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EP0045195A2
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Semiconductor device, a method of making a low-resistance contact between a metal and a layer of polycrystalline P-type CdTe in said semiconductor device and a cadmium-selective etchant which is useful for said method
Assignee: Eastman Kodak Co
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Filing: 1981-07-24
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Granted: —
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Expires: 2001-07-24
Abstract
Abstract A semiconductor device comprises a layer 12 of polycrystalline p-type cadmium telluride and a layer 16 of metal in low resistance contact with the cadmium telluride layer. A layer 14 of tellurium is disposed between the cadmium telluride layer 12 and the metal layer 16 which permits the use of non auric metals for the layer 16 provided that the surface portion 18 of the cadmium telluride layer is cadmium deficient and has intact grain boundaries. The tellurium layer 14 may be formed by selectively dissolving cadmium from the cadmium telluride layer 12. The cadmium may be dissolved by etching the layer 12 with a mixture of nitric acid and a leveling agent e.g. phosphoric acid.
Inventors
- 👤 Yuan-Sheng Tyan
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 17:42
CPC Classifications
H; H10; H10D; H10D62/00; H10D62/80; H10D62/86; H10D62/8603; H10D64/00; H10D64/01; H10D64/011; H10F; H10F77/00; H10F77/20; H10F77/206; H10F77/211; Y; Y02; Y02E; Y02E10/00; Y02E10/50; Y02E10/543
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
73 words
A semiconductor device, particularly a photovoltaic cell (12) of polycrystalline p-type cadmium telluride and a layer (16) of metal in low-resistance contact with said cadmium telluride, characterized in that an interlayer (14) comprising tellurium is disposed between and in contact with said cadmium telluride layer and said metal layer, and that the surface portion (18) of said cadmium telluride layer (12) in contact with said tellurium interlayer is cadmium-deficient, with intact grain bounderies.
Claim 2
Dependent Claim
73 words
A semiconductor device, particularly a photovoltaic cell (12) of polycrystalline p-type cadmium telluride and a layer (16) of metal in low-resistance contact with said cadmium telluride, characterized in that an interlayer (14) comprising tellurium is disposed between and in contact with said cadmium telluride layer and said metal layer, and that the surface portion (18) of said cadmium telluride layer (12) in contact with said tellurium interlayer is cadmium-deficient, with intact grain bounderies.
Claim 3
Dependent Claim
76 words
A semiconductor device comprising a layer (12) of polycrystalline p-type cadmium telluride and a layer (16) of metal in low-resistance contact with said cadmium telluride layer, characterized in that an interlayer comprising tellurium is disposed between and in contact with said cadmium telluride layer and said metal layer, said tellurium-comprising interlayer being formed by selectively dissolving cadmium from the exterior portion of an initial cadmium telluride layer, and said cadmium telluride layer having intact grain boundaries.
Claim 4
Dependent Claim
76 words
A semiconductor device comprising a layer (12) of polycrystalline p-type cadmium telluride and a layer (16) of metal in low-resistance contact with said cadmium telluride layer, characterized in that an interlayer comprising tellurium is disposed between and in contact with said cadmium telluride layer and said metal layer, said tellurium-comprising interlayer being formed by selectively dissolving cadmium from the exterior portion of an initial cadmium telluride layer, and said cadmium telluride layer having intact grain boundaries.
Claim 5
Dependent Claim
35 words
A device as defined in claim 1 or 2, characterized in that said metal is selected from the group consisting of silver, nickel, chromium, copper, tin, aluminium, gold, titanium, lead, stainless steel, and nuckel alloys.
Claim 6
Independent Claim
53 words
A method of forming a low resistance contact between a metal and a layer of polycrystalline p-type cadmium telluride characterized by forming a cadmium deficient tellurium surface region on the p-type cadmium telluride, while maintaining the grain boundaries of the cadmium telluride intact, and applying a layer of metal to the tellurium surface.
Claim 7
Independent Claim
53 words
A method of forming a low resistance contact between a metal and a layer of polycrystalline p-type cadmium telluride characterized by forming a cadmium deficient tellurium surface region on the p-type cadmium telluride, while maintaining the grain boundaries of the cadmium telluride intact, and applying a layer of metal to the tellurium surface.
Claim 8
Dependent Claim
27 words
A method as defined in claim 4 characterized in that the cadmium deficient tellurium surface region is formed by selectively dissolving cadmium from the p-type cadmium telluride.
Claim 9
Dependent Claim
33 words
A method as defined in claim 5 characterized in that said dissolving step comprises etching said initial cadmium telluride layer with a mixture of nitric acid or salts thereof and a leveling agent.
Claim 10
Dependent Claim
28 words
A method as defined in claim 5 or 6 characterized in that the cadmium is dissolved from the p-type cadmium telluride for between 5 seconds and 2 minutes.
Claim 11
Dependent Claim
62 words
A cadmium-selective etchant for a layer of p-type polycrystalline cadmium telluride, which can be used in the method of claims 4, 5 or 6, characterized in that it comprises a mixture of a leveling agent and an effective amount of nitric acid or salts thereof for selective removal of cadmium from said layer without degrading the grain boundaries of said polycrystalline layer.
Claim 12
Dependent Claim
17 words
An etchant as defined in claim 8, characterized in that said leveling agent is concentrated phosphoric acid.
Claim 13
Dependent Claim
29 words
An etchant as defined in claims 8 or 9, characterized in that said nitric acid or salts thereof is present in an amount of between 0.10 and 5.0 percent.
References Cited (Backward Citations)
No citation records indexed.
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