WO2008010205A2 - Dispositif de conversion photovoltaïque à couche mince et son procédé de fabrication - Google Patents

Dispositif de conversion photovoltaïque à couche mince et son procédé de fabrication Download PDF

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Publication number
WO2008010205A2
WO2008010205A2 PCT/IL2007/000847 IL2007000847W WO2008010205A2 WO 2008010205 A2 WO2008010205 A2 WO 2008010205A2 IL 2007000847 W IL2007000847 W IL 2007000847W WO 2008010205 A2 WO2008010205 A2 WO 2008010205A2
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layer
substrate
band gap
gas mixture
seem
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PCT/IL2007/000847
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WO2008010205A3 (fr
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Boris Sigalov
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Solaroll Ltd
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Publication of WO2008010205A3 publication Critical patent/WO2008010205A3/fr

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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
    • H01L31/065—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 graded gap type
    • 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

Definitions

  • the present invention relates to thin-film photovoltaic (photoelectric) conversion devices and to a method of their manufacturing, more particularly, to a method of manufacturing which can provide the performance of a conversion device, reduce its cost, enhance the flexibility of manufacturing steps and improve manufacturing efficiency.
  • a silicon thin film photovoltaic conversion device includes a first electrode, one or more semiconductor thin film photovoltaic conversion units and a second electrode stacked in sequence on a substrate at least a surface portion of which is insulated. Further, one photoelectric conversion unit includes an i-type layer sandwiched between a p-type and an n-type layer.
  • i-type layer as a photovoltaic conversion layer has a greater thickness for the purpose of light absorption, though increase of the thickness increases costs and time for deposition of the i-type layer.
  • the p-type and n-type conductive layers serve to produce a diffusion potential within the photovoltaic conversion unit, and magnitude of the diffusion potential affects the value of open-circuit voltage which is one of the important properties of a thin photovoltaic conversion device.
  • these conductive layers are inactive layers, which do not directly contribute to photovoltaic conversion. That is, light absorbed by these inactive layers is a loss, which does not contribute to electric power generation. Consequently, it is preferable to minimize the thickness of the p-type and n-type conductive layers as far as they provide a sufficient diffusion potential.
  • European patent application EP 1198013 A2 by "Kaneka Corporation" (Japan) describes a solar cell including a plurality of photoelectric conversion units stacked on a substrate, each having a p-type layer, an i-type photoelectric conversion layer and an n-type layer deposited in this order from a light-incident side of the solar cell, and at least a rear unit among the photoelectric conversion units that is furthest from the light-incident side being a crystalline unit including a crystalline i-type photoelectric conversion layer.
  • Manufacturing method includes the steps of forming at least one of the units on a substrate by plasma CVD and immediately thereafter forming an i-type boundary layer to a thickness of at most 5 nm by plasma CVD, and thereafter removing the substrate into the atmosphere and then forming a crystalline unit on the i-type boundary layer by plasma CVD.
  • patent application 2005/0181534 Al describe a method of manufacturing a tandem-type thin film photoelectric conversion device including the steps of forming at least one photoelectric conversion unit on a substrate in a deposition apparatus, taking out the substrate having the photoelectric conversion unit from the deposition apparatus to the air, introducing the substrate into a deposition apparatus and carrying out plasma exposure processing on the substrate in an atmosphere of a gas mixture containing an impurity for determining the conductivity type of the same, as the uppermost conductivity type intermediate layer is formed by additionally supplying semiconductor raw gas to the deposition apparatus, and then forming a subsequent photoelectric conversion unit.
  • the two solar cells described above differ in composition and structure of their i-layer. It is known that the i-layer is a basic layer in solar cells absorbing sunlight, in this case it is an i-layer of amorphous silicon a-Si:H generating electrons and holes.
  • the forbidden energy gap in described solar cells measures about 1.7 eV. This means that sunlight having a smaller energy (Eg) than the forbidden energy gap will not be absorbed by such solar cells.
  • Eg energy
  • Doping the silicon which forms the i-layer of a solar cell by germanium allows to lower the energy threshold Eg to 1.5 - 1.6 eV.
  • Another way of lowering the threshold of absorbed energy Eg is the use of such tandem (cascade) solar cells wherein each p-i-n unit absorbs its range of the solar spectrum.
  • a thin-film solar cell which comprises an a ⁇ SiGe:H (1.6 eV) p-i-n solar cell having a deposition rate of at least ten (10) A°/second for the a- SiGe:H intrinsic layer by hot wire chemical vapor deposition.
  • a method for fabricating a thin film solar cell comprises depositing a p-i-n layer at a deposition rate of at least ten (10) A°/second for the a-SiGe:H intrinsic layer.
  • a stacked photovoltaic device comprises at least three p-i-n junction constituent devices superposed in layers, each having a p-type layer, an i- type layer and an n-type layer which are formed of silicon type non-single-crystal semiconductors.
  • An amorphous silicon layer is used as the i-type layer of a first p- i-n junction
  • a microcrystalline silicon layer is used as the i-type layer of a second p-i-n junction
  • a microcrystalline silicon layer is used as the i-type layer of a third p-i-n junction, the first to third layers being in order from the light-incident side.
  • the drawbacks of these solar cells are a small forbidden energy gap which ranges from 1.55 to 1.75 eV, and voltage loss in each layer of the p-i-n structure.
  • U.S. Pat. 6,723,421 describes a non-single semiconductor material including coordinatively irregular structures characterized by distorted chemical bonding, reduced dimensionality and novel electronic properties.
  • a process for forming the material permits variation of size, concentration and spatial distribution of coordinatively irregular structures.
  • the electronic properties of the material can be changed by controlling the characteristics of the coordinatively irregular structures.
  • Aforementioned patent applications U.S. 2004/0231590 Al and U.S.2006/0024442 Al by Stanford R. Ovshinsky describe a deposition apparatus and method for continuously depositing a polycrystalline material such as polysilicon or polycrystalline SiGe-layer on a mobile discrete or continuous web substrate.
  • the apparatus includes a pay-out unit door dispensing a discrete or continuous web substrate and a deposition unit that receives the discrete or continuous web substrate and deposits a series of one or more thin film layers thereon in a series of one or more deposition or processing chambers.
  • polysilicon is formed by first depositing a layer of amorphous or macOcrystalline silicon using PECVD and transforming this layer to polysilicon through heating or annealing with one or more lasers, lamps, furnaces or other heat sources. Laser annealing utilizing a pulsed exciter is a preferred embodiment.
  • the instant deposition apparatus affords control over the grain size of polysilicon. Passivation of polysilicon occurs through treatment with a hydrogen plasma. Layers of polycrystalline SiGe may be formed likewise.
  • the instant deposition apparatus provides for continuous deposition of electronic devices and structures that include a layer of a polycrystalline material such as polysilicon and/or polycrystalline SiGe. Representative devices include photovoltaic devices and thin film transistors.
  • the instant deposition apparatus also provides for continuous deposition of chalcogenide switching or memory materials alone or in combination with another metal, insulating, and/or semiconducting layers.
  • a thin-film photovoltaic conversion device is formed of a substrate; a first conductive layer; a first doped layer; a graded (varizone) band gap layer having two side faces and including pure silicon and silicon in chemical compositions with germanium, carbon, nitrogen, or nitrogen and oxygen, of the formula selected from a group, consisting of Si x Ge 1-X , Si x Cy, Si x Ny, and Si x OyN 2 , all these chemical compositions being simultaneously comprised in graded band gap layer, and disposed successively in direction from one said side face to the other and smoothly changing from one to the other; a second doped layer; and a second conductive layer.
  • the substrate of this conversion device is made of metal, glass or plastic and a graded band gap layer mainly comprising silicone.
  • the thin-film photovoltaic conversion device additionally comprises a reflective layer near the substrate on a light-incident substrate side, an anti-reflective layer disposed above said layers on the light-incident side of the device, and a protective laminating layer disposed on the photovoltaic conversion device on the side opposite to the substrate.
  • the substrate of the thin-film photovoltaic conversion device is made of flexible plastic.
  • the first conductive layer and the second conductive layer are electrodes.
  • the first conductive layer or the second conductive layer, disposed on the light-incident side relative to the substrate, is transparent .
  • the first doped layer and second doped layer are disposed on both sides of the graded band gap layer, one of them being of a p-type, and the other of an n-type.
  • the band gap layer has two side faces and includes pure silicon and silicon in chemical compositions with germanium, carbon, nitrogen, or nitrogen and oxygen, of the formula selected from a group, consisting of Si x Ge 1-X , Si x Cy, Si x Ny, and Si x O y N z .
  • Chemical composition of the graded band gap layer is smoothly transitioning in sequence: Si x Ge 1-X , Si, Si x Cy, Si x Ny, Si x OyN 2 , in a light direction. Energetic limits of the chemical compositions comprised in this graded band gap layer change from 0,9 eV (infrared region) to 3,5 eV (ultra-violet region).
  • this device is made by sequentially forming on a substrate a first conductive layer; a first doped layer; a graded band gap layer including pure silicon and silicon in chemical compositions with germanium, carbon, nitrogen, or nitrogen and oxygen, of the formula selected from the group consisting of Si x Ge 1-X , Si x Cy, Si x Ny, and Si x O y N z ; a second doped layer and a second conductive layer.
  • a thin-film photovoltaic conversion device is made by additionally forming a reflective layer disposed near said substrate on a light-incident substrate-side, an anti-reflective layer disposed above said layers on light-incident side of the device, as well as a protective laminating layer disposed on the photovoltaic conversion device on the side opposite to the substrate.
  • the deposition of films forming a first doped layer, a graded band gap layer and a second doped layer is performed by one of the methods of reactive chemical deposition from a gas phase selected from a group including CVD - Chemical Vapor Deposition, LPCVD - Low Pressure Chemical Vapor Deposition, PECVD - Plasma Enhanced Chemical Vapor Deposition, HF PECVD - High Frequency Plasma Enhanced Chemical Vapor Deposition, VHF PECVD - Very High Frequency Plasma Enhanced Chemical Vapor Deposition, HWCVD - Hot Wire Chemical Vapor Deposition. The latter is used in the proposed method most frequently.
  • a graded band gap layer hydrogen-, chlorine- and fluorine-containing gases are used, and change in composition of a graded band gap layer being achieved by smoothly changing the composition of gases and their volume consumption.
  • silicon carbide Si x Cy methane CH 4 or another carbon-containing gas is additionally introduced.
  • nitride Si x Ny nitrogen N 2 or ammonia NH3 are added.
  • Si x OyNz nitrogen and oxygen - N 2 and O2 are added.
  • graded band gap layer and second doped layer hydrogen is used, which allows to reduce the number of split atomic bonds in the films of layers of the photovoltaic conversion device to a level characterized by density of the defect states within the range of 10 16 - 10 17 cm ⁇ 3 and remove the defects of split bonds.
  • first conductive layer In sequentially forming on the substrate a first conductive layer, a first doped layer as a n-type layer, the graded band gap layer, a second doped layer as a p-type layer, and a second conductive layer, these layers are formed by one of the methods of physical or chemical deposition from gas phase, as PVD - Physical vapor Deposition, including Magnetron Sputtering, or CVD - Chemical Vapor Deposition, substantially HWCVD - Hot Wire Chemical Vapor Deposition.
  • PVD - Physical vapor Deposition including Magnetron Sputtering, or CVD - Chemical Vapor Deposition, substantially HWCVD - Hot Wire Chemical Vapor Deposition.
  • the n-type layer is formed on the substrate substantially by HWCVD via attacking by gas mixture comprising SiH 4 fed at flow rate of 20 - 150 seem, as well as additional gas mixture - 5% PH 3 and 95% H 2 , fed at a flow rate of 1 - 5 seem.
  • gas mixture comprising SiH 4 fed at flow rate of 20 - 150 seem, as well as additional gas mixture - 5% PH 3 and 95% H 2 , fed at a flow rate of 1 - 5 seem.
  • the substrate is heated to a temperature T SU b of 150 - 300 C 0 , and the forming process is performed at a pressure of 30 - 600 mT (milliTorr), filament current of 30 - 100 A during the deposition time - 300 - 600 sec.
  • the substrate is heated to a temperature T sub of 150 - 300 C 0 , and the forming process is performed at a pressure of 30 - 600 inT, filament current of 30 - 100 A during the deposition time - 600 - 1200 sec.
  • a gas mixture comprising silane - SiH 4 fed at a flow rate of 5 - 40 seem, as well as a mixture of gases 1,5% diborane - B 2 H 6 and 98,5% hydrogen - H2 fed at a flow rate of 1 - 5 seem.
  • the substrate is heated to a temperature T sub of 150 - 300 C 0 , and the forming process is performed at a pressure of 30 - 600 mT, filament current of 30 - 100 A during the deposition time - 300 - 600 sec.
  • the proposed thin-film photovoltaic conversion device is manufactured on the basis of at least one vacuum chamber wherein hydrogen-, chlorine- and fluorine-containing gases and when necessary, methane or another carbon- containing gas, nitrogen or ammonia and oxygen are fed, and smooth changing of composition of these gases and their volume consumption causes smooth composition changing of the graded band gap layer.
  • the proposed thin-film photovoltaic conversion device may also be manufactured on the basis of several vacuum chambers.
  • the n-type layer is formed in one of the vacuum chambers wherein the substrate is placed
  • the graded band gap layer is formed in the second of vacuum chambers wherein the substrate with the n-type layer already formed thereon is inserted, and then over this n-type layer a graded band gap layer is formed
  • the p-type layer is formed in the third of aforesaid vacuum chambers, wherein the substrate is inserted with n-type layer and graded band gap layer already deposited thereon, and then the p-type layer is deposited on this substrate over the graded band gap layer.
  • first conductive layer, reflective layer, second conductive layer, anti-reflective layer, as well as protective laminating layer, disposed on the photovoltaic conversion device on the side opposite to the substrate, are formed by the method of physical deposition PVD - Physical Vapor Deposition, including Magnetron Sputtering, in a fourth, additional vacuum chamber.
  • FIG. 1 is a cross section of a thin-film photovoltaic conversion device according to one embodiment of the present invention
  • FIG. 2 is a diagram of the inner part of a thin-film photovoltaic conversion device and its energetic (zone) diagram;
  • FIG. 3 is a diagram of the relationship between gases consumption
  • FIG. 4 is the diagram of a vacuum chamber for manufacturing a thin-film photovoltaic conversion device
  • FIG. 5 is the diagram of a four-chamber basic plant for manufacturing the thin-film photovoltaic conversion device
  • FIG. 6 is a cross section of a thin-film photovoltaic conversion device according to a second embodiment of the present invention.
  • a thin-film photovoltaic conversion device 1 having a substrate 2, a first conductive layer 3 together with a reflective layer 4 deposited on the surface of the latter, a first doped n-layer 5, a graded band gap layer 6, a second doped p-layer 7 and a second conductive transparent layer 8.
  • Substrate 2 of this conversion device 1 may be made of metal, glass or plastic.
  • substrate 2 is made from a flexible plastic, substantially polyimide.
  • First conductive layer 3 may have a reflective layer 4, made substantially from aluminium or silver and deposited on the surface of this layer near substrate 2, on the side opposite to light incidence direction.
  • First conductive layer 3 and first reflective layer 4 may be also formed as a single, substantially aluminium layer.
  • First conductive layer and second conductive layer, 3 and 8 respectively, of thin-film photovoltaic conversion device 1 are electrodes. One of these electrodes - second conductive layer 8 disposed relative to the layer 2 on the light incident side, as shown in FIG.l, is transparent.
  • thin-film photovoltaic conversion device 1 additionally comprises an anti-reflective layer 9 disposed relative to substrate 2 on the light incident side, a laminating protective layer 10, disposed on photovoltaic conversion device 1 on the side opposite to substrate 2, as well as a current pick-off grid 11 for tapping electric current from proposed device 1.
  • the first n- doped layer 5 and second doped p-layer 7 are disposed on both sides of side surfaces 12, 13 of graded band gap layer 6, one of them, the first n-doped layer 5, being disposed near side face 12 of graded band gap layer 6 on the side of substrate 2, and the second, p-type layer 7 - near side face 13, on the light incident side of device 1.
  • the most important member of proposed thin-film photovoltaic conversion device 1 is the graded band gap layer 6 having two side faces, 12, 13 respectively, and including pure silicon and silicon in chemical compositions with germanium, carbon, nitrogen, or nitrogen and oxygen, of the formula selected from the group consisting of: Si x Ge 1-X , Si x C y , Si x Ny, and Si x OyN 2 , wherein all these chemical compositions are simultaneously comprised in graded band gap layer 6, being disposed in layers and smoothly changing from one to the other.
  • graded band gap layer 6 is smoothly changing in light direction in aforesaid succession from side face 13 of a corresponding Si x Ge 1-X -layer to side face 12 of a corresponding Si x O y N z -layer.
  • Energy limits (Eg) of chemical composition layers, comprised in graded band gap layer 6 are changing, as shown in the diagram of FIG. 2, from 0,9 eV, which corresponds to the infrared region of the spectrum, to 3,5 eV, which corresponds to the ultraviolet region of solar spectrum.
  • Abbreviations in FIG.2 signify: Eg - energetic limit, Ec- conductivity zones, Ef - Fermi zone, Ev - valency zone.
  • Vacuum chamber 101 comprises a body 103, nozzle 105 with a gas inlet 107 for gas feeding and channel 109 connected with a pump 111.
  • the upper part of the chamber encloses a heater 113, whereon substrate 115 is secured, and over this substrate are successively deposited thin films 117.
  • FIG. 1 In the embodiment of vacuum chamber 101 shown in FIG.
  • HWCVD Hot Wire Chemical Vapor Deposition
  • PVD Physical vapor Deposition, including Magnetron Sputtering.
  • substrate 115 is secured on heater 113, and then thin films 117 are successively deposited thereover, which form a first conductive layer 3 with a reflective layer 4, first doped n-layer 5, graded band gap layer 6, second doped p-layer 7, a second conductive transparent layer 8, anti-reflective layer 9, protective layer 10 with a current collector grid 11.
  • the deposition of thin films 117 is performed by feeding into vacuum chamber 101 (FIG. 4) a mixture of silane SiH 4 with hydrogen H 2 and other gases.
  • Graded band gap layer 6, containing pure silicon and silicon in chemical compositions with germanium, carbon, nitrogen, or nitrogen and oxygen, of the formula selected from the group consisting of: Si x Ge 1- X , Si x Cy, Si x N y , and Si x OyN 2 is formed by feeding into vacuum chamber 101 hydrogen-, chlorine- and fluorine-containing gases, and, whenever necessary, methane or another carbon-containing gas, nitrogen or ammonia and oxygen, and smooth changing of composition and volume consumption of these gases provide smooth composition change of this graded band gap layer 6.
  • Si x Cy methane CH4 or other carbon-containing gases are added to aforesaid gases; to produce nitride Si x N y nitrogen N 2 or ammonia NH 3 are added; and to produce Si x O 7 N 2 nitrogen and oxygen - N 2 and O 2 are added.
  • a graded band gap layer 6 and a second doped p- layer 7 hydrogen is used, which allows to reduce the number of split atomic bonds in layer films of photovoltaic conversion device 1 being formed, to a level defined by density of the defect states within the range of 10 16 - 10 17 cm " and remove the defects of split bonds.
  • FIG. 3 presents a diagram of the relationship between consumption of gases being fed (cm 3 /win) and composition of graded band gap layer 6. The diagram symbolizes by lines:
  • n-type layer 5 is formed in vacuum chamber 101 (FIG. .4) on substrate 115 by a HWCVD method - Hot Wire Chemical Vapor Deposition, by attacking a gas mixture including silane - SiH 4 fed at a flow rate of 20 - 150 seem, and a mixture of gases - 5% phosphine - PH 3 and 95% hydrogen - H 2 fed at a flow rate of 1 - 5 seem.
  • substrate 115 is heated to a temperature T SU b of 150 - 300 C 0 and the forming process is going on at a pressure of 30 - 600 mT, filament current of 30 - 100 A during deposition time - 300 - 600 sec.
  • Graded band gap layer 6 is formed over n-type layer 5 in the same vacuum chamber 101 (FIG. 4) on substrate 115 by HWCVD method, via attacking a gas mixture including silane - SiH 4 fed at a flow rate of 0 - 150 seem, as well as a mixture of gases - germane - GeH 4 , methane - CH 4 or another carbon-containing gas, nitrogen N 2 or ammonia - NH 3 and oxygen - O 2 fed at a flow rate of 0 - 100 seem.
  • the ⁇ -type layer 7 is formed over graded band gap layer 6 in the same vacuum chamber 101 (FIG. 4) on substrate 115 by HWCVD method by attacking a gas mixture including silane - SiH 4 fed at a flow rate of 5 - 40 seem, as well as a mixture of gases - 1,5% diborane - B 2 H 6 and 98,5% hydrogen - H 2 fed at a flow rate of 1 - 5 seem.
  • the described method of manufacturing a thin-film photovoltaic conversion device 1 may be realized on the basis of several vacuum chambers 201, 203, 205, 207 (FIG. 5), which are designed like aforesaid vacuum chamber 101.
  • Vacuum chambers 201, 203, 205, 207 further comprise nozzles 213, 215, 217, 219 with gas inlets for gas feeding and channels 221, 223, 225, 227 connected with pumps.
  • the upper parts of vacuum chambers 201, 203, 205, 207 enclose heaters 231, 233, 235, 237 whereon substrates are secured, and over these substrates thin films are deposited.
  • FIG. 5 several vacuum chambers 201, 203, 205, 207
  • films forming the proposed p-type layer 7, graded band gap layer 6 and n-type layer 5 are deposited in vacuum chambers 201, 203, 205, by one of the methods of reactive chemical deposition from gas stage, selected from a group including CVD - Chemical Vapor Deposition, LPCVD - Low Pressure Chemical Vapor Deposition, PECVD - Plasma Enhanced Chemical Vapor Deposition, HF PECVD - High Frequency Plasma Enhanced Chemical Vapor Deposition, VHF PECVD - Very High Frequency Plasma Enhanced Chemical Vapor Deposition (30 - 300 MHz), HWCVD - Hot Wire Chemical Vapor Deposition.
  • the methods of reactive chemical deposition from gas stage selected from a group including CVD - Chemical Vapor Deposition, LPCVD - Low Pressure Chemical Vapor Deposition, PECVD - Plasma Enhanced Chemical Vapor Deposition, HF PECVD - High Frequency Plasma Enhanced Chemical Vapor Deposition, VHF PECVD - Very
  • n-type layer 5 in proposed thin-film photovoltaic conversion device 1 is formed in the first of vacuum chambers - chamber 201.
  • the substrate is inserted therein, and then, by the HWCVD method, n-type layer 5 is deposited to attack the gas mixture, including silane - SiH 4 fed at a flow rate of 20 - 150 seem, and a mixture of gases - 5% phosphine - PH 3 and 95% hydrogen - H 2 fed at a flow rate of 1 - 5 seem.
  • Graded band gap layer 6 in proposed thin-film photovoltaic conversion device 1 is formed in second vacuum chamber 203, wherein the substrate is inserted, and then, by HWCVD method, there is deposited thereon, over n-type layer 5, a graded band gap layer 6, attacking the gas mixture, including silane - SiH 4 fed at a flow rate of 0 - 150 seem, as well as the mixture of gases - germane - GeH 4 , methane - CH 4 or another carbon-containing gas, nitrogen N 2 or ammonia - NH3 and oxygen - O 2 fed at a flow rate of 0 - 100 seem.
  • the substrate is heated to a temperature T sub - 150 - 300 C 0 , and the forming process is going on in chamber 203 at a pressure of 30 - 600 mT, filament current 30 - 100 A during deposition time - 600 - 1200 sec.
  • the p-type layer 7 in proposed thin-film photovoltaic conversion device 1 is formed in the third of vacuum chambers 205 (FIG. 5), wherein the substrate is inserted, and then, by HWCVD method, there is deposited thereon, over graded band gap layer 6, the next p-type layer 7, attacking the gas mixture, including silane - SiH 4 fed at a flow rate of 5 - 40 seem, as well as a mixture of gases - 1,5% diborane - B 2 H 6 and 98,5% hydrogen - H 2 fed at a flow rate of 1 - 5 seem.
  • the substrate is heated to a temperature T SU b - 150 - 300 C 0 , and the forming process is going on in chamber 205 at a pressure of 30 - 600 mT, filament current 30 - 100 A during deposition time- 300 - 600 sec.
  • first conductive layer 3, reflective layer 4, second conductive layer 8, anti-reflective layer 9, as well as protective laminating layer 10, and collector grid 11 disposed on photovoltaic conversion device 1 on the side opposite to substrate 2 may be formed by a method of physical deposition from gas stage, and in particular, PVD - Physical Vapor Deposition, including Magnetron Sputtering, in the fourth vacuum chamber 207 (FIG. 5), having nozzle 219, gas inlet 227 for feeding gas, heater 237 and target 247.
  • the target 247 consists of material for layers 3, 4, 8,9,10, 11 depositions, for example, aluminium, silver, etc.
  • This example demonstrates the fabrication of photovoltaic conversion devices 1 as solar cells, including a substrate 115, first conductive layer 3 together with reflective layer 4 applied on its surface, first doped n-layer 5, graded band gap layer 6, second doped p-layer 7 and second conductive transparent layer 8.
  • Substrate 115 of this conversion device 1 is made of plastic polyimide.
  • the solar cell is fabricated in the following manner. In the described example substrate 115 of polyimide is secured on heater 113 (FIG.
  • first conductive layer 3 with reflective layer 4 first doped n-layer 5, graded band gap layer 6, second doped p- layer 7, second conductive transparent layer 8, anti-reflective layer 9 and, at last, protective layer 10 with collector grid 11.
  • High light absorption factor ( ⁇ >10 5 CM "1 ) of graded band gap layer 6 is achieved by smooth change of its composition on the light incident side: Si x Ge y - Si - Si x C y - Si x Ny - Si x OyN 2 .
  • first conductive layer 3 from aluminium or silver in the described example is performed by the well known magnetron sputtering method under following conditions: argon pressure 5 - 10 mT, cathode voltage 3 kV, cathode current 500 niA.
  • First doped n-layer 5 has been grown by the HW CVD method under the following conditions: T sub - 250° C; flow rate (5% SiH 4 , 95% H 2 ) - 100 seem; (5%
  • Second doped p-layer 7 has been grown by the HW CVD method under the following conditions: T SU b - 250° C; flow rate (5% SiH 4 , 95% H 2 ) - 100 scmm; (1,5 B 2 H 6 , 98,5% H 2 ) - 5 seem; pressure -
  • Si x Ge y - mixtures (5% SiH 4 + 95% H 2 ) and (5% GeH 4 + 95% H 2 ); for Si x C y - mixtures (5% SiH 4 + 95%H 2 ), (100% CH 4 or 100 % CO 2 ); for Si x Ny - mixture (5% SiH 4 + 95% H 2 ), (100% N 2 ); for Si x NyO 2 - mixture (5 % Si H 4 + 95% H 2 ), N 2 , O 2 .
  • This example demonstrates fabrication of photovoltaic conversion device 1 as solar cell, including a substrate 2 made of glass, first conductive layer 3 together with reflective layer 4 applied on its surface, first doped n-layer 5, graded band gap layer 6, second doped p-layer 7 and second conductive transparent layer 8.
  • the solar cell is fabricated in the following manner. Glass substrate 115 is secured on heater 113 (FIG. 4), and then thin films 117 are successively deposited thereover to form first conductive layer 3 with reflective layer 4, first doped n- layer 5, graded band gap layer 6, second doped p-layer 7, second conductive transparent layer 8, anti-reflective layer 9 and, at last, protective layer 10 with collector grid 11.
  • High light absorption factor ( ⁇ >10 5 CM "1 ) of the graded (varizone) semiconductor layer is achieved by smooth change of its composition on the light incident side: Si x Ge y _ Si - Si x Cy - Si x Ny - Si x O y N z .
  • the deposition of first conductive and reflective layer 3, 4 from aluminium or silver, as well as layers 8, 9, 10, 11 was performed by the well known magnetron sputtering method under following conditions: argon pressure 5 - 10 mT, cathode voltage 3 kV, cathode current 500 mA.
  • First doped n-layer 5 is grown by the HW CVD method under the following conditions: T sub - 250° C; flow rate (5% SiH 4 , 95% H 2 ) - 100 seem; (5% PH 3 , 95% H 2 ) - 3 seem; pressure - 250 mT.
  • Second p-type doped layer is grown by the HW CVD method under following conditions: T sub - 250 0 C; flow rate (5% SiH 4 , 95% H 2 ) - 100 seem; (1.5% B 2 H 6 , 98.5% H 2 ) -5 seem; pressure - 250 mT.
  • the growth is performed in the medium of silane (SiH 4 ) diluted with hydrogen (H 2 ).
  • a gas from three- valent chemical elements of the periodic system such as diborane (B 2 H 6 ) is added to the gas mixture.
  • a gas on the basis of five-valent elements of the periodic system is added to the gas mixture, such as phoshorus, arsenic, antimony, in particular, phosphine (PH 3 ).
  • This example demonstrates the fabrication of photocells with reverse disposition of layers.
  • photocell 1 When photocell 1 is exposed to daylight on the side of transparent substrate 2, the order of layers deposition is changed.
  • a metal grid (comb) 11 On glass substrate 2 there is applied a metal grid (comb) 11, then a transparent electroconductive and anti-reflective coating 9. Therewith protective layer 10 is excluded.
  • n-doped layer 5 is deposited.
  • Graded band gap 6 is also deposited in reverse order: Si x OyN 2 - Si x Ny - Si x C y - Si - Si x Ge y .
  • doped p-layer 7 On the surface of graded (varizone) semiconductor layer 6 there is deposited doped p-layer 7 and then a metal current collector and reflective layer 3, 4 (Back-Contact).
  • Substrate 2 is secured on heater 113, and then, thereover thin films 117 are successively deposited.
  • Anti-reflective coating 9, metal grid (comb) 11, current collector and reflective layers 3, 4 are deposited by the well known magnetron sputtering method under following conditions: argon pressure - 5 - 10 mT, cathode voltage - 3 kV, cathode current 500 niA.
  • First doped n-layer 5 is grown by the HW CVD method under the following conditions: T sub - 250° C; flow rate (5% SiH 4 , 95% H 2 ) - 100 seem; (5% PH 3 , 95%
  • Second doped ⁇ -layer 7 is grown by the HW
  • Si x Ge y - mixtures (5% SiH 4 + 95% H 2 ) and (5% GeH 4 + 95% H 2 ); for Si x Cy - mixtures (5% SiH 4 + 95% H 2 ), (100% CH 4 or 100 %CO 2 ); for Si x Ny - mixture (5% SiH 4 + 95% H 2 ), (100% N 2 ); for Si x NyO 2 - mixture (5 % SiH 4 + 95% H 2 ), N 2 , 0 2 .
  • Conductive layer 3 and reflective layer 4 are fabricated from metals with high factor light reflection and high electroconductivity - aluminium or silver. They serve as upper collector electrodes.
  • Layer 11 - the grid or comb is a lower collector electrode and is also fabricated from metals with high electroconductivity. The total surface of this layer should not exceed 5 - 10% of the cell total surface, and the distance between grid 11 lines is 5 - 50 mm.
  • These layers are deposited by the PVD method - Physical Vapor Deposition.
  • Conductive transparent layer 8 is transparent to light and has a low electric resistance. The layer is produced from a mixture of indium tin oxide (ITO) or zinc oxide alloyed by aluminium - ZnO/ Al. This layer is also deposited by the PVD method.
  • This example demonstrates the fabrication of p-type layer 7, graded band gap layer 6 and n-type layer 5 in the first three chambers 201, 203, 205 (FIG.5).
  • the layers in these three chambers are deposited by the HVCVD method.
  • heater 231 is turned on to heat the substrate to a temperature of 250° C.
  • Filament heater 241 is turned on to heat this filament to a temperature of 1600 - 2000° C.
  • the substrate with deposited films is displaced to chamber 203 for deposition graded band gap layer 6 and submitted to aforesaid operations.
  • the gas composition fed into the chamber 203 is as follows: 5% SiH 4 + 95% H 2 ; 5% GeH 4 + 5% H 2 ; 100% N 2 ; 100% CH 4 ; 100% O 2 .
  • Gas consumption is changing according to the diagram shown in FIG. 3.
  • the substrate with films is displaced to chamber 205 (FIG. 5).
  • heater 235 is turned on to heat the substrate to a temperature of 250 0 C.
  • the substrate with deposited films is displaced to chamber 207 wherein these layers are deposited by the method of physical deposition from gas phase - PVD - Physical Vapor Deposition, including magnetron sputtering.
  • Chamber 207 has a nozzle 219, channel 227 for gas feeding, heater 237 and target 247.
  • Target 247 consists of a material that must be deposited as layers 3, 4, 8, 9, 10, 11, such as aluminium, silver etc.
  • the advantages of proposed photovoltaic conversion device 1 and method of its fabrication are as follows. In most known photovoltaic conversion devices there is used a homogeneous i-layer or a cascade of these layers with a definite band gap layer and limited possibilities of light conversion.
  • the proposed photovoltaic conversion device and method of its fabrication allow to set up the production of semi-conductors wherein, instead of one or several i-layers, there is formed one layer of a complex smoothly changeable structure Si x Ge 1-x - Si - Si x C y - Si x Ny - Si x OyN z .

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  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Photovoltaic Devices (AREA)

Abstract

La présente invention concerne un dispositif de conversion photovoltaïque à couche mince, formé sur un substrat, de préférence composé d'un plastique flexible, comportant des première et seconde couches conductrices servant d'électrodes, des couches de type n et de type p, une couche de bande interdite à gradient (varizone) comprenant du silicium pur et du silicium en compositions chimiques sélectionnées parmi le groupe constitué de SixGe1-x, SixCy, SixNy et SixOyNz, toutes ces compositions chimiques étant comprises simultanément dans une couche à bande interdite à gradient et variant légèrement de l'une à l'autre. Le dispositif photovoltaïque comprend en outre une couche réfléchissante, une couche antireflet et une couche de stratification protectrice. Le dispositif est fabriqué sur la base d'au moins une chambre à vide selon deux modes de réalisation du procédé selon l'invention.
PCT/IL2007/000847 2006-07-16 2007-07-08 Dispositif de conversion photovoltaïque à couche mince et son procédé de fabrication WO2008010205A2 (fr)

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IL176885 2006-07-16
IL176885A IL176885A0 (en) 2006-07-16 2006-07-16 A thin-film photovoltaic conversion device and method of manufacturing the same

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2161758A1 (fr) 2008-09-05 2010-03-10 Flexucell ApS Cellule solaire et son procédé de fabrication
CN102593253A (zh) * 2012-02-23 2012-07-18 上海中智光纤通讯有限公司 一种异质结晶硅太阳电池钝化层的制备方法
WO2014023560A1 (fr) * 2012-08-10 2014-02-13 Commissariat A L'energie Atomique Et Aux Energies Alternatives Materiau absorbeur a base de cu2znsn(s,se)4 a gradient de separation de bandes pour des applications photovoltaïques en couches minces

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Publication number Priority date Publication date Assignee Title
US4816082A (en) * 1987-08-19 1989-03-28 Energy Conversion Devices, Inc. Thin film solar cell including a spatially modulated intrinsic layer
US5114498A (en) * 1989-03-31 1992-05-19 Sanyo Electric Co., Ltd. Photovoltaic device
US5759291A (en) * 1995-06-28 1998-06-02 Canon Kabushiki Kaisha Photovoltaic cell and method of making the same

Patent Citations (3)

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Publication number Priority date Publication date Assignee Title
US4816082A (en) * 1987-08-19 1989-03-28 Energy Conversion Devices, Inc. Thin film solar cell including a spatially modulated intrinsic layer
US5114498A (en) * 1989-03-31 1992-05-19 Sanyo Electric Co., Ltd. Photovoltaic device
US5759291A (en) * 1995-06-28 1998-06-02 Canon Kabushiki Kaisha Photovoltaic cell and method of making the same

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2161758A1 (fr) 2008-09-05 2010-03-10 Flexucell ApS Cellule solaire et son procédé de fabrication
WO2010025734A1 (fr) 2008-09-05 2010-03-11 Flexucell Aps Cellule solaire comprenant un substrat ondulé flexible et son procédé de production
CN102593253A (zh) * 2012-02-23 2012-07-18 上海中智光纤通讯有限公司 一种异质结晶硅太阳电池钝化层的制备方法
WO2014023560A1 (fr) * 2012-08-10 2014-02-13 Commissariat A L'energie Atomique Et Aux Energies Alternatives Materiau absorbeur a base de cu2znsn(s,se)4 a gradient de separation de bandes pour des applications photovoltaïques en couches minces
FR2994507A1 (fr) * 2012-08-10 2014-02-14 Commissariat Energie Atomique Materiau absorbeur a base de cu2znsn(s,se)4 a gradient de separation de bandes pour des applications photovoltaiques en couches minces

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WO2008010205A3 (fr) 2009-05-07

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