CN115548145A - Method for improving photoelectric conversion efficiency of GaAs thin-film solar cell - Google Patents
Method for improving photoelectric conversion efficiency of GaAs thin-film solar cell Download PDFInfo
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- CN115548145A CN115548145A CN202211211066.6A CN202211211066A CN115548145A CN 115548145 A CN115548145 A CN 115548145A CN 202211211066 A CN202211211066 A CN 202211211066A CN 115548145 A CN115548145 A CN 115548145A
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- 229910001218 Gallium arsenide Inorganic materials 0.000 title claims abstract description 30
- 238000006243 chemical reaction Methods 0.000 title claims abstract description 15
- 238000000034 method Methods 0.000 title claims abstract description 15
- 239000010409 thin film Substances 0.000 title claims description 17
- 238000010521 absorption reaction Methods 0.000 claims abstract description 15
- 238000005452 bending Methods 0.000 claims abstract description 4
- 239000010410 layer Substances 0.000 claims description 75
- 239000010408 film Substances 0.000 claims description 18
- 239000004065 semiconductor Substances 0.000 claims description 8
- 239000000463 material Substances 0.000 claims description 7
- 230000003667 anti-reflective effect Effects 0.000 claims description 4
- 239000003989 dielectric material Substances 0.000 claims description 4
- 239000004038 photonic crystal Substances 0.000 claims description 3
- 239000002356 single layer Substances 0.000 claims description 3
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 2
- 238000005215 recombination Methods 0.000 abstract description 11
- 230000006798 recombination Effects 0.000 abstract description 11
- 239000000969 carrier Substances 0.000 abstract description 9
- 150000001875 compounds Chemical class 0.000 description 5
- 230000004888 barrier function Effects 0.000 description 3
- 239000000758 substrate Substances 0.000 description 3
- 239000002344 surface layer Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000002161 passivation Methods 0.000 description 2
- 238000005036 potential barrier Methods 0.000 description 2
- 229910000980 Aluminium gallium arsenide Inorganic materials 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- 229910010413 TiO 2 Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 238000004347 surface barrier Methods 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/0248—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies
- H01L31/0256—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by the material
- H01L31/0264—Inorganic materials
- H01L31/0304—Inorganic materials including, apart from doping materials or other impurities, only AIIIBV compounds
- H01L31/03046—Inorganic materials including, apart from doping materials or other impurities, only AIIIBV compounds including ternary or quaternary compounds, e.g. GaAlAs, InGaAs, InGaAsP
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/02—Details
- H01L31/0216—Coatings
- H01L31/02161—Coatings for devices characterised by at least one potential jump barrier or surface barrier
- H01L31/02167—Coatings for devices characterised by at least one potential jump barrier or surface barrier for solar cells
- H01L31/02168—Coatings for devices characterised by at least one potential jump barrier or surface barrier for solar cells the coatings being antireflective or having enhancing optical properties for the solar cells
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
- H01L31/06—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers
- H01L31/062—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers the potential barriers being only of the metal-insulator-semiconductor type
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/544—Solar cells from Group III-V materials
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- Power Engineering (AREA)
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Abstract
The invention discloses a method for improving the photoelectric conversion efficiency of a GaAs film solar cell, which takes a window layer as an active layer of the solar cell, introduces fixed charges into an antireflection structure, generates induced charges on the outer surface of the window layer, generates energy band bending near the surface and prevents minority carrier from flowing to the surface to be compounded. The structure increases the absorption efficiency of short-wave photons on one hand, and reduces the surface recombination of minority carriers on the other hand, thereby improving the collection efficiency of the minority carriers and improving the short-circuit current and the conversion efficiency.
Description
Technical Field
The invention relates to the technical field of III-V cluster compound semiconductor solar cells, in particular to a method for improving photoelectric conversion efficiency of a GaAs thin film solar cell.
Background
The III-V cluster compound semiconductor material is widely applied to solar cells due to the advantages of high carrier mobility, direct band gap and the like. However due to IIThe I-V cluster compound has high surface recombination rate, and a thin Al layer is often made on the surface of the battery in order to reduce the surface recombination 0.8 Ga 0.2 As window layer (typically less than 100 nm). Taking the GaAs material as an example, the purpose is: on the one hand, due to Al 0.8 Ga 0.2 As and GaAs have very good lattice matching, and the surface recombination rate of the GaAs material can be obviously reduced. On the other hand, al 0.8 Ga 0.2 As has a wider band gap width, only short-wave photons with energy larger than the band gap width are absorbed, most of the photons can penetrate through the window layer to enter the GaAs active layer, and therefore only a few photon-generated carriers are generated in the window layer.
Although the window layer can reduce the GaAs surface recombination rate, most short-wave photons cannot be absorbed and are lost due to the low absorption efficiency of the GaAs material to short waves; on the other hand despite Al 0.8 Ga 0.2 As has a wider band gap, but still cannot avoid photons being absorbed at the window layer and carriers being generated, but this portion of carriers is recombined due to the high surface recombination rate of AlGaAs, resulting in a recombination current. The existing problems can be solved from two aspects: on one hand, the Al component can be adjusted to obtain a proper forbidden band width, the thickness of the window layer is increased, the absorption efficiency of short-wave photons on the window layer is enhanced, and the utilization rate of sunlight is improved; on the other hand, in order to improve the carrier collection efficiency in the window layer, the recombination rate of surface carriers needs to be reduced.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a method for improving the photoelectric conversion efficiency of a GaAs thin film solar cell.
The technical scheme of the invention is as follows:
a method for improving the photoelectric conversion efficiency of a GaAs thin film solar cell comprises the following steps:
1) The window layer is used as a photon absorption layer to enhance the absorption efficiency of short-wave photons;
2) Adjusting the Al component of the window layer to obtain a proper forbidden band width;
3) The thickness of the window layer is increased, and the absorption efficiency of short-wave photons in the window layer is enhanced;
4) The MIS solar cell structure is constructed, namely, the antireflection film and the window layer are separated by an insulating layer,
5) Fixed charges are introduced into the antireflection film, so that induced charges are generated on the surface of the window layer, and energy band bending is caused.
Further, the window layer adopts Al x Ga 1-x An As material, wherein x =0.3-0.4; other materials for the window layer of the solar cell can also be adopted for the window layer;
furthermore, the antireflection film adopts a single-layer dielectric material film or a double-layer dielectric material film or a photonic crystal array structure; such as a single layer of SiO 2 /TiO 2 /Si 3 N 4 Equal or double-layer antireflection film MF 2 ZnS, or the like, or a dielectric photonic crystal array structure, or the like;
further, the fixed charges, including negative charges or positive charges, are introduced into the antireflection film.
Further, the MIS solar cell structure means that the metal and the semiconductor/antireflection film are separated by an insulator;
further, the window layer is a semiconductor window layer.
Further, the insulating layer adopts Al 2 O 3 。
Further, by varying the fixed charge (N) in the anti-reflective film fix ) The concentration, thereby changing the surface induced charge concentration of the window layer, causing the surface barrier height to change.
The invention has the following beneficial effects:
1) The invention uses Al 0.4 Ga 0.6 As is used As a part of an active layer of the solar cell, the active layer has a strong absorption effect on solar short-wave photons, and due to the existence of a potential barrier, photon-generated minority carriers in the region can be collected by a PN junction, so that the photon-generated current of the solar cell is improved.
2) By increasing the concentration of the fixed charges, the recombination rate of the surface of the window layer can be close to zero, and a surface passivation process is not needed.
3) Compared with the traditional solar cell, the short-circuit electric current is obviously higher, so that the conversion efficiency is higher.
4) The method is not only suitable for GaAs solar cells, but also suitable for III-V cluster compound semiconductor solar cell structures with window layers as passivation layers of active absorption layers.
Drawings
FIG. 1 is a schematic structural diagram of an embodiment of the present invention;
FIG. 2 is a schematic diagram of the barrier heights corresponding to different fixed charges according to the present invention;
FIG. 3 is a graph comparing J-V curves for AM1.5 surface solar spectrum normal incidence for MIS structures of the present invention corresponding to different fixed charges;
in the figure: 1. a GaAs active layer; 2. al (Al) 0.4 Ga 0.6 An As window layer; 3. al (Al) 0.3 Ga 0.7 An As back surface layer; 4. al (Al) 2 O 3 An insulating layer; 5. a ZnS thin film layer; 6. MgF 2 A thin film layer; 7. a GaAs substrate; 8. a positive electrode; 9. a back electrode.
Detailed Description
The invention is further explained below with reference to the drawings and examples.
A method for improving the photoelectric conversion efficiency of a GaAs thin film solar cell adopts a novel MIS solar cell structure (namely metal/insulating layer/semiconductor), obtains the forbidden bandwidth of a proper window layer by adjusting Al components, and enhances the absorption of short-wave photons; meanwhile, fixed charges are introduced into the antireflection film, so that induced charges are generated on the surface of the window layer, energy band bending is caused, minority carriers are prevented from flowing to the surface, the surface recombination rate is reduced, and the collection efficiency of the minority carriers is improved. The concept is not only suitable for GaAs solar cells, but also has very good effect on III-V cluster compound semiconductor solar cells with high surface recombination rate.
The embodiment is as follows:
novel MI-Al 0.4 Ga 0.6 As/GaAs/Al 0.3 Ga 0.7 As solar cell structure, as shown in FIG. 1, the solar cell is composed of GaAs absorption layer (GaAs active layer 1) and Al 0.4 Ga 0.6 As absorption layer (Al) 0.4 Ga 0.6 As window layer 2) together form the active layer of the solar cell and Al 0.3 Ga 0.7 As Back surface layer 3, al 2 O 3 Insulating layer 4, double-layer antireflection layer ZnS thin film layer 5 and MgF 2 A film layer 6, a GaAs substrate 7, a positive electrode 8 and a back electrode 9.
In this embodiment, the induced barrier height of the window layer is varied by varying the fixed charge concentration within the anti-reflective layer;
as shown in FIG. 1, n-Al 0.4 Ga 0.6 The thickness of the As absorption layer is 50nm (the doping concentration is N) D ＝1×10 18 cm -3 ) N-GaAs emitter region thickness of 50nm (N) D ＝2×10 18 cm -3 ) The thickness of the p-GaAs base region is 150nm (N) A ＝1×10 17 cm -3 )，N A Representing the doping concentration of the P region; the back surface layer is n-Al with a thickness of 100nm 0.3 Ga 0.7 As layer (NA =1 × 10) 18 cm -3 ) ZnS thin film layer 5 and MgF 2 The thin film layer 6 (double-layer antireflection film) is 100nm and 50nm respectively 2 O 3 The thickness of the insulating layer 4 is 10nm, the thickness of the positive electrode 8 and the back electrode 9 is 200nm, the thickness of the GaAs substrate 7 is 3000nm, and the thickness of the silver (Ag) is 200nm.
In the embodiment, the window layer is an n-type region, so that fixed charges in the antireflection layer are positive charges, and potential barriers on the surface of the window layer are bent downwards to prevent minority carrier electrons from moving to the surface, so that the collection efficiency of the minority carrier is enhanced; the higher the fixed charge concentration is, the higher the barrier height is, and the stronger the reflection to the carrier is; as shown in fig. 2, the higher the fixed charge concentration is, the more the band bends downward, and the stronger the blocking effect on minority carrier holes is.
The above-mentioned embodiments are only for illustrating the present invention, not for limiting the scope of the present invention, and all structural changes made without inventive work from the conception of the present invention fall within the scope of the present invention.
Claims (6)
1. A method for improving the photoelectric conversion efficiency of a GaAs thin film solar cell is characterized by comprising the following steps:
1) The window layer is used as a photon absorption layer to enhance the absorption efficiency of short-wave photons;
2) Adjusting the Al component of the window layer to obtain a proper forbidden bandwidth;
3) The thickness of the window layer is increased, and the absorption efficiency of short-wave photons in the window layer is enhanced;
4) Constructing an MIS solar cell structure, namely, separating the antireflection film and the window layer by using an insulating layer;
5) Fixed charges are introduced into the antireflection film, so that induced charges are generated on the surface of the window layer, and energy band bending is caused.
2. The method for improving the photoelectric conversion efficiency of the GaAs thin film solar cell as claimed in claim 1, wherein Al is used for the window layer x Ga 1-x As material, wherein x =0.3-0.4.
3. The method for improving the photoelectric conversion efficiency of the GaAs thin film solar cell as claimed in claim 1, wherein the anti-reflective film is a single layer dielectric material film or a double layer dielectric material film or a photonic crystal array structure.
4. The method for improving the photoelectric conversion efficiency of the GaAs thin film solar cell as claimed in claim 1, wherein a fixed charge comprising a negative charge or a positive charge is introduced into the anti-reflective film.
5. The method for improving the photoelectric conversion efficiency of the GaAs thin film solar cell as claimed in claim 1, wherein the window layer is a semiconductor window layer.
6. The method for improving the photoelectric conversion efficiency of the GaAs thin-film solar cell as claimed in claim 1, wherein the insulating layer is made of Al 2 O 3 。
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211211066.6A CN115548145A (en) | 2022-09-30 | 2022-09-30 | Method for improving photoelectric conversion efficiency of GaAs thin-film solar cell |
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| CN202211211066.6A CN115548145A (en) | 2022-09-30 | 2022-09-30 | Method for improving photoelectric conversion efficiency of GaAs thin-film solar cell |
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