electrode layer is in ohmic contact, the back electrode After the layer formation, heating is performed under atmospheric pressure at a temperature equal to or higher than the formation temperature of the silicon-based single conductivity type semiconductor layer. By these actions, a thin film photoelectric conversion device with improved photoelectric conversion characteristics can be manufactured.

In addition, the method for manufacturing a thin film photoelectric conversion device according to the present invention further includes a step of forming the transparent conductive film by a CVD method using a source gas containing at least zinc, boron, and oxygen as elements. preferable. This is because the effects of the present invention are particularly effective for zinc oxide formed by CVD using a source gas containing zinc, boron, and oxygen as elements.

The invention's effect According to the present invention, even when a transparent conductive film having low heat resistance and zinc oxide strength is used, the resistance change of the transparent conductive film can be suppressed, and the series resistance of the photoelectric conversion device can be kept small. . As a result, a highly efficient thin film photoelectric conversion device can be provided at a low cost with a simple process.

Brief Description of Drawings

FIG. 1 is a schematic cross-sectional view of a hybrid thin film photoelectric conversion device.

FIG. 2 is a schematic cross-sectional view of an amorphous silicon single photoelectric conversion device.

FIG. 3 is a depth profile of hydrogen, carbon, oxygen and nitrogen concentrations of an amorphous silicon single photoelectric conversion device fabricated under the conditions of Example 1.

FIG. 4 is a depth profile of hydrogen, carbon, oxygen and nitrogen concentrations of an amorphous silicon single photoelectric conversion device fabricated under the conditions of Comparative Example 1.

[Fig.5] Hydrogen, carbon of amorphous silicon single photoelectric conversion device fabricated under the conditions of reference example

2 is a depth profile of oxygen and nitrogen concentrations.

FIG. 6 is a schematic cross-sectional view of an integrated hybrid thin film photoelectric conversion device.

Explanation of symbols

1 Translucent substrate

2 Transparent conductive film

3 Amorphous photoelectric conversion unit

3p amorphous p-type silicon carbide layer

3i Non-doped amorphous i-type silicon photoelectric conversion layer

3n _n- type silicon layer

4 Crystalline photoelectric conversion unit

4p P-type crystalline silicon layer

4i Crystalline i-type silicon photoelectric conversion layer

4n n-type crystalline silicon layer

5 Mineral electrode layer

5t transparent reflective layer

2a Transparent electrode layer separation groove 4a Connection groove

5a Back electrode layer separation groove

BEST MODE FOR CARRYING OUT THE INVENTION

[0025] The present inventors actually formed a thin film photoelectric conversion device using a zinc oxide-powered film formed by a CVD method as the transparent conductive film of the thin film photoelectric conversion device. As a result, the inventors have found that there are the following problems and arrived at the present invention.

[0026] First, it has been found that a transparent conductive film using zinc oxide formed by thermal CVD has a problem of low heat resistance. Specifically, if the transparent conductive film is formed and left in the atmosphere for several months, the sheet resistance of the film increases by an order of magnitude or more. In addition, when the transparent conductive film is annealed in the atmosphere at a temperature of about 200 ° C., the sheet resistance of the film similarly increases. In addition, when a thin film photoelectric conversion device is formed on a transparent conductive film, the resistance of the transparent conductive film similarly increases and the series resistance of the photoelectric conversion device increases.

[0027] In order to solve such problems, the present inventors diligently studied the optimum conditions for producing a photoelectric conversion device. As a result, a silicon-based one-conductivity-type semiconductor layer formed on the transparent conductive film is formed at a temperature of 170 ° C. or lower, and then a photoelectric conversion layer, another conductivity-type semiconductor layer, and a back electrode layer are formed. It has been found that the resistance of the transparent conductive film can be prevented from being increased by heating at atmospheric temperature or higher under atmospheric pressure.

[0028] The present invention can be applied to a transparent conductive film made of zinc oxide and formed by a shift method such as a CVD method, a sputtering method, or a vapor deposition method. In particular, zinc, boron, and oxygen are used as elements. It is effective for zinc oxide formed by the CVD method using source gas containing

[0029] In the present invention, the high resistance of the transparent conductive film made of zinc oxide is prevented by forming the silicon-based one-conductivity-type semiconductor layer directly formed on the transparent conductive film at a temperature of 170 ° C or lower. Can do. Although this mechanism is not clear, the conductivity of the zinc oxide film is largely related to the oxygen defect structure in the film, and when this is heated in an oxygen atmosphere, it is slightly in the atmosphere even under reduced pressure. It is considered that oxygen contained in the film is taken into the film and oxygen deficiency that becomes an electron flow path is reduced, and the resistivity is increased. On the other hand, if the silicon-based one-conductivity-type semiconductor layer is formed at a temperature of 170 ° C or lower and the transparent conductive film is covered, oxygen atoms are taken into the transparent conductive film even after a temperature higher than the above temperature. This That's not possible. This is considered to prevent the high resistance of the transparent conductive film.

[0030] On the other hand, at a formation temperature of 170 ° C or lower, the activation rate of the dopant in the one-conductivity-type semiconductor layer mainly composed of silicon may not be sufficiently increased. In some cases, the junction interface between the semiconductor layer, the other conductivity type semiconductor layer, and the back electrode layer does not form ohmic contact. This problem is determined by performing a process of heating the photoelectric conversion device at a temperature of 170 ° C. or higher and atmospheric pressure after the photoelectric conversion device is formed, for example, after the back electrode layer is formed.

[0031] The gas used in the heating atmosphere is preferably air, nitrogen, a mixture of nitrogen and oxygen, or the like. Moreover, the same effect is recognized not only at atmospheric pressure but also under some reduced pressure or increased pressure. Specifically, it has an effect in a range of at least 0.5 to: 1.5 atm.

Hereinafter, a thin film photoelectric conversion device as an embodiment of the present invention will be described with reference to FIG. 1 and FIG.

A transparent conductive film 2 is formed on the translucent substrate 1. As the translucent substrate 1, a plate-like member made of glass, transparent resin or the like or a sheet-like member is used. When glass is used as the translucent substrate 1, it is desirable that the total iron oxide converted to FeO contained in the glass be as small as possible in order to suppress the decrease in visible transmittance due to light irradiation. Specifically, it is desirable to be 0.02% by weight or less.

[0034] As the transparent conductive film 2, zinc oxide is used. The transparent conductive film 2 is preferably formed by a method such as CVD, sputtering, or vapor deposition. In particular, the transparent conductive film 2 is preferably formed by a CVD method having a formation temperature of about 200 ° C. In addition, it is desirable to use boron as a doping material. The transparent conductive film 2 has the effect of increasing the scattering of incident light by producing fine irregularities on the surface by devising the formation conditions. The height difference of the unevenness is about 0.05 to 0. The sheet resistance is set to about 5 to 20 Ω Z port.

[0035] One or more photoelectric conversion units are formed on the transparent conductive film 2 mainly composed of zinc oxide. The photoelectric conversion unit may be an amorphous photoelectric conversion unit or a single unit of a crystalline photoelectric conversion unit, or a hybrid type in which these are laminated. Further, three or more units of these may be laminated. In addition, materials used for the photoelectric conversion unit include silicon, Silicon alloys such as silicon carbide and silicon germanium, and compound materials such as copper-indium-selenium and gallium-arsenic are also preferably used.

For example, when a single unit of an amorphous photoelectric conversion unit is used as the photoelectric conversion unit and silicon is used as the material, the structure is as shown in FIG. That is, an amorphous photoelectric conversion unit comprising an amorphous p-type silicon carbide layer 3p, a non-doped amorphous i-type silicon photoelectric conversion layer 3i, and an n-type silicon layer 3n on the transparent conductive film 2 as a one-conductivity type semiconductor layer. 3 is formed. The amorphous p-type silicon carbide layer 3p is formed at a substrate temperature of 170 ° C. or less in order to prevent the transparent conductive film 2 from being increased in resistance by heating.

On the other hand, for example, in a hybrid semiconductor thin film photoelectric conversion device, a crystalline photoelectric conversion unit 4 is formed on an amorphous photoelectric conversion unit 3 as shown in FIG. The crystalline photoelectric conversion unit 4 includes a crystalline p-type silicon layer 4p, a crystalline i-type silicon photoelectric conversion layer 4i, and a crystalline n-type silicon layer 4n. A high-frequency plasma CVD method is suitable for forming the amorphous photoelectric conversion unit 3 and the crystalline photoelectric conversion unit 4. The formation conditions of the photoelectric conversion unit are: substrate temperature 100 to 250 ° C (however, amorphous p-type silicon carbide layer 3p is 170 ° C or less), pressure 30 to: 1500Pa, high frequency power density 0 · 01 to 0.5 W / cm ² is preferably used. The source gas used to form the photoelectric conversion unit is SiH

A silicon-containing gas such as SiH or a mixture of these gases and hydrogen is used. B H or PH is preferably used as the dopant gas for forming the p-type or n-type layer in the photoelectric conversion unit.

A back electrode layer 5 is formed on the n-type silicon layer 3n in FIG. 2 or the n-type silicon layer 4n in FIG. For the back electrode layer 5, Ag, A or an alloy thereof is preferably used. Between the back electrode layer 5 and the n-type silicon layer 4n, a transparent reflective layer 5t may be inserted in order to prevent diffusion of metal from the back electrode layer 5 to the n-type silicon layer 4n. For the transparent reflective layer 5t, a metal oxide having high resistance and excellent transparency such as ZnO or ITO is used. In forming the transparent reflective layer 5t and the back electrode layer 5, methods such as sputtering and vapor deposition are preferably used.

[0039] After the back electrode layer 5 is formed, as described above, the silicon-based one-conductivity-type semiconductor layer, for example, the amorphous P-type silicon carbide layer 3p is formed under atmospheric pressure at an atmospheric temperature equal to or higher than the formation temperature. Example of manufacturing method of thin film photoelectric conversion device of the present invention by heating photoelectric conversion device

[0040] Hereinafter, Examples 1 and 2 of the method for manufacturing a thin film photoelectric conversion device according to the present invention will be described with reference to FIG.

Referring to FIG. 3, the description will be made in comparison with Comparative Examples 1 to 4.

[Example 1]

FIG. 2 is a cross-sectional view schematically showing the amorphous silicon single photoelectric conversion device manufactured in Example 1.

[0042] First, a transparent conductive film 2 having a fine concavo-convex structure on a surface made of zinc oxide was formed on one main surface of a light-transmitting substrate 1 made of white plate glass having a thickness of 0.7 mm by a thermal CVD method. As the formation conditions, the surface temperature of the substrate 1 was set to 160 to 180 ° C., the pressure was lOOPa, and jetyl zinc, water, BH, argon, and hydrogen were used as source gases. The obtained transparent conductive film 2 had a thickness of 1 · 5 μΐη, a haze ratio of 22%, and a sheet resistance of 10 Ω / mouth.

Next, in order to form the amorphous photoelectric conversion unit 3 as the first photoelectric conversion unit, the transparent substrate 1 on which the transparent conductive film 2 is formed is introduced into a high-frequency plasma CVD apparatus, After heating so that the surface temperature of the plate 1 becomes 170 ° C, an amorphous p-type silicon carbide (p-type a_SiC) layer (not shown) having a thickness of 20 A as a silicon-based one-conductivity semiconductor layer, A microcrystalline p-type silicon layer (not shown) with a thickness of 50 A and a p-type a_SiC layer 3p with a thickness of 150 A were sequentially formed. Subsequently, after the surface temperature of the substrate 1 is heated to a predetermined temperature, a non-doped amorphous i-type silicon photoelectric conversion layer 3i having a thickness of 3000 A is formed as a photoelectric conversion layer, and a thickness of 150 A is provided as another conductive type semiconductor layer. The n-type silicon layer 3n was sequentially laminated.

At this time, the formation conditions of the p-type a_SiC layer 3p were as follows: the pressure was 150 to 400 Pa, the high frequency power density was 0.02 to 0.05 WZcm ² , and SiH: hydrogen: hydrogen was diluted to 0.1%. BH: CH gas ratio is 1: 30: 10: 1.6, and BH diluted to 0.1% with hydrogen while maintaining the discharge when the layer thickness reaches 80A The supply of CH was stopped, and instead, the gas ratio of hydrogen to SiH was increased from 30 to 40, and the remaining 70 A was formed.

Next, a transparent reflective layer 5t made of ZnO having a thickness of 900A and a back electrode layer 5 made of Ag having a thickness of 2000A were formed as a back electrode layer by a DC sputtering method. In addition, YAG second harmonic By irradiating a wave pulse laser from the translucent substrate 1 side, only the transparent conductive film 2 is left, and the amorphous photoelectric conversion unit 3, the transparent reflective layer 5t, and the back electrode layer 5 are lines having a width of 50 / m. As a result, a 1 cm square island-shaped photoelectric conversion device region was formed.

[0046] Thereafter, the photoelectric conversion device of Example 1 was manufactured by performing heat treatment in the atmosphere at an atmospheric temperature of 170 ° C for 90 minutes.

[0047] amorphous silicon single Honoré photovoltaic device manufactured in Example 1, the spectral distribution AMI. 5, a pseudo solar light energy density lOOmW / cm ^2, the temperature of the measurement atmosphere and the photoelectric conversion equipment is 25 ± Irradiation was performed at 1 ° C, and the output characteristics of the thin film photoelectric conversion device were measured. Table 1 shows the measurement results of Voc, Jsc, FF, conversion efficiency (Eff.), And series resistance (Rs). When the pressure during the previous heat treatment was changed in the range of 0.5 to 1.5 atm, the obtained photoelectric conversion device characteristics were the same.

[0048] Table 1 is a table comparing the photoelectric conversion characteristics of amorphous silicon single photoelectric conversion devices manufactured under the conditions of Example 1 and Comparative Examples 1 and 2 and Reference Examples described later.

[0049] [Table 1]

[0050] (Comparative Example 1)

In Comparative Example 1, almost the same process as in Example 1 was performed, but the point power was different from that in Example 1 in which heat treatment was performed in the atmosphere at an atmospheric temperature of 150 ° C. after the back electrode layer 5 was formed. Table 1 shows the measurement results.

[0051] (Comparative Example 2)

In Comparative Example 1, almost the same process as in Example 1 was performed, but the formation temperature of the p-type a-SiC layer 3p was 185 ° C, which was different from Example 1. Table 1 shows the measurement results.

[0052] From the comparison between Example 1 and Comparative Example 1 in Table 1, it was found that the atmospheric temperature for heat treatment in the atmosphere was 150 ° C force, and 170 ° C, the same as the formation temperature of the p-type a_SiC layer. Improved by 0.3% I understand that. This is thought to be due to the improved dopant activation rate of the p-type a-SiC layer and the improved ohmic contact between the conductive semiconductor layer and the electrode. In addition, in Example 1, the sheet resistance of the transparent conductive film was 10 Ω / mouth, which was relatively high and the value was close to 0.74 FF. Compared to FF in Patent Document 1, it is a large value.

[0053] On the other hand, from the comparison between Example 1 and Comparative Example 2, when the formation temperature of the p-type a_SiC layer is 185 ° C, the transparent conductive film increases in resistance, so that the series resistance (Rs) of the photoelectric conversion device is increased. Increases, FF decreases and the difference in Eff. Reaches 0.8%.

[0054] (Reference example)

In the reference example, substantially the same process as in Comparative Example 1 was performed, but after forming the transparent electrode film 2, the translucent substrate 1 was once heat-treated in the atmosphere at an atmospheric temperature of 200 ° C. for 90 minutes, It was different from Comparative Example 1 in that it was introduced into the high-frequency plasma CVD apparatus. Table 1 shows the measurement results. In this reference example, the resistivity of the zinc oxide film increased due to the influence of heat treatment at 200 ° C in the atmosphere, or the oxygen atoms taken into the zinc oxide film by this treatment are converted into photoelectric conversion units, In particular, the force, especially the series resistance Rs, increased due to diffusion in the p-type layer, resulting in a lower photoelectric conversion characteristic Eff. Than Example 1 and each comparative example.

[0055] In addition, for each of the amorphous silicon single photoelectric conversion devices manufactured under the conditions of Example 1, Comparative Example 1, and Reference Example, the ion is directed from the back electrode layer 5 side toward the translucent substrate 1 side. The depth profiles of hydrogen, carbon, oxygen and nitrogen concentrations were measured by SIMS while sputtering. The measurement results of Example 1, Comparative Example 1, and Reference Example are shown in FIG. 3, FIG. 4, and FIG. 5, respectively. In each figure, the horizontal axis 0.6 μ ΐη corresponds to the interface between the _a- SiC that is the p-type layer and the a_S layer that is the i-type layer of the photoelectric conversion layer. Is an average value rather than a plane, but the oxygen amount at that point is about 10 ²¹ atoms / cc in Example 1 and Comparative Example 1 as shown by the horizontal line in each figure, whereas in the reference example The reference example was several times higher at about 10 ²² atoms Zcc, and the results supporting the above estimation were obtained.

[0056] (Example 2)

FIG. 6 schematically shows the integrated hybrid thin film photoelectric conversion device fabricated in Example 2. It is sectional drawing.

[0057] First, a transparent conductive film 2 having a fine concavo-convex structure on a surface made of zinc oxide is formed on one main surface of a translucent substrate 1 made of 910 mm x 455 mm x 4 mm thick white glass by a thermal CVD method. did. As formation conditions, the surface temperature of the translucent substrate 1 was set to 150 to: 180 ° C., pressure lOOPa, and jetyl zinc, water, BH, argon, and hydrogen were used as source gases. The obtained transparent conductive film 2 had a thickness of 1.7 × m, a haze ratio of 25%, and a sheet resistance of 9.5 Ω / Π. Next, a transparent electrode layer separation groove 2a having a width of 50 μm is formed by irradiating the transparent substrate 1 with a YAG fundamental pulse laser to divide the transparent electrode layer 2 into a plurality of strip patterns. Then, ultrasonic cleaning and drying were performed.

Next, in order to form the amorphous photoelectric conversion unit 3 as the first photoelectric conversion unit, the translucent substrate 1 on which the transparent conductive film 2 is formed is introduced into a high-frequency plasma CVD apparatus, and the substrate After heating so that the surface temperature of 1 becomes 165 ° C, an amorphous p-type silicon carbide (p-type a-SiC) layer (not shown) having a thickness of 20 A is formed as a silicon-based one-conductivity-type semiconductor layer. ), A microcrystalline p-type silicon layer (not shown) having a thickness of 50 A, and a p-type a-SiC layer 3p having a thickness of 150 A were sequentially formed. Subsequently, after the surface temperature of the substrate 1 is heated to a predetermined temperature, a non-doped amorphous i-type silicon photoelectric conversion layer 3i having a thickness of 3000 A is formed as a photoelectric conversion layer, and a thickness of 300 A is formed as another conductive type semiconductor layer. The n-type silicon layer 3n was sequentially laminated.

[0059] At this time, the formation conditions of the p-type a-SiC layer 3p are as follows: pressure 120 to 200 Pa, high frequency power density of 0.01 to 0.02 W / cm ² , SiH: hydrogen: hydrogen 0.1% When the gas ratio of CH is 1: 1 1: 1. 6: 1. 8 and the thickness of the layer is equivalent to 80 mm, the discharge is maintained and 0. The supply of ΗΒ and CH diluted to 1% was stopped, and the remaining 70Α was produced.

[0060] Furthermore, in order to form the crystalline photoelectric conversion unit 4 as the second photoelectric conversion unit, the p-type crystalline silicon layer 4p having a thickness of 150A as the one-conductivity-type semiconductor layer is continuously used using a plasma CVD apparatus. A crystalline i-type silicon photoelectric conversion layer 4i having a thickness of 1.5 zm was sequentially stacked as a photoelectric conversion layer, and an n-type crystalline silicon layer 4n having a thickness of 100 A was sequentially stacked as another conductive semiconductor layer.

[0061] Thereafter, the amorphous photoelectric conversion unit 3 and the crystalline photoelectric conversion unit 4 are connected to a plurality of strip-shaped filters. In order to divide it into turns, a YAG second harmonic pulse laser was irradiated from the translucent substrate 1 side to form a connection groove 4a having a width of 60 μm.

Next, a transparent reflective layer (not shown) made of ZnO having a thickness of 900A and a back electrode layer 5 made of Ag having a thickness of 20000A were formed as a back electrode layer by a DC sputtering method. Furthermore, in order to divide the amorphous photoelectric conversion unit 3, the crystalline photoelectric conversion unit 4, and the back electrode layer 5 into a plurality of strip patterns, a YAG second harmonic pulse laser is applied from the translucent substrate 1 side. An integrated hybrid thin film photoelectric conversion device in which a back electrode layer separation groove 5a having a width of 60 xm is formed by irradiation, and strip-like hybrid photoelectric conversion devices adjacent to the left and right are electrically connected in series as shown in FIG. Was made. This integrated hybrid thin-film photoelectric conversion device has 100 stages of hybrid photoelectric conversion devices with a width of 8.9 mm and a length of 430 mm connected in series.

[0063] Finally, the photoelectric conversion device of Example 2 was fabricated by heat-treating the photoelectric conversion device in the atmosphere at an atmospheric temperature of 190 ° C for 60 minutes.

[0064] The integrated hybrid thin-film photoelectric conversion device fabricated in Example 2 has a spectral distribution AMI.

5. Simulated sunlight with an energy density of 100 mW / cm ² was irradiated under the measurement atmosphere and the temperature of the photoelectric conversion device of 25 ± 1 ° C, and the output characteristics of the thin film photoelectric conversion device were measured. Table 2 shows the measurement results for Voc, Jsc, FF, and Eff. In Table 2, Voc is obtained by dividing the actually obtained value by the number of series stages (100), and Jsc is obtained by dividing the actually obtained short-circuit current value by the area of one stage of the photoelectric conversion device. did.

[0065] Table 2 is a table comparing the photoelectric conversion characteristics of the hybrid thin film photoelectric conversion devices manufactured under the conditions of Example 2 and Comparative Examples 3 and 4 described later.

[0066] [Table 2]

[0067] (Comparative Example 3) In Comparative Example 3, almost the same process as in Example 2 was performed, but the point power was different from Example 1 in which heat treatment was performed in the air at an atmospheric temperature of 150 ° C. after the formation of the back electrode layer 5. Table 2 shows the measurement results.

[0068] (Comparative Example 4)

In Comparative Example 4, the same process as in Example 2 was performed, but the formation temperature of the p-type a_SiC layer 3p was 180 ° C., which was different from Example 2. Table 2 shows the measurement results.

[0069] The comparison between Example 2 and Comparative Examples 3 and 4 in Table 2 also shows that the results are the same as those obtained by comparing Example 1 and Comparative Examples 1 and 2.

From the above, according to the method for manufacturing a thin film photoelectric conversion device of the present invention, even when a transparent conductive film having low heat resistance and zinc oxide power is used, its resistivity is not changed. Improve the dopant activation rate of the silicon-based one-conductivity-type semiconductor layer directly formed on the transparent conductive film and the silicon-based one-conductivity-type semiconductor layer, and each junction interface between the other-conductivity-type semiconductor layer and the back electrode layer. An ohmic contact can be ensured. As a result, a thin film photoelectric conversion device exhibiting high performance can be provided at low cost.

Claims

The scope of the claims

[1] A transparent conductive film mainly composed of zinc oxide, one or more photoelectric conversion units including at least a first photoelectric conversion unit, and a back electrode layer are sequentially provided on one main surface of the translucent substrate. A method of manufacturing a thin film photoelectric conversion device comprising:

The photoelectric conversion unit is composed of one conductive semiconductor layer, a photoelectric conversion layer, and another conductive semiconductor layer in order from the light transmitting substrate side.

In addition, the first photoelectric conversion unit is formed directly on the transparent conductive film, and the -conductivity-type semiconductor layer constituting the first photoelectric conversion unit is silicon-based and the silicon-based semiconductor Forming one conductive type semiconductor layer on the transparent conductive film maintained at a temperature of 170 ° C. or lower;

And heating at 170 ° C or higher atmospheric pressure after the back electrode layer is formed

The manufacturing method of the thin film photoelectric conversion apparatus characterized by including.

[2] The method for producing a thin film photoelectric conversion device according to claim 1, wherein the thin film photoelectric conversion device is formed by a CVD method using the transparent conductive film as an element and a source gas containing at least zinc, boron, and oxygen. Furthermore, the manufacturing method of the thin film photoelectric conversion apparatus characterized by the above-mentioned.