JP4256522B2 - Manufacturing method of silicon-based thin film photoelectric conversion device - Google Patents

Description

【００６３】
前記表１から明らかなようにリン原子の平均濃度が３×１０¹⁵ｃｍ^-3以上、５×１０¹⁶ｃｍ^-3以下である多結晶シリコン薄膜光電変換層を有する光電変換ユニットを備えた実施例１〜３の薄膜多結晶シリコン太陽電池は、リン原子の平均濃度が前記範囲を外れる多結晶シリコン薄膜光電変換層を有する光電変換ユニットを備えた比較例１，２の薄膜多結晶シリコン太陽電池に比べて優れた変換効率を有することがわかる。
【００６４】
【発明の効果】
以上詳述したように、本発明によれば低温プラズマＣＶＤ法により形成される高品質のシリコン系薄膜、並びにこのシリコン系薄膜からなる光電変換層を有する光電変換ユニットを備えた光電変換効率等の性能が向上されたシリコン系薄膜光電変換装置を提供できる。
【図面の簡単な説明】
【図１】本発明のシリコン系薄膜の成膜に用いられるプラズマＣＶＤ装置を示す概略図。
【図２】本発明に係わるシリコン系薄膜光電変換装置を模式的に示す斜視図。
【図３】二次イオン質量分析法により測定した、実施例１における多結晶シリコン薄膜光電変換層中のリン原子の深さ方向プロファイル。
【符号の説明】
１…反応容器、
２…排気管、
３…第１電極、
５…第２電極、
８，１０１…基板、
９…プラズマ、
１０２…Ｔｉ等の薄膜、
１０３…Ａｇ等の薄膜、
１０４…ＺｎＯ等の薄膜
１０５…一導電型半導体層、
１０６…結晶質シリコン系光電変換層、
１０７…逆導電型半導体層、
１０８…ＩＴＯ等の透明導電膜、
１１１…裏面電極、
１１２…結晶質シリコン系光電変換ユニット。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a silicon-based thin film photoelectric conversion device using a silicon thin film as a photoelectric conversion layer.
[0002]
In the specification of the present application, the terms “polycrystal” and “microcrystal” also mean those partially including an amorphous state.
[0003]
[Prior art]
In recent years, photoelectric conversion devices using thin films containing crystalline silicon, such as polycrystalline silicon and microcrystalline silicon thin films, have been vigorously developed. These developments are attempts to achieve both low cost and high performance of the photoelectric conversion device by forming a high-quality crystalline silicon thin film on an inexpensive substrate by a low-temperature process. Application to various photoelectric conversion devices such as is expected.
[0004]
As a method of forming a crystalline silicon thin film, for example, it is directly deposited on a substrate by a CVD method or a sputtering method, or an amorphous film is once deposited by a similar process, and then thermal annealing or laser annealing is performed. Methods such as crystallization are known. In any method, in order to use the above-described inexpensive substrate, it is necessary to carry out by a low temperature process.
[0005]
Among the above-mentioned film forming processes, the technique of directly depositing a crystalline silicon thin film by plasma CVD is the easiest to reduce the process temperature and increase the area of the thin film, and is a relatively simple process with high quality crystals. A thin film is expected to be obtained.
[0006]
When a polycrystalline silicon thin film is formed by plasma CVD, a high quality silicon thin film containing crystalline material is formed on a substrate in advance, and then the thin film is formed as a seed layer or a crystallization control layer on the substrate by plasma CVD. By forming a film, it is possible to form a high-quality polycrystalline silicon thin film at a relatively low temperature.
[0007]
On the other hand, in the plasma CVD method, a reaction gas obtained by diluting a silane-based source gas 10 times or more with hydrogen is introduced into a reaction vessel, and the inner pressure of the reaction vessel is set in a range of 10 mTorr to 1 Torr to form a film. It is well known that a silicon thin film can be obtained, and a microcrystalline silicon thin film can be easily formed even at a temperature of about 200 ° C.
[0008]
For example, Appl, Phys, Lett., Vol. 65, 1994, p.860 discloses a photoelectric conversion device including a photoelectric conversion unit made of a microcrystalline silicon pin junction. This photoelectric conversion unit is composed of a p-type semiconductor layer, an i-type semiconductor layer that is a photoelectric conversion layer, and an n-type semiconductor layer, which are sequentially stacked by a simple plasma CVD method. All of these semiconductor layers are microcrystalline silicon. It is.
[0009]
By the way, in the case of a silicon-based thin film that can be applied to a device such as a photoelectric conversion device, higher quality is required. In response to such demands, attempts have been made to reduce the amount of residual impurity atoms such as oxygen and carbon in the silicon thin film.
[0010]
[Problems to be solved by the invention]
However, there is a limit to reducing the concentration of residual impurity atoms in the silicon thin film, and the more the amount of any impurity that can be reduced, the more expensive the manufacturing apparatus and manufacturing line including the thin film forming apparatus are required. Therefore, there is a problem that the manufacturing cost is high. On the other hand, there are many unclear parts regarding the behavior of the above-described impurity atoms such as oxygen and carbon or impurity atoms such as phosphorus and boron which impart conductivity in the silicon-based photoelectric conversion layer in the thin-film silicon-based photoelectric conversion device.
[0011]
In view of the above-described problems of the prior art, the present invention provides a high-performance silicon provided with a high-quality silicon-based thin film formed by a low-temperature plasma CVD method and a photoelectric conversion unit having a photoelectric conversion layer made of this silicon-based thin film. An organic thin film photoelectric conversion device is to be provided.
[0012]
[Procedure for solving the problem]
As a result of repeated studies to solve the above-described problems, the present inventors have controlled the concentration of group V atoms such as phosphorus atoms within a specific range with respect to a silicon-based thin film applied to a photoelectric conversion device. It has been found that a high-performance silicon thin film photoelectric conversion device can be obtained.
[0014]
The method for producing a silicon-based thin film photoelectric conversion device according to the present invention includes an n-type silicon layer doped with 0.01 atomic% or more of phosphorus, a photoelectric conversion layer, and a p-type silicon layer formed by plasma CVD. In manufacturing a silicon-based thin film photoelectric conversion device equipped with a conversion unit,
The n-type silicon layer is set to a temperature of 150 to 300 ° C. by plasma CVD on the n-type silicon layer, and phosphorus is diffused into the silicon-based thin film being deposited using the n-type silicon layer as a phosphorus diffusion source. The above-mentioned silicon-based thin film comprising a substantially intrinsic semiconductor having an average phosphorus atom concentration of 3 × 10 ¹⁵ cm ⁻³ or more and 5 × 10 ¹⁶ cm ⁻³ or less and containing a crystalline material having a film thickness of 1.2 to 20 μm. A photoelectric conversion layer is formed .
[0015]
DETAILED DESCRIPTION OF THE INVENTION
The silicon-based thin film according to the present invention is a silicon-based thin film containing a crystal deposited using a plasma CVD method at a base temperature of 400 ° C. or less, and the average concentration of group V atoms in the thin film is 3 × 10 ^15. cm ⁻³ or more and 5 × 10 ¹⁶ cm ⁻³ or less.
[0016]
Examples of group V atoms in the silicon thin film include phosphorus and arsenic. The average concentration of the group V atoms is measured by, for example, secondary ion mass spectrometry (SIMS). In measurement of the group V atom concentration by SIMS, the range excluding the region in the depth direction of 0.5 μm or less from the surface of the thin film and the region in the depth direction of 0.5 μm or less from the surface in contact with the base is defined as the group V. It is preferable to use an average concentration measurement region of atoms.
[0017]
The aforementioned silicon-based thin film is formed by the following method using, for example, the plasma CVD apparatus shown in FIG.
[0018]
The rectangular reaction container 1 in FIG. 1 has exhaust pipes 2 and 2 that are exhaust members connected to opposite side walls. The other ends of the exhaust pipes 2 and 2 are connected to a vacuum device such as a mechanical booster pump and a dry pump (not shown). A valve (not shown) for taking in and out the substrate is provided on the opposite side wall of the reaction vessel 1.
[0019]
The rectangular first electrode 3 is arranged on the upper side in the reaction vessel 1 by being supported by a support shaft 4. A heater (not shown) for heating the substrate to be held is built in the lower portion of the first electrode 3. The first electrode 3 is connected to the ground, for example.
[0020]
The hollow second electrode 5 is disposed in the reaction container 1 so as to face the lower surface of the first electrode 3. A large number of gas blowing holes for blowing out reactive gas are formed in the surface (opposing surface) 6 of the second electrode 5 facing the first electrode 3. The second electrode 5 is connected to a power source (not shown) such as a high frequency power source. A gas introduction pipe 7 serving as a reaction gas introduction means is connected to the bottom of the second electrode 5 from the outside of the reaction vessel 1.
[0021]
In order to form a silicon-based thin film according to the present invention using the plasma CVD apparatus shown in FIG. 1, the substrate 8 is first held on the first electrode 3 in the reaction vessel 1 through a valve (not shown), and the first electrode 3 The film deposition portion of the substrate 8 is heated to 400 ° C. or less at which an inexpensive substrate such as glass can be used by heat generated by a heater (not shown) built in the substrate. A reaction gas containing a silane-based gas, hydrogen, and a desired amount of a group V element-containing compound gas is introduced into the hollow second electrode 5 through the introduction pipe 7, and the reaction gas is discharged from a number of gas blowing holes on the facing surface 6. At the same time as blowing toward the substrate 8 held by the first electrode 3, an exhaust device (not shown) is driven to exhaust the gas in the reaction vessel 1 through the exhaust pipes 2 and 2, and the inside of the reaction vessel 1 is predetermined. Hold at a vacuum level. Plasma 9 is generated in a region between the first and second electrodes 3 and 5 by applying, for example, high-frequency power to the second electrode 5 from a power source (not shown) while the degree of vacuum in the reaction vessel 1 is stable. Let When the plasma 9 is generated, the reaction gas is decomposed therein and silicon or the like is deposited on the surface of the substrate 8 heated to 400 ° C. or less, and the crystalline substance having the above-mentioned average concentration of the specific group V atoms is formed. A silicon thin film is formed.
[0022]
In such a film forming step, the specific group V atom concentration described above is controlled by controlling the amount of the group V element-containing compound gas in the reaction gas, the discharge power, the pressure in the reaction vessel, the temperature of the silicon deposition portion of the substrate, and the like. A silicon-based thin film is formed.
[0023]
In particular, when the silicon-based thin film is formed on a substrate whose underlying layer is a group V atom-doped semiconductor layer containing a group V atom as a conductive impurity, as described in a photoelectric conversion device described later, the group V atom-doped semiconductor is formed. By diffusing the layer as a group V atom introduction source (diffusion source) into the silicon-based thin film being deposited, the controllability and reproducibility of a small amount of group V atom concentration in the silicon-based thin film can be improved. When such an underlayer is used as a diffusion source, the temperature of the underlayer is preferably set to 150 to 300 ° C.
[0024]
In the film forming step, the flow rate of hydrogen, which is a dilution gas with respect to the silane-based gas in the total reaction gas, is preferably 20 times or more, but in combination with other film forming conditions (discharge power, reaction chamber pressure, etc.) The optimal dilution amount is determined by The amount of the group V element-containing compound gas is determined by the discharge power, the pressure in the reaction vessel, the temperature of the substrate, and the like.
[0025]
As the silane-based gas, for example, monosilane, disilane and the like are preferable, but in addition to these, a halogenated silicon gas such as silicon tetrafluoride, silicon tetrachloride, dichlorosilane may be used. In addition to such a silane-based gas, an inert gas such as hydrogen, nitrogen, or a rare gas, preferably helium, neon, argon, or the like may be used. As the group V element-containing compound gas, for example, phosphine (PH ₃ ), arsine (AsH ₃ ), or the like can be used.
[0026]
The plasma CVD apparatus used for forming the silicon-based thin film according to the present invention is not limited to the structure shown in FIG. For example, a plasma CVD apparatus having a structure in which the first electrode for holding the substrate and the second electrode for blowing out the reactive gas are reversed and the frequency is from 150 MHz or less to the VHF band and the microwave band is used as a power source is used. May be.
[0027]
The silicon-based thin film according to the present invention is polycrystalline silicon or microcrystalline silicon having a volume crystallization fraction of 80% or more, and is substantially an intrinsic semiconductor. However, since it is formed at a low temperature of 400 ° C. or less, it contains a large amount of hydrogen atoms for terminating and inactivating defects in the grain boundaries and grains, and the hydrogen content in the film is 1 atom% or more and 20 atoms. % Or less is preferable.
[0028]
In the silicon-based thin film according to the present invention, high quality can be achieved by setting the average concentration of group V atoms in the range of 3 × 10 ¹⁵ cm ⁻³ or more and 5 × 10 ¹⁶ cm ⁻³ or less.
[0029]
Next, a silicon-based thin film photoelectric conversion device according to the present invention will be described with reference to FIG. FIG. 2 is a perspective view schematically showing a silicon-based thin film photoelectric conversion device according to one embodiment of the present invention.
[0030]
The back electrode 111 is formed on the substrate 101.
[0031]
As the substrate 101, for example, a metal such as stainless steel, an organic film, an inexpensive glass having a low melting point, or the like can be used.
[0032]
The back electrode 110 includes, for example, metal thin films 102 and 103 including ITO, SnO ₂ , and a layer made of at least one metal selected from Ti, Cr, Al, Ag, Au, Cu, and Pt, or an alloy thereof. It is formed by laminating a transparent conductive thin film 104 combining layers made of at least one oxide selected from ZnO in this order. However, the back electrode 111 may be composed of a single metal thin film and a transparent conductive thin film, or only a metal thin film, or only a transparent conductive thin film. These thin films 102, 103, 104 are formed, for example, by vapor deposition or sputtering.
[0033]
On the back electrode 111, a photoelectric conversion unit 112 is formed, which is formed by sequentially laminating one conductive semiconductor layer 105, a crystalline silicon-based thin film photoelectric conversion layer 106, and a reverse conductive semiconductor layer 107 by plasma CVD. ing. The photoelectric conversion unit 112 is not limited to one unit, and a plurality of units may be formed on the back electrode 111.
[0034]
The one-conductivity-type semiconductor layer 105, the crystalline silicon-based thin film photoelectric conversion layer 106, and the reverse-conductivity-type semiconductor layer 107 will be described in detail below.
[0035]
1) One conductivity type semiconductor layer 105
The one-conductivity-type semiconductor layer 105 is, for example, an n-type silicon layer doped with phosphorus, which is a conductivity-determining impurity atom, by 0.01 atomic% or more, or a p-type silicon layer doped with 0.01 atomic% or more of boron. Can be used. However, these conditions regarding the one-conductivity type semiconductor layer 105 are not limited, and the impurity atom may be aluminum or the like in a p-type silicon layer, or an alloy material such as silicon carbide or silicon germanium may be used. Good.
[0036]
The one-conductivity-type silicon-based thin film 105 may be polycrystalline, microcrystalline, or amorphous, and the film thickness is preferably 1 to 100 nm, more preferably 2 to 30 nm.
[0037]
2) Crystalline silicon-based thin film photoelectric conversion layer 106
This crystalline silicon-based thin film photoelectric conversion layer 106 has an average concentration of group V atoms such as phosphorus and arsenic of 3 × 10 ¹⁵ cm ⁻³ or more deposited at a base temperature of 400 ° C. or lower using a plasma CVD method. It is made of a silicon-based thin film containing a crystalline material which is 5 × 10 ¹⁶ cm ⁻³ or less and is substantially an intrinsic semiconductor. The photoelectric conversion layer 106 is set to have a film thickness of 1.2 to 20 μm.
[0038]
The photoelectric conversion layer 106 preferably has a structure in which most of the crystal grains contained therein are grown in a columnar shape upward from the one-conductive semiconductor layer (underlayer) 105. Many of these crystal grains have a (110) preferential crystal orientation plane parallel to the film surface, and the intensity ratio of the (111) diffraction peak to the (220) diffraction peak determined by X-ray diffraction is 1/5. Below, it is desirable that it is 1/10 or less.
[0039]
Even when the surface shape of the one conductivity type layer 105 as a base layer is substantially flat, the photoelectric conversion layer 106 is finely spaced on the surface after the film formation described above by about one digit smaller than the film thickness. The surface texture structure having various irregularities is allowed to be formed.
[0040]
3) Reverse conductivity type semiconductor layer 107
As the reverse conductivity type semiconductor layer 107, for example, a p-type silicon thin film doped with boron, which is a conductivity type determining impurity atom, 0.01 atomic% or more, or an n-type silicon thin film doped with phosphorus 0.01 atomic% or more. Etc. can be used. However, these conditions for the reverse conductivity type semiconductor layer 107 are not limited. As the impurity atoms, for example, aluminum may be used in p-type silicon, or a film of an alloy material such as silicon carbide or silicon germanium may be used. This reverse conductive electrode silicon thin film 107 may be polycrystalline, microcrystalline, or amorphous, and its film thickness is set within a range of 3 to 100 nm, more preferably within a range of 5 to 50 nm. The
[0041]
The transparent conductive oxide film 108 is formed on the photoelectric conversion unit 112. The comb-shaped metal electrode 109 is formed on the transparent conductive oxide film 108.
[0042]
The transparent conductive oxide film 108 is formed of at least one layer selected from, for example, ITO, SnO ₂ , ZnO or the like.
[0043]
The comb-shaped metal electrode 109 (grid electrode) is formed by patterning a layer of at least one metal selected from Al, Ag, Au, Cu, Pt, or the like, or an alloy thereof. These metal or alloy layers are formed by sputtering or vapor deposition, for example.
[0044]
In the photoelectric conversion device having such a structure, the light 110 is incident on the transparent conductive oxide film 108 and subjected to photoelectric conversion, and is output from, for example, between the terminals of the metal thin film 103 and the metal electrode 109 of the back electrode 111. .
[0045]
FIG. 2 only illustrates one of the silicon-based thin film photoelectric conversion devices, and the present invention is added to at least one crystal-based thin film photoelectric conversion unit including the silicon crystalline photoelectric conversion layer shown in FIG. Thus, the present invention can also be applied to a tandem photoelectric conversion device including at least one other amorphous thin film photoelectric conversion unit including an amorphous photoelectric conversion layer formed by a known method.
[0046]
【Example】
Hereinafter, preferred embodiments of the present invention will be described in detail in comparison with comparative examples.
[0047]
Example 1
Similar to the embodiment of FIG. 2 described above, a crystalline silicon thin film solar cell as Example 1 was manufactured.
[0048]
On the glass substrate 101, first, a Ti film 102, an Ag film 103, a ZnO film 104, and a ZnO film 104, respectively, were formed as the back base electrode 111 by sputtering. Next, the phosphorus-doped n-type silicon layer 105 is 10 nm, the substantially intrinsic semiconductor photoelectric conversion layer 106 is 4 μm, and the p-type silicon layer 107 is 10 nm, respectively, and includes a nip junction crystalline material. A silicon-based photoelectric conversion unit 112 was formed. Further, a transparent conductive film ITO 108 having a thickness of 80 nm and a comb-shaped Ag electrode 109 for taking out current were formed as upper electrodes.
[0049]
Here, the polycrystalline silicon thin film photoelectric conversion layer 106 holds the glass substrate after the phosphorus-doped n-type silicon layer is formed on the first electrode 3 of the reaction vessel 1 shown in FIG. The first and second electrodes 3 and 5 were deposited by an RF plasma CVD method for generating plasma.
[0050]
・ Back pressure before film formation: 2 × 10 ⁻³ Torr
-Reactive gas blown out from the second electrode 5; flow rate ratio of silane and hydrogen 1:90, phosphine 0.5 ppm,
-Pressure in the reaction vessel; 5.0 Torr,
Power applied to the second electrode 5; high frequency power of 13.56 MHz,
-Discharge power density: 100 mW / cm ²
-Substrate underlayer temperature: 200 ° C.
[0051]
The obtained polycrystalline silicon thin film photoelectric conversion layer 106 had a deposited crystallization fraction of 92% and a hydrogen content of 7.5 atomic%. Further, this polycrystalline silicon thin film photoelectric conversion layer 106 had a ratio of (111) diffraction peak to (220) diffraction peak obtained by X-ray diffraction spectrum was 0.14.
[0052]
Further, the phosphorus atom concentration in the polycrystalline silicon thin film photoelectric conversion layer 106 was determined by secondary ion mass spectrometry (SIMS). The result is shown in FIG. FIG. 3 shows the depth direction distribution of phosphorus concentration in the photoelectric conversion layer, the vertical axis indicates the concentration of phosphorus atoms, and d in the horizontal axis indicates the depth of the photoelectric conversion layer. FIG. 3 shows that the average concentration of phosphorus atoms in the photoelectric conversion layer is 5 × 10 ¹⁵ cm ⁻³ . In FIG. 3, the region having a high phosphorus concentration appears on the front surface layer and the back surface layer (on the n-type silicon layer 105 side) due to a problem in SIMS measurement.
[0053]
(Example 2)
A solar cell was manufactured under the same conditions as in Example 1 except that the plasma CVD conditions for the photoelectric conversion layer 106 were partially changed.
[0054]
That is, in Example 2, the substrate underlayer temperature was changed to 150 ° C. The photoelectric conversion layer 106 formed under such partially changed conditions had a deposition crystallization fraction of 80% and a hydrogen content of 12 atomic%. Further, this polycrystalline silicon thin film photoelectric conversion layer 106 had a ratio of the (111) diffraction peak to the (220) diffraction peak determined by the X-ray diffraction spectrum was 0.2. Furthermore, the average concentration of phosphorus atoms in the polycrystalline silicon thin film photoelectric conversion layer 106 determined by secondary ion mass spectrometry (SIMS) was 3 × 10 ¹⁵ cm ⁻³ .
[0055]
(Example 3)
A solar cell was manufactured under the same conditions as in Example 1 except that the plasma CVD conditions for the photoelectric conversion layer 106 were partially changed.
[0056]
That is, in Example 3, the substrate underlayer temperature was changed to 300 ° C. The photoelectric conversion layer 106 formed under such partially changed conditions had a deposition crystallization fraction of 96% and a hydrogen content of 4.5 atomic%. Further, this polycrystalline silicon thin film photoelectric conversion layer 106 had a ratio of the (111) diffraction peak to the (220) diffraction peak determined by the X-ray diffraction spectrum was 0.09. Furthermore, the average concentration of phosphorus atoms in the polycrystalline silicon thin film photoelectric conversion layer 106 obtained by secondary ion mass spectrometry (SIMS) was 5 × 10 ¹⁶ cm ⁻³ .
[0057]
(Comparative Example 1)
A solar cell was manufactured under the same conditions as in Example 1 except that the plasma CVD conditions for the photoelectric conversion layer 106 were partially changed.
[0058]
That is, in Comparative Example 1, the substrate underlayer temperature was changed to 100 ° C. The photoelectric conversion layer 106 formed under such partially changed conditions had a deposited crystallization fraction of 65% and a hydrogen content of 21 atomic%. Further, this polycrystalline silicon thin film photoelectric conversion layer 106 had a ratio of (111) diffraction peak to (220) diffraction peak obtained by X-ray diffraction spectrum was 0.46. Furthermore, the average concentration of phosphorus atoms in the polycrystalline silicon thin film photoelectric conversion layer 106 obtained by secondary ion mass spectrometry (SIMS) was 2 × 10 ¹⁵ cm ⁻³ .
[0059]
(Comparative Example 2)
A solar cell was manufactured under the same conditions as in Example 1 except that the plasma CVD conditions for the photoelectric conversion layer 106 were partially changed.
[0060]
That is, in Comparative Example 2, the substrate underlayer temperature was changed to 400 ° C. The photoelectric conversion layer 106 formed under such partially changed conditions had a deposition crystallization fraction of 98% and a hydrogen content of 0.98 atomic%. Further, this polycrystalline silicon thin film photoelectric conversion layer 106 had a ratio of (111) diffraction peak to (220) diffraction peak obtained by X-ray diffraction spectrum was 0.16. Furthermore, the average concentration of phosphorus atoms in the polycrystalline silicon thin film photoelectric conversion layer 106 obtained by secondary ion mass spectrometry (SIMS) was 1.5 × 10 ¹⁷ cm ⁻³ .
[0061]
The conversion efficiencies when the light amounts of AM 1.5 and 100 mW / cm ² were used as the incident light 110 in the thin film polycrystalline silicon solar cells of Examples 1 to 3 and Comparative Examples 1 and 2 obtained were examined. The results are shown in Table 1 below.
[0062]
[Table 1]

[0063]
As is apparent from Table 1, an embodiment provided with a photoelectric conversion unit having a polycrystalline silicon thin film photoelectric conversion layer having an average concentration of phosphorus atoms of 3 × 10 ¹⁵ cm ⁻³ or more and 5 × 10 ¹⁶ cm ⁻³ or less. The thin film polycrystalline silicon solar cells 1 to 3 are the thin film polycrystalline silicon solar cells of Comparative Examples 1 and 2 including a photoelectric conversion unit having a polycrystalline silicon thin film photoelectric conversion layer in which the average concentration of phosphorus atoms is outside the above range. It turns out that it has the conversion efficiency outstanding compared with.
[0064]
【The invention's effect】
As described above in detail, according to the present invention, a high-quality silicon-based thin film formed by a low-temperature plasma CVD method, and a photoelectric conversion efficiency including a photoelectric conversion unit having a photoelectric conversion layer made of this silicon-based thin film A silicon-based thin film photoelectric conversion device with improved performance can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a plasma CVD apparatus used for forming a silicon-based thin film of the present invention.
FIG. 2 is a perspective view schematically showing a silicon-based thin film photoelectric conversion device according to the present invention.
FIG. 3 is a profile in the depth direction of phosphorus atoms in the polycrystalline silicon thin film photoelectric conversion layer in Example 1 measured by secondary ion mass spectrometry.
[Explanation of symbols]
1 ... reaction vessel,
2 ... exhaust pipe,
3 ... 1st electrode,
5 ... second electrode,
8, 101 ... substrate,
9 ... Plasma,
102 ... a thin film such as Ti,
103 ... A thin film such as Ag,
104 ... Thin film 105 such as ZnO ... One conductivity type semiconductor layer,
106 ... crystalline silicon photoelectric conversion layer,
107 ... reverse conductivity type semiconductor layer,
108 ... Transparent conductive film such as ITO,
111 ... back electrode,
112 ... A crystalline silicon photoelectric conversion unit.

Claims (2)

In manufacturing a silicon-based thin film photoelectric conversion device including a photoelectric conversion unit in which an n-type silicon layer doped with 0.01 atomic% or more of phosphorus, a photoelectric conversion layer, and a p-type silicon layer are formed by plasma CVD. ,
The n-type silicon layer is set to a temperature of 150 to 300 ° C. by plasma CVD on the n-type silicon layer, and phosphorus is diffused into the silicon-based thin film being deposited using the n-type silicon layer as a phosphorus diffusion source. The above-mentioned silicon-based thin film comprising a substantially intrinsic semiconductor having an average phosphorus atom concentration of 3 × 10 ¹⁵ cm ⁻³ or more and 5 × 10 ¹⁶ cm ⁻³ or less and containing a crystalline material having a film thickness of 1.2 to 20 μm. A method for producing a silicon-based thin film photoelectric conversion device, comprising forming a photoelectric conversion layer . The crystalline silicon-containing thin film is made of polycrystalline silicon or microcrystalline silicon having a volume crystallization fraction of 80% or more, and has a hydrogen content of 1 atomic% or more and 20 atomic% or less, and further in the thickness direction. 2. The crystal orientation of (110) as a dominant orientation plane, and the ratio of (111) diffraction peak to (220) diffraction peak in an X-ray diffraction spectrum is 0.2 or less. Manufacturing method of silicon-based thin film photoelectric conversion device .

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