Patent US4781766A successfully refreshed from Google Patents.
US4781766A
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Fault tolerant thin-film photovoltaic cell and method
Assignee: Heritage Power LLC
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Filing: 1987-05-29
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Granted: 1988-11-01
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Expires: 2007-05-29
Abstract
Abstract A thin-film solar cell is made up of semiconductor layers formed on an aluminum silicon eutectic alloy substrate. The substrate includes an aluminum oxide insulator containing electrically conducting silicon nucleation sites which is interposed between the electrical contact of the substrate and the adjacent semiconductor. Grain boundaries and voids terminate on the insulator. The solar cell is fabricated by oxidizing the aluminum-silicon substrate to form a layer of aluminum oxide with unactivated silicon site material dispersed therein and activating the silicon nucleation sites during growth of the semiconductor layers.
Inventors
- 👤 Allen M. Barnett
- 👤 Robert B. Hall
- 👤 Jeff W. Edington
- 👤 Alexander P. Davidson
- 👤 William A. Tiller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 04:43
CPC Classifications
H; H10; H10F; H10F10/00; H10F10/10; H10F77/00; H10F77/10; H10F77/16; H10F77/169; H10F77/1692; H10F77/20; H10F77/206; H10F77/211; Y; Y02; Y02E; Y02E10/00; Y02E10/50; Y10; Y10S; Y10S257/00; Y10S257/928
Claims Analysis
Total Claims: 36
Claim 1
Independent Claim
89 words
A process for fabricating a thin-film photovoltaic solar cell comprising the steps of: a. forming a substrate from a selected metal with a selected nucleation site material dispersed therein; b. forming on at least one surface of the substrate a layer of an electrically insulative material comprising a compound of the selected metal; c. activating the site material to form electrically conductive nucleation sites; d. forming at least one semiconductor layer over the insulative material having activated nucleation sites; and e. applying electrical contact means to the solar cell.
Claim 2
Dependent Claim
89 words
A process for fabricating a thin-film photovoltaic solar cell comprising the steps of: a. forming a substrate from a selected metal with a selected nucleation site material dispersed therein; b. forming on at least one surface of the substrate a layer of an electrically insulative material comprising a compound of the selected metal; c. activating the site material to form electrically conductive nucleation sites; d. forming at least one semiconductor layer over the insulative material having activated nucleation sites; and e. applying electrical contact means to the solar cell.
Claim 3
Dependent Claim
21 words
The process of claim 1 wherein the insulative material is aluminum oxide and the electrically conductive nucleation site material is silicon.
Claim 4
Dependent Claim
61 words
The process of claim 1 wherein said step of forming the substrate is preparing an aluminum silicon eutectic mixture having a composition of 87.4% aluminum with 12.6% silicon, melting the mixture above the eutectie point of 577° C., rapidly cooling the molten mixture to form an ingot containing silicon crystallites dispersed therein and shaping the ingot to form a thin sheet.
Claim 5
Dependent Claim
23 words
The process of claim 1 wherein the step of forming the insulative material is selected from thermal oxidation, electrolytic anodization or plasma oxidation.
Claim 6
Dependent Claim
36 words
The process of claim 4 wherein the step of forming the insulative material is thermal oxidation by exposure to oxygen at a temperature of 200° to 400° C. for a period of 2 to 20 minutes.
Claim 7
Dependent Claim
24 words
The process of claim 5 wherein the step of forming the insulative material is exposure to dry oxygen for 10 minutes at 300° C.
Claim 8
Dependent Claim
20 words
The process of claim 1 wherein the step of forming at least one semiconductor layer is the solution growth process.
Claim 9
Dependent Claim
24 words
The process of claim 7 wherein the step of activating the site material occurs during the step of forming at least one semiconductor layer.
Claim 10
Dependent Claim
27 words
The process of claim 8 wherein the step of activating the site material is provided by adding a selected chemical reducing agent to the solution growth solvent.
Claim 11
Dependent Claim
31 words
The process of claim 9 wherein the at least one semiconductor layer is silicon, and the solution growth solvent is selected from tin, gallium, bismuth, indium, lead, germanium, and alloys thereof.
Claim 12
Dependent Claim
12 words
The process of claim 10 wherein the selected reducing agent is aluminum.
Claim 13
Dependent Claim
53 words
The process of claim 10 wherein the substrate is an aluminum sheet containing silicon, the electrically insulative material is aluminum oxide, the electrically conductive nucleation sites are silicon, and the at least one semiconductor layer is formed by solution growth from molten tin containing aluminum as a reducing agent for activating the sites.
Claim 14
Dependent Claim
25 words
The process of claim 1 wherein the at least one layer is a compound semiconductor selected from groups III and V of the Periodic Table.
Claim 15
Dependent Claim
19 words
The process of claim 13 wherein the at least one layer is two oppositely doped layers of gallium aresenide.
Claim 16
Dependent Claim
53 words
The process of claim 14 wherein the substrate is an aluminum sheet containing silicon, the electrically insulative material is aluminum oxide, the electrically conductive nucleation sites are silicon, and the at least one semiconductor layer is formed by solution growth from molten gallium containing aluminum as a reducing agent for activating the sites.
Claim 17
Dependent Claim
27 words
The process of claim 1 including the step of chemically etching the substrate prior to said step of forming the insulative material thereby exposing the site material.
Claim 18
Dependent Claim
26 words
The process of claim 1 wherein the step of forming the substrate includes texturing the surface of the substrate to provide for diffuse reflection of light.
Claim 19
Dependent Claim
29 words
The process of claim 1 wherein the step of forming the insulative compound includes forming the insulative compound to a preselected thickness which provides for enhanced reflection of light.
Claim 20
Dependent Claim
14 words
The process of claim 18 wherein the preselected thickness satisfies the quarter-wave reflector condition.
Claim 21
Dependent Claim
112 words
In a thin-film photovoltaic solar cell having as its components a substrate functioning as a first electrical contact, at least one semiconductor layer, including at least one photovoltaic junction, and a second electrical contact, the improvement being an aluminum substrate containing silicon in the amount of 5 to 25 weight percent, and an insulator interposed between the substrate and said at least one semiconductor layer, said insulator comprising a mixture of aluminum oxide and silicon oxide, and said insulator containing electrically conductive silicon nucleation sites dispersed therein, whereby microscopic and macroscopic defects terminate on the insulator and the sites provide for electrical communication between the first electrical contact and the semiconductor layer.
Claim 22
Dependent Claim
112 words
In a thin-film photovoltaic solar cell having as its components a substrate functioning as a first electrical contact, at least one semiconductor layer, including at least one photovoltaic junction, and a second electrical contact, the improvement being an aluminum substrate containing silicon in the amount of 5 to 25 weight percent, and an insulator interposed between the substrate and said at least one semiconductor layer, said insulator comprising a mixture of aluminum oxide and silicon oxide, and said insulator containing electrically conductive silicon nucleation sites dispersed therein, whereby microscopic and macroscopic defects terminate on the insulator and the sites provide for electrical communication between the first electrical contact and the semiconductor layer.
Claim 23
Dependent Claim
28 words
In the solar cell of claim 20 wherein the substrate is aluminum and silicon at the eutectic ratio of 87.4 weight percent aluminum and 12.6 weight percent silicon.
Claim 24
Dependent Claim
15 words
In the solar cell of claim 20 wherein the aluminum substrate is in sheet form.
Claim 25
Dependent Claim
16 words
In the solar cell of claim 20 wherein the insulator is 0.1 to 100 micrometers thick.
Claim 26
Dependent Claim
24 words
In the solar cell of claim 20 wherein the silicon nucleation sites are heavily doped silicon having a resistivity of less than 0.1 ohm-cm.
Claim 27
Dependent Claim
17 words
In the solar cell of claim 24 wherein the heavily doped silicon is silicon doped with aluminum.
Claim 28
Dependent Claim
44 words
In the solar cell of claim 20 wherein the at least one semiconductor layer is polycrystalline and the size and distribution of sites within the insulator are selected such that grain size in the semiconductor layer and electrical resistance within the cell are optimum.
Claim 29
Dependent Claim
13 words
In the solar cell of claim 20 wherein the insulator is optically transparent.
Claim 30
Dependent Claim
14 words
In the solar cell of claim 20 wherein the substrate is reflective to light.
Claim 31
Dependent Claim
23 words
In the solar cell of claim 20 wherein the thickness of the insulator is selected whereby the insulator serves as a quarter-wave reflector.
Claim 32
Dependent Claim
20 words
In the solar cell of claim 20 wherein the substrate surface is textured to provide for diffuse reflection of light.
Claim 33
Dependent Claim
27 words
In the solar cell of claim 20 wherein the solar cell is a silicon solar cell comprising oppositely doped regions of silicon semiconductor and a homojunction therebetween.
Claim 34
Dependent Claim
29 words
In the solar cell of claim 20 wherein the solar cell is a gallium arsenide solar cell comprising oppositely doped regions of gallium arsenide semiconductor and a homojunction therebetween.
Claim 35
Dependent Claim
25 words
In the solar cell of claim 20 wherein the semiconductor includes oppositely doped layers of gallium arsenide and gallium aluminum arsenide and a heterojunction therebetween.
Claim 36
Dependent Claim
24 words
In the solar cell of claim 20 wherein the semiconductor includes oppositely doped layers of gallium arsenide and gallium phosphide and a heterojunction therebetween.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-11-01 | 1992-05-02 | 1992-11-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-11-01 | 1996-05-02 | 1996-11-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-11-01 | 2000-05-02 | 2000-11-01 | $7700.00 | Window Closed / Lapsed |