JPS59161079A - Manufacturing method of photoelectric conversion element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to increasing the efficiency of an amorphous silicon photoelectric conversion element. Currently, attempts are being made to improve the efficiency of amorphous silicon photoelectric conversion elements by various means, one of which is an attempt to increase the amount of light incident on the photoactive region. Therefore, in the optically forbidden path of type 1 amorphous silicon, which is the photoactive region, (
(Hereinafter, the optically prohibited path will be referred to as Eop t), which is wider than E.
Substances with opt (such substances are called window materials)
Attempts have been made to form an element by arranging the light on the light incident side. Such window materials include amorphous silicon carbide (a type of silicon with carbon and nitrogen bonded to it).
2-5iCx) and amorphous silicon nitride (hereinafter a-5iNy) were autopsied, and boron-topped p-type a-3i (4 is partially put into practical use.However, The above a-5i'C) (and 5iNy) are inherently difficult to conduct electricity, and when they are used as a window, there is a problem that the air conductivity decreases. .

In order not to reduce the discharge conductivity, a-5iCx
or a-8INy, the value of x+y is set to dog, and Eo
It was not possible to increase pt. For example a”5
iCL-(z is Eopt) It is said that it is best to use Eopt from 1.9 to 2.0eV in terms of balance with electrical conductivity, but the electrical conductivity at this time is about 10'5-cm' Since Eopt is still low, it acts as a resistance component in the photoelectric element, which is disadvantageous to improving efficiency.Therefore, even if Eopt is made wider than this, the benefit of taking in short wavelength light is outweighed by the resistance component. As a result, the overall photoelectric conversion efficiency is adversely reduced by the use of such a wide gap window material.

As a result of intensive studies from the above viewpoint, the present inventors found that Eopt increases in amorphous silicon formed by glow discharge decomposition using disilane gas (hereinafter amorphous silicon will be referred to as a-5i:H). Obtained (% Gansho 5'7-1
34-709) As a result of further investigation, a-5i:
The p-type a-5i:H obtained by doping with a substance imparting HKp-type conductivity has an Eop of more than 1.70 eV.
t, and its tetraelectric constant is 1,0'S-cm-'
It was more than that. That is, the present inventors thus obtained p-type a-3i:H, which was formed by glow discharge using disilane and a substance imparting p-type conductivity.
discovered that the material had properties suitable for use as a window material for photoelectric conversion elements, and completed the present invention.

That is, the present invention provides a pin-type amorphous silicon power conversion element comprising (1)
The p-type amorphous silicon layer is formed by glow discharge decomposition of a mixed gas consisting of disilane and an n-type conductivity imparting substance, and as a result of the decomposition, the optical forbidden path of the p-type silicon layer is (11) and the p-type amorphous amorphous layer is arranged on the light incident side. An amorphous silicon photoelectric conversion element characterized by: In the method for manufacturing a pin-type NRICON photoelectric conversion element, a mixture of disilane and an n-type conductivity type imparting substance is introduced into a gasket glow discharge chamber, and the above 77 runs per m-amount per p
Applying energy of less than l-OKJ, glow discharge decomposition produces pJ'(l) amorphous which has a wide optical forbidden path as well as a wide optical forbidden path in the type 1 amorphous silicon layer. 1. A method for manufacturing an amorphous silicon photoelectric conversion element, comprising forming a silicon layer and performing the decomposition so that the formed p-type silicon layer is formed at a position 4IN1 of light incidence.

It provides:

The present invention will be explained in detail below.

The pin-type non-crystalline silicon photoelectric conversion element of the present invention has at least this p-type amorphous silicon layer (a-3i: H
) or disilane and an n-type conductivity imparting substance is decomposed by glow discharge.

In the present invention, disilane has the general formula Sin'H2n+2
It is represented by / corresponds to n-2 among silanes,
It has the chemical formula 5I2H6. Of course, it is preferable to use disilane with high purity, but tripran, tetrasilane, etc. (including the above general formula tr (where n23.4)) behave in the same way as disilane in glow discharge. Being there 1
For example, there is no problem.

I don't care if a small amount of mono 7 run is mixed in. N/Ran can be produced by a physical synthesis method, for example, by silently discharging monosilane (n-1 in the general formula above), which partially changes to disilane, which is then separated and heated, or by a chemical synthesis method. However, in order to industrially produce photoelectric conversion elements in large quantities, it is practical to use chemical synthesis methods (for example, methods such as reducing hexachlorone 7rane) that can produce large quantities of products of stable quality. It is convenient.

However, the substance that imparts p-type conductivity is, for example, diborane (B2H6), and it is usually preferable to use it diluted with diluted scum such as H2 or He from the viewpoint of safety and control of doping amount. Yes. The ratio of these gases to Dinolane is 0.1 to 0.5 parts by volume per 1.00 parts by volume of sifuran.
This is the capacity part.

In the present invention, the silicon layer constituting the n-layer or i-layer other than the p-type layer is grown using any silane formed by the general formula 5InH2n+2 (n-1 to 3), including monosilane gas, as a raw material gas. Obtained by electrical discharge decomposition.

Preferably, however, as shown in the reference example, 165-1
67 Eopt f monosilane (the above general formula (
/C, n-1) is used. Shinran (also n
= 2) or trisilane (when using the same (n = 3), p-type a-3i:H is 3KJ/g as shown in the example.
It can be formed by applying energy of 3+2H6 or less. Note that PH3 (phosphine), ArH3 (arsine), etc. are used as the n-type conductive material.

A compound such as Sn+Ge can also be added to the oxide.

In short, the Eopt of these amorphous substances is located on the light incident side: p-type a-3i:Hj! 2 should also be small. Therefore, a-5i as used in the prior art
:F :H, a-3i :Ge :H, a-5i :S
n:H etc. can be used in the present invention without any problem.

In the present invention, disilane, which is a raw material for forming U:, p-type a-3i:H, and p-type conductivity imparting substance are diluted and mixed into the diluted scum. is preferably He, Ar, H2, etc.

Since the reproducibility of photoelectric characteristics is improved when diluent gas is used, it is thought that it probably has the role of reducing the influence of trace impurities and mitigating damage to the film caused by plasma. The dilution ratio is not particularly limited, but it is within the range of 5 to 2.0%, which is convenient for production, and the above-mentioned effects are greatly exhibited.

Of course, i type a-5i:H or n type a-3i:H
The use of a diluent gas during formation is also preferred for similar reasons.

As described above, the p-type amorphous phosphoric acid layer of the present invention is formed by decomposing a mixed residue consisting of disilane, a p-type conductivity-imparting substance, and preferably a diluent gas by a conventional glow discharge that is known per se. It has an optical forbidden path wider than the optical forbidden band "1" of the l-type amorphous silicon layer, and the photoelectric conversion element of the present invention has such a p-type amorphous silicon layer disposed on the light incident side. Do it with something like that.

In order to arrange the p-type amorphous silicon layer of the pin-type photoelectric conversion element at 1νIIK of light incidence, as will be detailed later, (1) an opaque material such as stainless steel;
When using one film, silicon layers are formed in the order of n-type, i-type, and p-type from the substrate side, and a transparent electrode is formed on the outside of the p-type silicon layer. (11) When using a transparent substrate such as a glass substrate, in addition to the above, p-type, i-type
A silicon layer may be formed in the order of type and n type, and the substrate side may be set as the light incident side.

In the present invention, in the above case, a p-type amorphous silicon layer having an optical forbidden band 1 which is wider than that of an l-type amorphous silicon layer is used as a p-type amorphous silicon layer of a pin-type amorphous silicon photoelectric conversion element. The present invention provides a method for manufacturing a silicon photoelectric conversion element as a layer, in which a mixture of disilane, a p-type conductivity-imparting substance, and preferably a diluent gas described above is supplied into a glow discharge chamber, and a non-run unit is formed by glow discharge. A p-type amorphous silicon layer is formed by applying an energy of T or less to FA per mass, and the decomposition is performed so that the p-type silicon layer is located on the light incident side. I'm going to do it.

In the present invention, the glow discharge energy (rJ: ) given per unit mass of silane (h) is equal to or less than OKX.

This is the Eopt of p-type asi:H], 70eVJ:
This is in order to maintain a large diameter and satisfy the performance as a window material. That is, as shown in the example below, Eop
t changes depending on the glow discharge energy and increases in the region where the energy is small, but as is clear from the similar reference examples mentioned later, a-8i :l(
The Eopt of p-type a-5i:H is approximately 1.65 to 1.67 eV, and by selecting the energy range for applying disilane as a raw material gas to 10 KJ or less as described above, the Eopt of p-type a-5i:H can be increased. l type a-5i: Eo of H
The requirement of the present invention that the pt width is also sufficiently large is fully satisfied.

-Also, the lower limit value of glow discharge energy is sufficient as long as it can form a stable glow discharge state, and this value varies depending on the conditions of the claw discharge equipment and the raw material waste used, but a preferred specific example is Examples include Jinran alone, helium (He), and archon (Ar).
0.5 in the case of Jinran that has been sheathed with W's Takusaku Kasu.
KJ/g-Si2H6 or more, when diluted with hydrogen (H2) or \15KJ/g SI 2
It is H6 or higher.

In summary, in the present invention, the preferable range of glow discharge energy given to the formation of p-type a-5izH is 05 to 10 KJ/g-Si.

It is H6. Even when energy outside this range is supplied, the effects of the present invention cannot be expected. i.e. 10KJ
/g-3i2! (When applying energy exceeding 6, as shown in the comparative example, Eopt becomes small and the performance as a window material is not exhibited, and 0.5 KJ/g-
When the energy is smaller than 8i□H6, the discharge itself does not occur, and even if discharge occurs, the discharge is not stable and the formation of p-type a-3i:H itself becomes a problem.

In the present invention, the glow discharge energy per unit mass of disilane is calculated using the following formula.

For example, the energy value when power of IOW is applied to 500 CC/min of Jinlan (Si2H6) diluted with helium (He) to a volume of 1% is calculated as follows.

Average molecular weight = (62,2], 84X 0.1+4.0
026X O,9) =9.824 (g)Si2H6
The weight fraction is 62.2184 x 0.1 /9.82
4=0633. Substituting these into the above equation (I), we get Jinran unit 0 0.633 = ] 732CJ/g 5jzH6) Now, if 103J is expressed as KJ, the above energy value is approximately 1
．． It can be expressed as 7KJ/g-812H6.

In the present invention, when forming p-type a-3i:H,
It is preferable to increase the raw material gas flow rate.

In the above energy calculation formula (i), the flow rate is included in the denominator, and if the flow rate is increased, the glow discharge power that can be applied can be increased by that amount, and the allowable range of power variation is also increased, making discharge management easier. 3, and as the flow rate increases, the formation rate of a-3i:H also increases. In addition to these advantages, p-type a-5i:H
A favorable result is also obtained in that the variation in the 4% rate of is reduced. It is difficult to specifically and unambiguously indicate a preferable flow rate range because the range varies depending on the shape of the a-5i:H forming equipment, capacity material, etc. Examples are shown in Examples below.

In the present invention, the temperature when forming p-type a-3i:H is preferably maintained at 450°C or less, preferably from 100 to 400°C.

When the glow discharge energy is the same, Eopt will be larger at a lower temperature, but at a temperature lower than 100°C, the a-3i:H film formation will not proceed effectively, and 1M peeling may occur or a yellow color may occur. However, the object of the present invention cannot be achieved due to the generation of amorphous silicone powder. Also 400℃
Is there a problem with the formation of a-3i:H at temperatures exceeding this temperature?If the temperature rises further, the electric quality such as Eopt deteriorates, and at such temperatures there are problems with the heat resistance of the substrate and electrodes. is shown in close-up. That is, it is better to avoid forming a-5i:H at temperatures exceeding 400 °C, since the efficiency of the d1 photovoltaic element also decreases at temperatures where the substrate or electrodes will develop defects due to heat. .

Furthermore, in the present invention, the formation of p-type a-3i:H can be improved by increasing the pressure to 1 to 10 Torr. The reason why the dust efficiency improves is unknown, but due to the increase in pressure, the mean free path of the plasma becomes smaller, so that the plasma is directly connected to the substrate or electrode. It is thought that it does not work to damage H etc.

There are no particular limitations on the material of the substrate or the materials of the first and eleventh electrodes used in the present invention; conventionally used materials can be usefully used.

For example, the substrate may be insulating or conductive, transparent or opaque.

Specifically, a film or plate-shaped abrasive material made of a substance such as glass, alumina, silicon, stainless steel, aluminum, molybdenum, or a heat-resistant polymer can be effectively used as the substrate. As the first and eleventh electrode materials, transparent or translucent materials must of course be used on the light incident side, but there are no other restrictions. Aluminum, molybdenum, nichrome, TO
Thin films or thin plates of tin monoxide, stainless steel, etc. are effectively used as electrode materials.

First, regarding an embodiment of the present invention, a case where a transparent substrate is used will be described. A glass substrate provided with a transparent No. 1 electrode is placed in a reaction chamber capable of glow discharge, and heated and maintained at a temperature of 100 to 400° C. under reduced pressure. there p
A type of conductivity imparting substance, Sifuran, and a diluent gas are introduced as raw materials, and a glow discharge energy of 10 KJ or less is applied per unit mass of Sisolane, and glow discharge is performed at a pressure of 1 to 10 Torr. In this way, p-type a-3i:H is
Formed in a layer on the electrode. Then, by introducing silane and diluted residue, type 1 a-
3i: H layer is formed by glow discharge. Next, a substance imparting n-type conductivity, 7 run, and diluted residue are introduced as raw materials, and an n-type a-si:I (layer) is formed by glow discharge.Finally, an 11th electrode is formed to form the present invention. A photoelectric conversion element is obtained.

Further, in addition to the above embodiment, a photoelectric conversion element in which light is incident from the opposite side of the substrate II]+1 is also possible. In this case, the n-type, l-type, and p-type layers may be formed in this order from the substrate side, and a transparent second electrode may be formed on the p-type a-5i:H layer.

The above embodiment is a pin type A-3 in one glow discharge chamber.
I have shown an example of forming i:H. Of course, these a-3
i:H can be formed in separate, connected glow discharge chambers.

In addition, in the present invention, p-type a-si:) (layer thickness is used at 50 to 500A.
layer, type 1 a-3i: H layer) enjoyment (d each 50-5
00A, about 3000-7500λ.

As described above, the present invention provides a novel photoelectric conversion element in which a new window material (aS+#C) (without using carbon or nitrogen) is formed.

Since it is not necessary to use hydrocarbons, which are the raw materials for the formation of carbon/carbon-C, such as a-5iCx, there is no need to use carbon deposits inside the claw discharge chamber, and the problem of its removal is eliminated. In addition, hydrocarbons can be removed from the raw material gas, which reduces the complexity of raw material management and further reduces Eopt.
There is no need to control the composition ratio of SN and C in order to manage conductivity, and the window material can be formed simply by using disilane as a raw material, which is an excellent effect.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Examples 1 to 9 (Eop of p-type amorphous 7-licon thin film
Measurement of t) A capacitively coupled high frequency plasma 7°C VD (Chem
A 7059 glass substrate manufactured by Corning Corporation was installed in the substrate installation part of the ical vapor deposition device.

By the oil diffusion pump! While evacuation to 710-7 Torr or less, the temperature of the substrate installation part (6 m degrees for thin film formation)
It was heated so that it became the value shown in Table 1.

Disilane diluted with He (dilution ratio 'S i2 H6/
He -1/9) and H2 diluted B2H6 (dilution ratio B
2H6/H2=1/99) was introduced, and the flow rates and glow discharge power shown in Table 1 were added to form a p-type amorphous silicon thin film.

The flow rates of disilane and B2H6 in Table 1 indicate the total flow rate including the diluent gas.

1. The formation time of the special film is approximately 13 minutes 40 seconds, and approximately 500
A thin film of OA was formed. Eopt is calculated by measuring the light absorption coefficient α of the thin film with a spectrophotometer, and then calculating the energy of the incident light (hν
) with respect to (αhν), and the straight line portion was extrapolated to obtain the value of the intercept with the hν axis. The measurement of the electric current was carried out by forming electrode basins with an interval of 200 μm, applying a voltage between the electrodes, and applying a current (jell).

As a reference example, 17 g of disilane and monosilane f25I
-812H6 and the Eo of the 7-recon film obtained by glow discharge with an energy of 30 KJ/g-3iH.
The pt values were 1.75 eV and 64 eV, respectively.

That is, as shown in Table 1 above, the discharge energy is 10KJ.
/g Si,,H6 or less and by appropriately selecting the formation temperature, the requirements of the present invention can be satisfied.

Examples 10 to 12 (Creation and characteristic measurement of photoelectric conversion elements) Using the plasma CVD apparatus used in Examples 1 to 9, pi
An n-type photoelectric conversion element was formed and its characteristics were determined. That is, a glass substrate having a transparent electrode was placed in the CVD apparatus. The mixture was evacuated to 10-7 Torr or less using an oil diffusion pump, and then heated to a temperature of 250°C. 1) Disilane 50 used in the example described above, assuming a toe pink ratio (capacity ratio of B2H6/Si2H6) of 2%.
CC/min, B2H610 diluted to 01vo1% in B2
CC/min was introduced, glow discharge was performed for 30 seconds at a pressure of 2 Torr, and a p-type amorphous Noricon thin film was formed to a thickness of about 10 OA by giving the glow discharge energy shown in Table 2. For example, when the claw discharge power is 2.5 W, the discharge energy is calculated to be about 1.7 KJ/g-'Si□H6.

The formation temperature gradually increased to 280℃ and the hindlimb non-run 5
00 CC/min and a glow discharge energy of about 26 KJ/g 5j2H6 at a pressure of 5 Torr to form a type 1 amorphous silicon thin film with a thickness of about 4200 A for 2 minutes. Next, 50 CC/min and 10 CC/min of PH3 diluted with silane and B2 to 0.1 vol.
The film was formed to a thickness of about 1ooX for 0 seconds. Next, an aluminum-lamb thin film was formed by vacuum evaporation to form a back electrode. For comparison p
A photoelectric conversion element was fabricated under the same formation conditions as in the above example, except that the energy used to form each type of amorphous silicon film was different. Table 2 shows the characteristics obtained when AMl light was irradiated from the substrate side using Solar/Umulator.

In the example of the present invention, compared to the comparative example, the open circuit voltage (V
oc) increased by 0.12 V and reached 085-089■. The short-term direct current (Dsc) increased by 20-50% and reached 12.6 mA/cm2. The photoelectric conversion efficiency showed an excellent value exceeding 6%. In particular, as in this example (pin-type amorphous silicon, the total formation time of the sand film is 3 minutes and 10 seconds, which is less than 1/10 of the known technology, yet the above conversion efficiency is achieved. What was achieved indicates that the effects of the present invention are significantly superior.

Table 2 Example 13 This example differs from Examples 10 to 12 by 1α in that the i-type exocrystalline silicon thin film of the photoactive layer is formed using monosilane SiH4 as a raw material.

A pin-type photoelectric conversion element was formed using the high-frequency plasma CVD apparatus used in the example of Hikari no Practical Example 2. That is, after forming a transparent 8JJ electrode on a glass substrate, it was placed during CVD deposition. By the oil diffusion pump! l) 10-7 Torr
While fully evacuating A, the temperature of the substrate was increased to 260°C. The doping ratio was 2%, and 50% each of the disilane and B2H6 used in the previous example were added.
It was introduced at a flow rate of 7 minutes CC and 10 CC 7 minutes. 8.6
P type a-
A 5i:H film was formed.

Next, a mixed gas of S i H4/H22 1/10]0
Add 0CC/min and energy -80.4KJ/g-5iH
4, a l-type a-3i:H film was formed for 25 minutes. Furthermore, the flow rate of the mixed waste used to form this one layer was set at 50 CC/m.
Introducing 10 CC/min of PH3/H2-0,1vo 1% mixed gas as in, n fj4 a-3i
: H film was formed. It took about 2 minutes to form the n-type a-3i:H film. The time required to form the p% "%" type a-Si film was 27 minutes and 30 seconds. Next, make AI true,
The photoelectric characteristics obtained by irradiating AMI light from the substrate 11+1, which was deposited by empty deposition and connected to the -th electrode, are Voc.
-0,87■, J5 (=14.2mA/cm", FF
= 0.62, and the efficiency was excellent at 7.65%. As described above, when SiH4 was used, excellent photoelectric conversion efficiency was obtained although the formation rate was slow.

As described above, the present invention does not use carbon or nitrogen.
The present invention provides a novel photoelectric conversion element formed with a window material and an excellent technology for its manufacturing method.

patent applicant Mitsui Toatsu Chemical Co., Ltd.

Claims (4)

[Claims] (1) In the pin type amorphous silicon photoelectric conversion element, (1) the upper Wep type amorphous silicon layer is composed of disilane and p
It is formed by glow discharge decomposition of a mixed scum consisting of a conductivity type imparting substance, and during the decomposition, the optical forbidden path of the p-type silicon layer is in the optical forbidden path of the i-type amorphous silicon layer. The p-type amorphous silicon layer has a wide optical forbidden path (11).
An amorphous silicon photoelectric conversion element characterized by being arranged at 1'+11. (2) The photoelectric conversion element according to claim 1, wherein Synlan and a p-type 4° C. type imparting substance are diluted and mixed with a diluent gas. (3) In the method for manufacturing a pin-type NRICON Kyudan conversion element, a gas mixture consisting of disilane and a p-type conductivity type imparting substance is introduced into a glow discharge chamber, and an energy of 10 KJ or less per unit mass of Ginran is applied to produce a glow discharge. decomposing to form a p-type amorphous silicon layer having a wider optical forbidden path than the optical forbidden path of the i-type amorphous silicon layer;
A method for manufacturing an amorphous silicon photoelectric conversion element, characterized in that the decomposition is performed so that the formed p-type silicon layer is formed on the light incident side. (4) The method for manufacturing a photoelectric conversion element according to claim 3, wherein the 7-norane and the p-type conductivity imparting substance are diluted and mixed with a diluent gas.