Thin films of mixed metal compounds
First Claim
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1. A method for forming a uniform composition thin film of a polycrystalline mixed metal compound on a substrate, said method consisting essentially of the steps of:
- (a) introducing a vapor of a first metal compound to a vessel containing said substrate from a first vapor source while simultaneously introducing a vapor of a second metal compound from a second vapor source to said vessel to form a vapor mixture comprised of metal compounds, said first and second metals comprising the metal components of said mixed metal compound;
(b) independently controlling the vaporization rate of said first and second vapor sources;
(c) reducing the mean free path between vapor particles of said mixture in said vessel by including a gas within said vessel, said gas being present in an amount sufficient to induce homogeneity of said vapor mixture; and
(d) depositing said homogeneous vapor mixture on said substrate to form a uniform composition polycrystalline film of said first and second metal compounds thereon.
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Abstract
A compositionally uniform thin film of a mixed metal compound is formed by simultaneously evaporating a first metal compound and a second metal compound from independent sources. The mean free path between the vapor particles is reduced by a gas and the mixed vapors are deposited uniformly. The invention finds particular utility in forming thin film heterojunction solar cells.
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Citations
18 Claims
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1. A method for forming a uniform composition thin film of a polycrystalline mixed metal compound on a substrate, said method consisting essentially of the steps of:
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(a) introducing a vapor of a first metal compound to a vessel containing said substrate from a first vapor source while simultaneously introducing a vapor of a second metal compound from a second vapor source to said vessel to form a vapor mixture comprised of metal compounds, said first and second metals comprising the metal components of said mixed metal compound; (b) independently controlling the vaporization rate of said first and second vapor sources; (c) reducing the mean free path between vapor particles of said mixture in said vessel by including a gas within said vessel, said gas being present in an amount sufficient to induce homogeneity of said vapor mixture; and (d) depositing said homogeneous vapor mixture on said substrate to form a uniform composition polycrystalline film of said first and second metal compounds thereon. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of making a thin film heterojunction solar cell comprised of a substrate of a I-III-VI2 chalcopyrite having a thin film of a uniform composition mixed metal compound deposited thereon, said method consisting essentially of the steps of:
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(a) introducing a vapor of a first metal compound to a vessel from a first vapor source while simultaneously introducing a vapor of a second metal compound from a second vapor source to said vessel thereby forming a vapor comprised of said first metal compound and said second metal compound, said first and second metals comprising the mixed metal compound;
having a common electronegative element;(b) independently controlling the vaporization rate of said first and second vapor sources; and (c) reducing the mean free path between vapor particle in said vessel by including a gas within said vessel, said gas being present in an amount sufficient to induce homogeneity of said vapor mixture and thereby produce a uniform composition thin film of a polycrystalline mixed metal compound comprised of said first and second metals and said common electronegative element on said substrate. - View Dependent Claims (11, 12, 13)
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14. A thin film heterojunction solar cell, said heterojunction comprising a p-type I-III-IV2 chalcopyrite substrate and an overlying layer of an n-type ternary mixed metal compound wherein said ternary mixed metal compound is applied to said substrate by introducing the vapor of a first metal compound to a vessel containing said substrate from a first vapor source while simultaneously introducing a vapor of a second metal compound from a second vapor source of said vessel, said first and second metals comprising the metal components of said mixed metal compound;
- independently controlling the vaporization rate of said first and second vapor sources;
reducing the mean free path between vapor particles in said vessel, said gas being present in an amount sufficient to induce homogeneity of said vapor mixture; and
depositing said mixed metal compound on said substrate in the form of a uniform composition polycrystalline mixed metal compound. - View Dependent Claims (15, 16, 17, 18)
- independently controlling the vaporization rate of said first and second vapor sources;
Specification