Technique for achieving large-grain Ag2ZnSn(S,Se)4thin films

Patent metadata

Field	Value
Publication number	US-10079321-B2
Application number	US-201615198795-A
Country	US
Kind code	B2
Filing date	Jun 30, 2016
Priority date	Jun 30, 2016
Publication date	Sep 18, 2018
Grant date	Sep 18, 2018

Abstract

Techniques for increasing grain size in AZTSSe absorber materials are provided. In one aspect, a method for forming an absorber film on a substrate includes: contacting the substrate with an Ag source, a Zn source, a Sn source, and an S source and/or an Se source under conditions sufficient to form the absorber film on the substrate having a target composition of: Ag X Zn Y Sn(S,Se) Z , wherein 1.7<x<2.2, 0.9<y<1.3, and 3.5<z<4.5, and including an amount of the Ag source that is from about 10% to about 30% greater than is needed to achieve the target composition; annealing the absorber film; and removing excess Ag from the absorber film. A solar cell and method for fabrication thereof are also provided.

First claim

What is claimed is:

1. A method for forming an absorber film on a substrate, comprising:
contacting the substrate with an Ag source, a Zn source, a Sn source, and at least one of an S source and an Se source under conditions sufficient to form the absorber film on the substrate having a target composition of: Ag X Zn Y Sn(S,Se) Z , wherein 1.7<x<2.2, 0.9<y<1.3, and 3.5<z<4.5, and including an amount of the Ag source that is from about 10% to about 30% greater than is needed to achieve the target composition;
annealing the absorber film; and
removing excess Ag, if any, from the absorber film, wherein the excess Ag forms a secondary phase, and wherein the removing is performed after the annealing to remove the secondary phase from grain boundaries of the absorber film.

2. The method of claim 1 , wherein the conditions comprise a temperature, a duration, and a pressure.

3. The method of claim 2 , wherein the temperature is from about 10° C. to about 450° C.

4. The method of claim 2 , wherein the duration is from about 1 minute to about 200 minutes.

5. The method of claim 2 , wherein the pressure is from about 1×10 −5 Torr to about 5×10 −10 Torr.

6. The method of claim 1 , wherein the annealing is performed at a temperature of from about 430° C. to about 550° C.

7. The method of claim 1 , wherein the annealing is performed for a duration of from about 20 seconds to about 10 minutes.

8. The method of claim 1 , wherein the secondary phase is selected from the group consisting of: Ag 2 Se, Ag 6 SnSe 8 , and combinations thereof.

9. The method of claim 1 , wherein the excess Ag is removed using an etchant selected from the group consisting of: potassium cyanide, sodium cyanide, and combinations thereof.

10. The method of claim 1 , wherein the absorber film has an average grain size of from about 0.5 micrometers to about 4 micrometers.

11. The method of claim 1 , further comprising:
measuring composition of the absorber film using Particle Induced X-ray Emission (PIXE) techniques.

12. A method of forming a solar cell, comprising:
contacting a conducting substrate with an Ag source, a Zn source, a Sn source, and at least one of an S source and an Se source under conditions sufficient to form the absorber film on the conducting substrate having a target composition of: Ag X Zn Y Sn(S,Se) Z , wherein 1.7<x<2.2, 0.9<y<1.3, and 3.5<z<4.5, and including an amount of the Ag source that is from about 10% to about 30% greater than is needed to achieve the target composition;
annealing the absorber film;
removing excess Ag, if any, from the absorber film, wherein the excess Ag forms a secondary phase, and wherein the removing is performed after the annealing to remove the secondary phase from grain boundaries of the absorber film;
forming a buffer layer on the absorber layer; and
forming a transparent front contact on the buffer layer.

13. The method of claim 12 , wherein the conditions comprise a temperature of from about 10° C. to about 450° C., a duration of from about 1 minute to about 200, and a pressure of from about 1×10 −5 Torr to about 5×10 −10 Torr.

14. The method of claim 12 , wherein the annealing is performed at a temperature of from about 430° C. to about 550° C., for a duration of from about 20 seconds to about 10 minutes.

15. The method of claim 12 , wherein the secondary phase is selected from the group consisting of: Ag 2 Se, Ag 6 SnSe 8 , and combinations thereof.

16. The method of claim 12 , wherein the excess Ag is removed using an etchant selected from the group consisting of: potassium cyanide, sodium cyanide, and combinations thereof.

17. The method of claim 12 , wherein the absorber film has an average grain size of from about 0.5 micrometers to about 4 micrometers.

Assignees

• IBM

Inventors

• Gershon Talia S
• Gordon Michael S
• Lee Yun Seog

Classifications

• H01L31/022475

  Electricity · mapped topic

• H01L31/18

  Electricity · mapped topic

• C01G19/006

  Compounds containing tin, with or without oxygen or hydrogen, and containing two or more other elements · CPC title

• H01L31/022483

  Electricity · mapped topic

• H01L31/02008

  Electricity · mapped topic