Method of forming single-crystal semiconductor layers and photovaltaic cell thereon

Patent metadata

Field	Value
Publication number	US-9356171-B2
Application number	US-201213401206-A
Country	US
Kind code	B2
Filing date	Feb 21, 2012
Priority date	Jan 25, 2012
Publication date	May 31, 2016
Grant date	May 31, 2016

Abstract

A method for forming single crystal or large-crystal-grain thin-film layers deposits a thin-film amorphous, nanocrystalline, microcrystalline, or polycrystalline layer, and laser-heats a seed spot having size on the order of a critical nucleation size of the thin-film layer. The single-crystal seed spot is extended into a single-crystal seed line by laser-heating one or more crystallization zones adjacent to the seed spot and drawing the zone across the thin-film layer. The single-crystal seed line is extended across the thin-film material layer into a single-crystal layer by laser-heating an adjacent linear crystallization zone and drawing the crystallization zone across the thin-film layer. Photovoltaic cells may be formed in or on the single-crystal layer. Tandem photovoltaic devices may be formed using one or several iterations of the method. The method may also be used to form single-crystal semiconductor thin-film transistors, such as for display devices, or to form single-crystal superconductor layers.

First claim

What is claimed is:

1. A method for forming a single-crystal thin-film material layer of a first material comprising:
depositing a thin-film material layer on a surface selected from a substrate and a template layer on a substrate, the thin-film semiconductor layer having an initial microstructure selected from the group consisting of amorphous, nanocrystalline, microcrystalline, and polycrystalline;
laser-heating to a crystallization temperature a seed spot in the thin-film material layer between one and one thousand nanometers in diameter of the thin-film material layer, using a laser focal spot size on the order of a critical size of nucleation of the thin-film material layer, the seed spot having size on the order of the critical size of nucleation of the thin-film material layer, and thereby crystalizing the seed spot; the crystallized seed spot consisting of a single crystal seed in the thin-film material layer;
extending the seed spot into a single-crystal seed line by laser-heating at least one crystallization zone adjacent to the seed spot and drawing the crystallization zone across the thin-film material layer; and
extending the single crystal seed line across the thin-film material layer by laser-heating a crystallization zone adjacent to the seed line and drawing the crystallization zone across the thin-film semiconductor layer.

2. The method of claim 1 wherein the thin-film material layer comprises a material selected from the group consisting of Silicon, Germanium, Gallium Arsenide, Gallium Phosphide, Indium Gallium Phosphide, Cadmium Telluride, Copper Indium Gallium diSelenide, Cupric or Cuprous Oxide, Zinc Oxide, Zinc Phosphide, and Indium Gallium Nitride.

3. The method of claim 2 wherein the thin-film material has amorphous initial microstructure.

4. The method of claim 2 wherein the thin-film material comprises primarily silicon.

5. The method of claim 4 wherein the thin-film semiconductor material has amorphous initial microstructure.

6. The method of claim 1 , wherein said surface is a substrate comprising a non-single-crystal material selected from the group consisting of glass, plastics, metal, or ceramics.

7. The method of claim 1 , wherein said surface comprises a template layer comprising a non-single-crystal material from the group consisting of a silicon oxide, silicon nitride, silicon oxynitride, or amorphous silicon.

8. The method of claim 1 wherein the seed spot has size not greater than twice the critical size of nucleation.

9. The method of claim 1 further comprising depositing a second thin-film layer comprising a semiconductor second material chemically different from the first material.

10. The method of claim 9 wherein the step of laser heating is performed after the step of depositing the second semiconductor material, and both the first and second thin-film layers are crystallized during the step of laser heating.

11. The method of claim 9 wherein the step of laser heating is performed prior to depositing the second thin-film layer.

12. The method of claim 11 further comprising:
a second laser heating to form a second seed spot, the second laser heating performed with a laser spot size on the order of a critical size of nucleation of the second thin-film layer;
extending the second seed spot into a second single-crystal seed line in the second thin-film semiconductor layer by laser-heating at least one crystallization zone adjacent to the seed spot and drawing the crystallization zone across the second thin-film layer; and
extending the single crystal seed line across the second thin-film layer by laser-heating a crystallization zone adjacent to the seed line and drawing the crystallization zone across the second thin-film layer.

13. The method of claim 9 further comprising depositing a third thin-film layer of a semiconductor third material chemically different from the first and second materials.

14. The method of claim 13 further comprising:
a third laser heating to form a third seed spot;
extending the third seed spot into a third single-crystal seed line in the third thin-film layer by laser-heating at least one crystallization zone adjacent to the seed spot and drawing the crystallization zone across the third thin-film layer; and
extending the single crystal seed line across the third thin-film semiconductor layer by laser-heating a crystallization zone adjacent to the seed line and drawing the crystallization zone across the third thin-film layer.

15. The method of claim 1 wherein the thin-film semiconductor layer comprises at least a first and a second sublayer, and wherein the step of extending the seed line crystallizes at least the first, but not the second, sublayer.

16. A method of fabricating a photovoltaic device comprising:
depositing an electrical contact layer on a surface;
depositing a first thin-film semiconductor layer, the first thin-film semiconductor layer having an initial microstructure selected from the group consisting of amorphous, nanocrystalline, and microcrystalline;
laser-heating to a crystallization temperature a seed spot of the first thin-film semiconductor layer, the seed spot having size between one and one thousand nanometers diameter and on the order of a critical size of nucleation of the first thin-film semiconductor layer, and thereby crystalizing the first seed spot into a seed consisting of a single crystal, wherein the laser heating of the seed spot is performed with a laser focal spot size on the order of the critical size of nucleation;
extending the seed spot into a first single-crystal seed line by laser-heating at least one crystallization zone adjacent to the seed spot and drawing the crystallization zone across the first thin-film semiconductor layer;
extending the first single crystal seed line across the thin-film semiconductor layer by laser-heating a crystallization zone adjacent to the first seed line and drawing the crystallization zone across the first thin-film semiconductor layer;
constructing a first junction using the first thin-film semiconductor layer; and
applying contact metallization.

17. The method of claim 16 further comprising:
depositing a second thin-film semiconductor layer, the second thin-film semiconductor layer having an initial microstructure selected from the group consisting of amorphous, nanocrystalline, and microcrystalline;
laser-heating to a crystallization temperature a second seed spot of the second thin-film semiconductor layer, the seed spot having size on the order of a critical size of nucleation of the second thin-film semiconductor layer, and thereby crystalizing the second seed spot into a single-crystal seed;
extending the second seed spot into a second single-crystal seed line by laser-heating at least one crystallization zone adjacent to the seed spot and drawing the crystallization zone across the second thin-film semiconductor layer;
extending the second single crystal seed line across the thin-film semiconductor layer by laser-heating a crystallization zone adjacent to the second seed line and drawing the crystallization zone across the second thin-film semiconductor layer;
constructing a second junction using the second thin-film semiconductor layer.

18. A method of fabricating a tandem photovoltaic device comprising:
depositing an electrical contact layer on a transparent substrate;
depositing a thin-film semiconductor layer, the thin-film semiconductor layer having an initial microstructure selected from the group consisting of amorphous, nanocrystalline, and microcrystalline, the t

Assignees

• Liu Jifeng
• Wang Xiaoxin
• Dartmouth College

Inventors

• Liu Jifeng
• Wang Xiaoxin

Classifications

• H10F77/1642

  including only Group IV materials · CPC title

• H10F71/131

  Recrystallisation; Crystallization of amorphous or microcrystalline semiconductors · CPC title

• H10F10/172

  comprising multiple PIN junctions, e.g. tandem cells · CPC title

• H10F77/164 Primary

  Polycrystalline semiconductors · CPC title

• H01L31/0368 Primary

  Electricity · mapped topic