JPS5832475A - Manufacture of amorphous silicon solar cell - Google Patents

Abstract

PURPOSE:To form the amorphous silicon semiconductor layer and inverse side conductive region manufacturing solar cell with excellent characteristics by a method wherein the activated hydrogen gas is externally introduced into an evaporator to evaporate silicon impressing negative voltage on the substrate in the evaporator. CONSTITUTION:A vacuum pump is connected to the bell jar as an evaporator through exhaust channel 3 making inside atmosphere of the bell jar highly vacuum while the evaporated substrate 4 arranged inside the bell jar is heated up to specified temperature by means of the heater 5. Then the evaporator 4 is supplied with negaive bias voltage from the DC power supply 6. On the other hand, the hydrogen gas discharge tube 7 is arranged opposite to the evaporator 4 to introduce the activated hydrogen gas from the discharge tube 7 into the bell jar. Then the evaporated substrate 4 is evaporated with silicon, antimony etc. from the heated silicon evaporating agent 8 and antimony, platinum evaporating agents 9, 10 etc. while dangling bond is compensated or enclosed by hydrogen atom forming the excellent amorphous silicon semiconductor layer and the conductive region on the inverse side.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing silicon solar cells.

Recently, solar cells have attracted attention as a device that can directly convert sunlight energy into electrical energy.

Among the various types of solar cells that generate photovoltaic power, amorphous silicon (
Hereinafter referred to as "1-silicon". ) Those with a semiconductor layer are considered to be advantageous in practice. In conventional a-silicon, dangling bonds are formed in which the bonds of tie atoms remain unbonded, and the forbidden band has approximately 10"/3''... A localized state of V occurs, making it difficult to control valence electrons and having low carrier mobility, making it impossible to use it as a semiconductor material for solar cells.

Subsequently, the so-called glow discharge method was developed as a practical method for manufacturing a silicon layer that can be controlled electronically. This is done by introducing silane gas into a vacuum chamber, causing no discharge, and decomposing the silane to generate active silicon atoms and hydrogen atoms. The a-silicon obtained by this glue discharge method is a method of depositing Kame silicon on a substrate with dangling bonds compensated by hydrogen atoms.
-81M, and the concentration of 50M is formed by hydrogen gas.
~500 p, p, wa, K diluted phosphine, dil
Valence electron control is possible by mixing a gas such as Ran or Arsine with silane gas to generate a glow discharge. Furthermore, it has since been reported that a-silicon has the potential to be useful as a material for solar cells.

However, in the above-mentioned glow discharge method, it is extremely difficult to stabilize the plasma even though the structure m of the formed silicon depends on the plasma state of the glow discharge. However, it is almost impossible to form a homogeneous a-silicon film, and in particular, it is impossible to obtain 1-silicon with desired characteristics because the ratio of hydrogen introduction cannot be independently controlled.

(6) In addition, in the glow discharge method, the deposition rate of a-silicon is determined by the state of the plasma, and this is extremely small, on the order of several angstroms per 7 seconds. There are limits to film formation, and continuous film formation by moving the substrates relative to each other is impossible, and it is difficult to handle because it uses dangerous silane gas or even more toxic phosphine gas, dilan gas, arsine gas, etc. This is troublesome, and the gaseous substances accumulate on the inner surface of the vacuum chamber, are dissociated by the subsequent glow discharge, and are mixed into the a-silicon formed on the substrate.
In the end, when using the glow discharge method, there is a limit to the practical scale of the solar cell, which has excellent characteristics in practice. The present invention was developed based on the above-mentioned circumstances, and it is an object of the present invention to provide a method that can advantageously produce solar cells with excellent characteristics. purpose.

(7) A feature of the present invention is that in a method for manufacturing a silicon solar cell having an amorphous silicon semiconductor layer on a substrate, hydrogen gas activated by a device outside the vapor deposition tank is introduced into the vapor deposition tank; A step of forming a shear amorphous silicon semiconductor layer by depositing silicon on the substrate in a state where a negative voltage is applied to the substrate in the vapor deposition tank, and forming a conductive region on the side of the amorphous silicon semiconductor layer opposite to the substrate. and a step of forming.

Embodiments of the present invention will be described below with reference to the drawings.

In the present invention, as shown in FIG. 1, a vacuum pump (not shown) is connected to a pelger 1 forming a vapor deposition tank via an exhaust path 3 having a cylinder 2. For example, the inside of the perger l is 10-3 to 10-9.
The KFi inside the Pelger 1 is softened to a high vacuum state of 1/rr.
Arrange the vapor deposition substrate 4 and heat it to the heater 5) at a temperature of 15
Heating to 0 to 500°C, preferably 250 to 450°C, and applying DC electricity to vapor deposition 6o58-3247
5(3)' Apply a negative bias voltage of 0 to 10 kV to the substrate 4.

Then, while introducing activated hydrogen gas, that is, active hydrogen and hydrogen ions into the Pel jar 1 through a hydrogen gas discharge tube 7 provided in the Pel jar 1 so that its outlet faces the vapor deposition substrate 4, the vapor deposition substrate 4 is The silicon evaporation sources 8 provided opposite to each other are heated to evaporate silicon onto the evaporation substrate 4, thereby forming an a-silicon semiconductor layer in which dangling bonds are compensated or blocked by hydrogen atoms. a- Forming a conductive region on the surface of the silicon semiconductor layer opposite to the substrate to produce a solar cell.

In the above example of the hydrogen gas discharge tube 7, the second
As shown in the figure, one cylindrical electrode member 22 having a gas population 21, and a discharge space member 24 made of, for example, cylindrical glass, surrounding a discharge space 23 and having this one electrode member 22 at one end. , provided at the other end of this discharge space member 24,
The other electrode member 26 is configured with a ring-shaped other electrode member 26 having an outlet 25, and a current or alternating current voltage is applied between the one electrode member 22 and the other electrode member 26 (9). ,
Hydrogen gas supplied through the gas population 21 is supplied to the discharge space 2
3, a glow discharge is generated, whereby active hydrogen consisting of hydrogen atoms or molecules activated by electron energy and ionized hydrogen ions are discharged from the outlet 25. The discharge space member in this illustrated example has a 24-piece double pipe structure and is configured to allow cooling water to flow through it, and 27.28
are the cooling fins of one electrode member 22, where 29ti indicates the cooling water inlet and outlet. The material of the hydrogen gas discharge tube in this example is, for example, aluminum, and the distance between the electrodes is tjlO.
~15 scratches, the other electrode member 26 is set to ground potential, and one electrode member 22 is applied with a voltage of 500 to 800V, preferably 60V.
An AC or DC voltage of about 0 V is applied, and the pressure in the discharge space 23 is 101? It is said to be around @rr. The hydrogen gas to be supplied to the hydrogen gas discharge tube 7 is of high purity, preferably purified by palladium, for example. As shown in Figure 1, Pelger 1 (
10) In addition to the silicon evaporation source 8, a □ evaporation source of an element of group V of the KFM periodic table, such as an antimony evaporation source 9, and a metal evaporation source, a platinum evaporation source 10, are provided, and the evaporation sources 8 to 10 are
A shutter 8 is provided in each of the shutters 8 so as to be openable and closable. Using a substrate made of stainless steel as a vapor deposition substrate and heating it to a temperature of 350°C, first, while introducing active hydrogen and hydrogen ions into the Pel jar 1 through the hydrogen gas discharge tube 7, the inside of the Pel jar 1 is heated. 2 X 10-' To
The silicon evaporation source 118 and the antimony evaporation source 9 are heated to evaporate the evaporation source material while maintaining the reduced pressure state of rr and applying a DC voltage of -3 kV to the evaporation substrate, and open their shutters S. From K, as shown in FIG. 3, a-silicon into which hydrogen was introduced and antimony was contained as an impurity was deposited on the substrate 30.
For example, an n-type layer 31 having a thickness of 50 to 500λ is formed. Next, the heating of the antimony evaporator @ 9 is stopped, and the evaporation by the silicon evaporation source 8 is continued with the shutter S closed, and the n-type layer 31 is coated with silicone (11), for example, which does not contain impurities. 1J132 with thickness 0.5-2 microns
form. Thereafter, the introduction of active hydrogen and hydrogen ions is stopped, the heating of the silicon evaporation source 8 is stopped and its shutter Bt- is closed, and the platinum evaporation source 10 is heated to evaporate platinum, and its shutter 8 is opened. A metal layer 33 made of metal with a thickness of several hundred liters is formed on the i-layer 32, and an electrode body layer 34 made of metal for collecting current is further formed on this metal layer 33 as necessary. If fed, it will be formed into a net shape, thereby producing solar cells.

In the configuration shown in FIG.
An ohmic contact is formed between 1 and
A Schottky barrier is formed at the boundary between the first layer 32 and the metal layer 33, and an electromotive force appears due to the light transmitted through the metal layer 33, causing an increase in the contact between the metal layer 33 or the II'i electrode body layer 34 and the substrate 30. A voltage is generated between the two. The conversion efficiency obtained here is Ml of light...:.

(100 dN/) ON radiation is approximately 3.5 seconds, which can be used in practical use for 10 seconds. In order to form the metal layer 33, K may be a metal with a large work function such as gold or palladium other than platinum.

In addition, in place of electrode body N34, or metal N33 and electrode body layer 340, 8m01 is referred to as 9KITO layer.

A structure may also be provided in which a transparent electrode made of In01 or the like is provided. In this case, the sheet resistance of the transparent electrode is lO
It is preferable that the light transmittance is 85% or more at Ω/d or less.

The present invention F1 or higher, -silicon semiconductor layer (#
! In the example shown in Figure 3', the tin-type layer 31 and layer 32) are formed by vapor deposition of silicon in the presence of active hydrogen and hydrogen ions, so the silicon evaporation source 8 or even the group V element is used. It is possible to individually control the degree of heating of evaporation i19, the degree of activation of active hydrogen, the amount of hydrogen ions and/or the amount of hydrogen ions introduced, and it is possible to form an a-silicon semiconductor layer with desired characteristics, and it is always uniform. It is possible to form a hydrogen-containing a-silicon semiconductor layer under such conditions, and the composition or composition thereof can be made homogeneous. Moreover, the manufacturing speed of the a-silicon semiconductor layer can be easily made several tens of times higher than that of the glow discharge method (for example, (13) 10 to 1 ooi/sec), and
It is possible to uniformly deposit the entire surface of a large-area deposition substrate, and furthermore, by moving the deposition substrate 4 relative to the silicon evaporation source 8, continuous film formation is also possible.

Also, when co-evaporating an element of group Ⅰ or group V of the periodic table together with silicon to control the valence electrons of the a-silicon semiconductor layer, an evaporation source is provided and the state is controlled by opening and closing of the shutter 8 and evaporation. It can be easily controlled by simply turning on and off the heating power source. Therefore, according to the present invention, it is possible to produce a solar cell having an a-silicon semiconductor layer with excellent properties, and therefore with excellent properties, and very advantageously. It is preferable that the hydrogen gas discharge tube 7 is located outside the Pelger 1 which constitutes the vapor deposition tank. That is, hydrogen gas discharge tube 7 #i generates heat due to its operation and reaches 1000°C.
Since the above is also expressed as O high temperature, if left as is, the O ring for vacuum sealing of the Konoha gas discharge tube 7 will melt and deteriorate, and the electrode member 22
, 26 (14), and therefore a cooling mechanism is required.
If the hydrogen gas discharge tube 7 is provided outside the Pelger 1, it is easy to set the four electrode members 28 at ground potential and sufficiently cool them by water cooling, as described above, and a voltage is applied. Therefore, water cooling cannot be used for one electrode assembly 2!11. Regarding this, fin 29
It is easier to provide sufficient cooling than to provide air cooling with a fan or the like. In addition, hydrogen gas discharge tube 7
If K is provided outside the Pelger 1, the electrode member 2. Z
, 26 cleaning, vacuum sealing O-ring replacement, and other maintenance can be performed without contaminating the inside of the deposition tank.

On the other hand, if a hydrogen gas discharge tube is placed inside a Pelger l, atoms will scatter from metal parts such as electrode members, so a fairly powerful cooling mechanism is required, and the electrodes to which voltage must be applied Disposing the members in the Pelger 1 poses a major mechanical problem, and the deposition conditions are also severe. 15) When maintaining the hydrogen gas discharge tube, there is a high possibility that the inside of the Pel Jar 1 will be contaminated, and undesirable impurities such as food, nitrogen, and transition metals may be introduced into the Pel Jar 1.
The a-silicon thus formed has poor characteristics such as low dark resistance and decreased photoresponsiveness.The solar cell manufactured by the method of the present invention has the following properties:
Even if the depletion layer that generates photovoltaic force is of the type formed by the a-silicon semiconductor layer, its specific power is W.
It extends to kIi. For example, in the words in Figure 3, further K1 layer 32
and metal layer 33 below 81 or 81
It is also possible to use a structure in which a photovoltaic force is generated by a barrier formed by forming an insulating layer of N or the like, or as shown in Fig. A transparent conductive layer 41 that is more powerful than an ITO film, an 8mO3 film, or a 1m1O@ film, or #1 the transparent conductive layer 41
A 1[,1 1kO metal layer with a thickness of 0.5 to 2 microns is formed on the substrate, and a layer of 01941 with a thickness of 0.5 to 2 microns is applied on the substrate. Japanese Patent Publication No. 58-32
475(5) - A structure in which a conductive layer 44 made of metal and having a thickness of several hundred amps, for example, is provided through a U-shaped layer 43 for obtaining a contact,
As shown in Figure 5, #! Similar to the 3WJ example, an m-type layer 51 with a thickness of 50' to 400 cm is formed on the metal substrate 50.
Form one layer 52 with a thickness of 0.2 to 2 cm through the
A p-type layer 53 made of a-silicon with a thickness of 50 to 300 mm and containing KfIl as an impurity is formed on this layer 52, and a p-type layer 53 made of a-silicon with a thickness of 50 to 300 mm is formed on this layer 52, and a p-type layer 53 made of a-silicon containing KfIl as an impurity is formed, and a p-type layer 53 made of a-silicon containing KfIl as an impurity is formed thereon. A structure in which a transparent conductive layer 54 and an electrode body layer 55 or a transparent conductive layer 54 are provided to form a space charge electric field, or in this structure, one layer 42 is not provided and a Kp type layer and a type II layer are formed. As shown in FIG. 6, a silicon barrier is formed between the 3M layer 31 and the first layer 32 in the example of FIG. 3 at the boundary with the first layer 32. , metals with high work functions such as gold, platinum,
Transparent metal layer 6 with a thickness of about 100λ made of palladium or the like
0, and an I'rO conductive layer 61 and an electrode body layer 62 are provided on the five layers 32, or other configurations may be used.

(17) As described above, the 1 layer, the 'a type layer and the P type layer are all formed by a 1-silicon semiconductor layer by vapor deposition of silicon in the presence of active hydrogen and hydrogen ions. ! In the layer, group Ⅰ elements such as phosphorus, arsenic, antimony, bismuth, etc. are also present in pl! In the layer, primary materials such as boron, aluminum, gallium, indium, thallium, etc.
Any method can be used to form a conductive layer or the like made of a metal in which group elements are mixed as impurities by vapor deposition in the same way as silicon, but in the present invention, In particular, it is convenient to use metal evaporation, and therefore, four evaporation sources 8 are used as shown in FIG.
- 11 are arranged and used as a silicon evaporation source, a metal evaporation source, a group P element evaporation source and a group Ⅰ element evaporation source,
By controlling the evaporation by each evaporation source, including the opening/closing control of the individual shutters, solar cells having various layer configurations can be manufactured. Here, each evaporation source may be heated by any method such as an electron gun heating method or a resistance heating method. When using a metal plate (18) as a substrate, in addition to stainless steel, molybdenum, tungsten, etc. can be used as the substrate.
Glass plate, quartz plate with metal layer such as molybdenum, tungsten, chromium, etc., several hundred thick gold, platinum and/or FiI 0 film, 8mOB film, ImtOmml
It is also possible to use a device provided with a transparent electrode layer such as the above.

As described above, according to the present invention, silicon hydroxide is deposited while introducing active hydrogen and hydrogen ions into a vacuum chamber.
- A solar cell can be manufactured by forming a silicon semiconductor layer, and as a result, a solar cell with excellent characteristics can be advantageously manufactured.

[Brief explanation of the drawing]

FIG. 1 is an explanatory cross-sectional view showing the configuration of a vapor deposition apparatus used for manufacturing the silicon solar cell of the present invention, and FIG. ! ! ! ! An explanatory sectional view showing an example of a hydrogen gas discharge tube, and Figures #I3 to 6 are explanatory sectional views showing an example of the configuration of a solar cell manufactured by the method of the present invention. 1... Pelger 3... Exhaust path (19) 4... Evaporation substrate 5... Heater 7...
Hydrogen gas discharge tube 21... Gas population 22... Electrode member 23... Discharge space 24... Discharge space member 26... Electrode member 30... Substrate
31... Vortex formation layer 32... 1 layer 33-
...Metal layer 40...Glass plate 41...Transparent conductive layer 42...1 layer 43...*W1
1 layer 44...-conductive layer 50...metal substrate 51...1111 layer 52...1 layer 53
...pH layer 54...transparent conductive layer 60.
...Transparent metal layer 61...ITO conductive conductive interlayer 8 1982-475 (6) Figure 1 Figure 2 Suito Forces

Claims (1)

[Claims] 1) In a method for manufacturing a silicon solar cell having an amorphous silicon semiconductor layer on a substrate, the vapor deposition is performed while introducing activated hydrogen gas into the vapor deposition tank using a device outside the vapor deposition tank. State I in which a negative voltage is applied to the substrate in the tank
The step of depositing silicon on the substrate in step I includes the steps of forming a silicon semiconductor layer and forming a conductive region on the opposite side of the amorphous silicon semiconductor layer from the substrate. Features of amorphous silicon 1IIfi [Method 2]
The step of forming the amorphous silicon semiconductor layer is a step of vapor-depositing silicon alone to form an amorphous silicon-only semiconductor layer, and/or vapor-depositing a dopant consisting of one of a Group 1 element and a Group IIV element of the periodic table together with silicon. 2. A method for manufacturing an amorphous silicon layer according to claim 1, comprising the step of forming a conductor layer on the amorphous silicon layer doped with the dopant. 3) The step of forming the amorphous silicon semiconductor layer includes forming a first amorphous silicon semiconductor layer on the substrate doped with a tenth dopant consisting of one of a group 1 element and a group Ⅰ element of the periodic table; The process comprises stacking and forming a silicon-only semiconductor layer and a second amorphous silicon semiconductor layer doped with a second dopant consisting of the other of the group 1 element and the group Ⅰ element; A method for manufacturing an amorphous silicon solar cell according to claim 1, wherein an electric field of space charges is formed in the layer. 4) The step of forming the amorphous silicon semiconductor layer is performed on the substrate for one cycle A first amorphous silicon semiconductor layer doped with a dopant III consisting of one of Group 1 elements and Group II elements of the Table of Contents, and a second (3) dopant consisting of the other of Group I elements and Group II elements. Formed from the step of laminating and forming a second amorphous silicon semiconductor layer doped with an agent, the amorphous silicon semiconductor layer of tIM1 and III! 2C) The method for manufacturing an amorphous silicon solar cell according to claim 1, wherein a junction is formed in relation to the amorphous silicon semiconductor layer. 5) The step of forming the amorphous silicon semiconductor layer comprises doping the second amorphous silicon semiconductor layer with the 20th dopant at a higher concentration than the second amorphous silicon semiconductor layer. The amorphous silicon solar cell OSH and method according to claim 4, which includes the step of forming layers by laminating them. 6) The step of forming the conductive region is separated from the step of depositing a light-transmissive conductive material on the amorphous silicon semiconductor layer, and the conductive region is formed by K′L·η so that a space charge is formed in the conductive region. A method for manufacturing an amorphous silicon solar cell according to claim 1, 1112, #I3, 4 or #5.