JP2003318422A - Photoelectric converter and method of manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve low conversion efficiency in the conventional method of manufacturing a photoelectric converter utilizing crystalline semiconductor particle. <P>SOLUTION: A large amount of the p-type crystalline semiconductor particle 3 including the oxide layer 6 at the surface is provided on an aluminum layer 1, the aluminum layer 1 and the p-type crystalline semiconductor particle 3 are fused with the heating process, an insulation substance 2 is supplied to fill the space among the crystalline semiconductor particle 3, the oxide layer 6 at the upper part of the crystalline semiconductor particle 3 is removed, and the n-type semiconductor 4 is formed to the part where the oxide layer 6 is removed at the upper part of the crystalline semiconductor particle 3. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric conversion device used for solar power generation and a manufacturing method thereof, and more particularly to a photoelectric conversion device using crystalline silicon particles and a manufacturing method thereof.

[0002]

2. Description of the Related Art The advent of a next-generation solar cell that uses a small amount of silicon raw material and is low in cost is strongly desired. FIG. 4 shows a conventional photoelectric conversion device using grain-shaped or spherical silicon crystal particles, which is advantageous for resource saving. In this photoelectric conversion device, a low melting point metal layer 8 is formed on a substrate 1, semiconductor particles 3 are disposed on the low melting point metal layer 8, and an amorphous semiconductor of the second conductivity type is formed on the semiconductor particles 3. The layer 7 and the transparent conductive layer 5 are formed between the low melting point metal layer 8 and the insulating layer 2 (see, for example, Japanese Patent No. 2641800).

Further, as shown in FIG. 5, an aluminum layer 10 is formed on the metal electrode 1, and the aluminum layer 10 is formed.
The semiconductor particles 3 are arranged on the semiconductor particles 3
A photoelectric conversion device in which a conductive type microcrystalline semiconductor layer 9 and a transparent electrode layer 5 are formed between the aluminum layer 10 and an insulating layer 2 is also disclosed (for example, Japanese Patent Laid-Open No. 3-22837).
No. 9).

[0004]

However, in the conventional photoelectric conversion device shown in FIG. 4, the semiconductor particles 3 and the insulating layer 2 are used.
The recombination rate of carriers is very high at the interface of
Since the carriers generated in the semiconductor particles 3 cannot be taken out well, there is a problem that the conversion efficiency is low.

Further, the conventional photoelectric conversion device shown in FIG. 5 also has a problem that conversion efficiency is low because recombination at the interface between the semiconductor particles 3 and the insulating layer 2 is large.

The present invention has been made to solve the above problems in the prior art, and an object thereof is to provide a photoelectric conversion device having high conversion efficiency and high productivity, and a manufacturing method thereof.

[0007]

In order to achieve the above object, according to the method of manufacturing a photoelectric conversion device according to claim 1,
A large number of p-type crystal semiconductor particles having an oxide layer on the surface thereof are arranged on an aluminum layer to be one electrode, and the aluminum layer and the p-type crystal semiconductor particles are welded by heat treatment,
While filling the insulating material between the crystalline semiconductor particles,
It is characterized in that the oxide layer above the crystalline semiconductor particles is removed to form an n-type semiconductor portion.

It is desirable to perform the heat treatment at 580 ° C. or higher.

Further, it is preferable that the oxide layer of the crystalline semiconductor particles is removed by a reaction with the aluminum layer during the heat treatment so that the crystalline semiconductor particles and the aluminum layer are welded.

Further, according to the photoelectric conversion device of the fourth aspect, a large number of p-type crystal semiconductor particles are provided on the aluminum layer to be one of the electrodes, and an insulating material is filled between the crystal semiconductor particles. In the photoelectric conversion device in which an n-type semiconductor layer is formed on the crystalline semiconductor particles, a reaction aid for controlling the reaction between the aluminum layer and the oxide layer formed on the surface of the crystalline semiconductor particles in the aluminum layer. It is characterized by including.

The reaction aid is preferably boron, zinc, silicon, oxygen, carbon or nitrogen.

Further, according to the method of manufacturing a photoelectric conversion device in accordance with a sixth aspect, a large number of p-type crystal semiconductor particles are arranged on an aluminum layer which is to be one of the electrodes, heat-treated and welded to form the crystal. An oxide layer is formed on the surface of the semiconductor particles, an insulating material is filled between the crystal semiconductor particles, and the oxide layer above the crystal semiconductor particles is removed to form an n-type semiconductor layer.

The oxide layer is preferably formed by acid treatment.

It is desirable to use nitric acid or hydrogen peroxide for the acid treatment.

It is desirable that the acid treatment is performed at 50 ° C. or higher and 300 ° C. or lower.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the drawings. FIG. 1 is a cross-sectional view showing an embodiment of a photoelectric conversion device according to the present invention, in which 1 is an aluminum layer, 2 is an insulating layer, 3 is a first conductivity type granular crystalline silicon, and 4 is a second layer.
A conductive type semiconductor layer, 5 is an upper electrode layer, and 6 is an oxide layer.

The aluminum layer 1 is made of aluminum, an aluminum alloy or the like, and a metal, glass, ceramics, resin or the like as a base material may be provided below the aluminum layer 1. Further, a reaction aid for promoting the formation of the oxide layer 6 around the granular crystalline silicon 3 is included inside or on the surface of the aluminum layer 1. As such a reaction aid, boron, zinc, silicon, oxygen, carbon and nitrogen are preferable.

The insulating layer 2 is filled between the granular crystalline silicon 3 in order to separate the positive electrode and the negative electrode. The insulating layer 2 is made of a glass material, a resin material, or the like. The insulating layer 2 is preferably made of a material that has a small reaction with the oxide layer 6. If the insulating layer 2 reacts too much with the oxide layer 6, the oxide layer 6 is destroyed and the characteristics deteriorate, which is not preferable.

Although the p-type granular crystalline silicon 3 is made of silicon, the silicon may contain B and Al as trace elements. The granular crystalline silicon 3 can be formed by a vapor phase growth method, an atomizing method, a direct current plasma method or the like, but a melt dropping method of dropping the melt in a non-contact environment is preferable. For example, B and Al exhibiting p-type by being added to silicon are 1 × 10 ¹⁴ to
About 10 ²⁰ atm / cm ^{3 was} added.

The p-type granular crystalline silicon 3 has an oxide layer 6 on its surface. The oxide layer 6 is formed at the interface between the P-type crystalline silicon particles 3 and the insulating layer 2. By forming the oxide layer 6, recombination at the interface between the crystalline silicon particles 3 and the insulating layer 2 can be reduced and the conversion efficiency can be improved. The oxide layer 6 has a thickness of 500 in an atmosphere containing oxygen.
It is desirable to form it at a temperature of not lower than 14 ° C and not higher than 14 ° C. Fifty
A temperature of 0 ° C. or lower is not preferable because the quality of the oxide layer 6 is deteriorated, and a temperature of 1414 ° C. or higher is not preferable because the silicon 3 is melted. After forming the oxide layer 6, annealing may be performed in an atmosphere containing hydrogen. Hydrogen is preferable because it inactivates defects in the granular crystalline silicon 3 and improves the characteristics. Hydrogen annealing is preferably performed after forming the oxide layer 6, and the annealing temperature is 900 ° C.
Above 1350 ° C. is preferable.

The n-type semiconductor layer 4 is formed by plasma doping method, thermal diffusion method, ion implantation method, thermal CVD method, plasma C
It is formed by a VD method, a catalytic CVD method, a sputtering method, or the like. Further, the film thickness of the n-type semiconductor layer 4 is 5 nm or more and 500 n or more.
It is preferably m or less. When the film thickness of the n-type semiconductor layer 4 is less than 5 nm, the film 4 is formed due to the film thickness distribution of the n-type semiconductor layer 4.
Is not preferable because there is a risk of breaks. When the film thickness of the n-type semiconductor layer 4 exceeds 500 nm, the light absorption of the n-type semiconductor layer 4 increases and the conversion efficiency decreases, which is not preferable. The n-type semiconductor layer 4 is added with a small amount of P or the like exhibiting n-type. The concentration of the trace element added is, for example, 1 × 10 ¹⁴ to 10
It is about ²² atm / cm ³ . In addition, the n-type semiconductor layer 4
May be crystalline, microcrystalline, or amorphous. Also, n
The shaped semiconductor layer 4 is formed of silicon, silicon carbide, silicon germanium, or the like.

The upper electrode film 5 is formed of tin oxide, indium oxide, zinc oxide or the like by a sputtering method or the like. It is also possible to provide an antireflection effect by adjusting the film thickness and the refractive index. Further, an auxiliary electrode may be formed on the silver or copper paste in an appropriate pattern. The method of forming the auxiliary electrode includes an inkjet method, a transfer method, a screen printing method, and the like.

FIG. 2 is a diagram showing a method of manufacturing the photoelectric conversion device according to the first aspect. First, p having an oxide layer 6 on the surface
The shaped crystalline silicon particles 3 are arranged on the aluminum layer 1 (FIG. 2A). As the disposing method, any of a vibration alignment method, a suction method, a printing method, an electrostatic alignment method and the like may be used. Next, the crystalline silicon particles 3 and the aluminum layer 1 are heated to 577 ° C.
It heat-processes at the above temperature and welds (FIG.2 (b)). At this time, in order to control the reaction between the oxide layer 6 and the aluminum layer 1, boron, zinc, silicon,
A reaction aid consisting of oxygen, carbon and nitrogen is added. In addition, when welding, aluminum or boron is added to the crystalline silicon particles 3
The p ⁺ region may be simultaneously formed by diffusing it. The appropriate diffusion depth of aluminum is 0.1 μm or more and 50 μm or less. Next, the insulating layer 2 is formed (FIG. 2C). If the insulating layer 2 covers the upper portions of the crystalline silicon particles 3 too much, p
This is not preferable because the area of the n-junction is reduced and the conversion efficiency is reduced. When the ratio of the cross-sectional area of the pn junction and the cross-sectional area of the crystalline silicon particles 3 is defined as the aperture ratio, the aperture ratio is 50%.
It is preferably at least 80%, more preferably at least 80%. Next, the oxide layer 6 on the crystalline silicon particles 3 is removed (FIG. 2D). To remove the oxide layer 6, a wet etching method using hydrofluoric acid or the like, a dry etching method such as plasma ashing, or the like is used. Next, the n-type semiconductor layer 4 is formed on the Si sphere 3
It is formed on the upper portion (FIG. 2E). Next, the upper electrode 5 is formed (FIG. 2F). Further, fingers or bus bars (not shown) may be appropriately provided as auxiliary electrodes.

FIG. 3 is a diagram showing a method for manufacturing a photoelectric conversion device according to a sixth aspect. First, the p-type crystalline silicon particles 3 are arranged on the aluminum layer 1 (FIG. 3A). As the disposing method, any of a vibration alignment method, a suction method, a printing method, an electrostatic alignment method and the like may be used. Next, the crystalline silicon particles 3 and the aluminum layer 1 are heated to a temperature of 577 ° C. or higher and welded (FIG. 3B). During the heating step, the oxide layer 6 and the p ⁺ region may be simultaneously formed on the surface of the crystalline silicon particles 3. Next, the oxide layer 6 is formed on the surface of the crystalline silicon particles 3 (FIG. 3C). The oxide layer 6 is preferably formed by acid treatment. The acid treatment preferably uses nitric acid or hydrogen peroxide. The acid treatment is preferably a heat treatment at 50 ° C. or higher and 300 ° C. or lower. Next, the insulating layer 2 is formed (FIG. 3D). next,
The oxide layer 6 on the crystalline silicon particles 3 is removed. (Fig. 3
(E)) Next, the n-type semiconductor layer 4 is formed on the Si sphere 3 (FIG. 3 (f)). Next, the upper electrode 5 is formed (FIG. 3).
(G)).

[0025]

Example 1 Next, an example of the photoelectric conversion device of the present invention will be described.

First, one layer of granular crystal p-type silicon 3 having an average particle diameter of 700 μm and having an oxide layer 6 having a thickness of 15 nm is densely arranged on an aluminum substrate 1 and heated to 650 ° C. to heat the substrate 1 and the granular crystalline silicon. 3 was welded. Table 1 summarizes the results of evaluating the characteristics by changing the reaction aid added to the aluminum substrate 1 used at this time. Next, a boron oxide-based glass paste 2 having a glass transition point of 500 ° C. was filled in the granular crystalline silicon 3 and heated and baked to form the insulating layer 2. An n-type crystalline silicon layer 4 having a thickness of 30 nm was formed thereon by plasma CVD. Next, a protective film 5 made of tin oxide was formed to a thickness of 100 nm by a sputtering method and evaluated. The conversion efficiency when the granular crystal p-type silicon 3 without the oxide layer 6 was used was 7.8%.

[0027]

[Table 1]

As can be seen from the above results, by using the granular crystal p-type silicon 3 having the oxide layer 6, the conversion efficiency is improved to 10% or more. Further, it is preferable to add boron, zinc, silicon, oxygen, carbon, and nitrogen as a reaction aid in the aluminum layer 1 because the conversion efficiency is improved to 11% or more.

[0029]

[Embodiment 2] First, an average grain size of 2 on an aluminum substrate 1.
One layer of granular crystal p-type silicon 3 of 00 μm is densely arranged,
The substrate 1 and the granular crystalline silicon 3 were welded by heating at 600 ° C. Next, it was dipped in heated hydrogen peroxide to form an oxide layer 6 on the surface of the granular crystalline silicon 3. Next, a zinc oxide-based glass paste having a glass transition point of 530 ° C. was filled in the granular crystalline silicon 3 and heated and baked to form the insulating layer 2. Then, an n-type crystalline silicon portion 4 is formed thereon by ion implantation.
Was formed to a thickness of 10 nm. Next, a protective film 5 made of zinc oxide was formed to a thickness of 100 nm by a sputtering method and evaluated. As a result, a conversion efficiency of 10.5% could be obtained, which was much higher than the conversion efficiency of 7.8% of the element having no oxide layer 6. The acid treatment temperature was changed from 50 ° C. to 300 ° C. and evaluated, and all showed similar effects. Further, the same effect was exhibited when the hydrogen peroxide was changed to nitric acid.

[0030]

As described above, according to the method of manufacturing a photoelectric conversion device of the first aspect, a large number of p-type crystalline semiconductor particles having an oxide layer on the surface thereof are provided on the aluminum layer which serves as one electrode. Since heat treatment is performed to fuse the crystalline semiconductor particles with each other, an insulating material is filled between the crystalline semiconductor particles, and the oxide layer above the crystalline semiconductor particles is removed to form an n-type semiconductor layer.
The recombination at the interface between the crystalline silicon particles and the insulating layer can be reduced to improve the conversion efficiency, and the photoelectric conversion device having high conversion efficiency can be manufactured.

Further, in the photoelectric conversion device according to the fourth aspect, the reaction with the oxide layer formed on the surface of the crystalline semiconductor particles arranged in large numbers in the aluminum layer to be one electrode is controlled. Since it contains a reaction auxiliary agent for forming the oxide layer, an oxide layer can be easily formed on the surface of the crystalline semiconductor particles, recombination at the interface between the crystalline silicon particles and the insulating layer can be reduced, and photoelectric conversion with high conversion efficiency can be achieved. A device can be provided.

Further, according to the method of manufacturing a photoelectric conversion device of claim 6, a large number of p-type crystal semiconductor particles are arranged on an aluminum layer to be one of the electrodes, heat-treated and welded.
An oxide layer is formed on the surface of the crystalline semiconductor particles, an insulating material is filled between the crystalline semiconductor particles, and the oxide layer above the crystalline semiconductor particles is removed to form an n-type semiconductor layer. It is possible to reduce recombination at the interface between the particles and the insulating layer to improve the conversion efficiency, and it is possible to manufacture a photoelectric conversion device having high conversion efficiency.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a photoelectric conversion device of the present invention.

FIG. 2 is a cross-sectional view showing an embodiment of a method for manufacturing a photoelectric conversion device of the present invention.

FIG. 3 is a cross-sectional view showing another embodiment of the method for manufacturing a photoelectric conversion device of the present invention.

FIG. 4 is a cross-sectional view showing a conventional photoelectric conversion device.

FIG. 5 is a cross-sectional view showing another conventional photoelectric conversion device.

[Explanation of symbols]

1 ... substrate 2 ... Insulating layer 3 ··· First conductivity type granular crystalline silicon 4 ... Semiconductor part of the second conductivity type 5 ... Upper electrode film 6 ... Protective layer 7 ... Amorphous semiconductor layer of second conductivity type 8 ... Low melting point metal layer 9 ... Second-conductivity-type microcrystalline semiconductor layer 10 ... Aluminum paste

Continued front page    (72) Inventor Hisao Arimune             6 at 1166 Haseno, Jamizo-cho, Yokaichi-shi, Shiga               Kyocera Corporation Shiga Yokaichi Factory F term (reference) 5F051 AA02 AA03 CB04 CB13 CB19                       CB24 CB27 CB29 CB30 DA03                       DA09 DA20 FA22 GA02

Claims (9)

[Claims] 1. A large number of p-type crystal semiconductor particles having an oxide layer on the surface thereof are arranged on an aluminum layer to be one electrode, heat-treated and welded, and an insulating substance is filled between the crystal semiconductor particles. At the same time, the oxide layer above the crystalline semiconductor particles is removed to form an n-type semiconductor layer, which is a method for manufacturing a photoelectric conversion device. 2. The method for manufacturing a photoelectric conversion device according to claim 1, wherein the heat treatment is performed at 580 ° C. or higher. 3. The photoelectric conversion device according to claim 1, wherein the oxide layer of the crystalline semiconductor particles is removed by a reaction with the aluminum layer during the heat treatment, and the crystalline semiconductor particles and the aluminum layer are welded to each other. Method of manufacturing converter. 4. A large number of p-type crystal semiconductor particles are provided on an aluminum layer to be one electrode, and an insulating material is filled between the crystal semiconductor particles to form an n-type semiconductor layer above the crystal semiconductor particles. In the formed photoelectric conversion device,
A photoelectric conversion device, wherein the aluminum layer contains a reaction aid for controlling the reaction between the aluminum layer and the oxide layer formed on the surface of the crystalline semiconductor particles. 5. The photoelectric conversion device according to claim 4, wherein the reaction aid is any one of boron, zinc, silicon, oxygen, carbon and nitrogen. 6. A large number of p-type crystal semiconductor particles are disposed on an aluminum layer to be one electrode and heat-treated for welding to form an oxide layer on the surface of the crystal semiconductor particles. A method for manufacturing a photoelectric conversion device, characterized in that an insulating material is filled in between and an oxide layer above the crystalline semiconductor particles is removed to form an n-type semiconductor layer. 7. The method for manufacturing a photoelectric conversion device according to claim 6, wherein the oxide layer is formed by acid treatment. 8. The method for manufacturing a photoelectric conversion device according to claim 7, wherein nitric acid or hydrogen peroxide is used for the acid treatment. 9. The method for manufacturing a photoelectric conversion device according to claim 7, wherein the acid treatment is performed at 50 ° C. or higher and 300 ° C. or lower.