Surface passivation for CdTe devices

Patent metadata

Field	Value
Publication number	US-9722111-B2
Application number	US-201514615282-A
Country	US
Kind code	B2
Filing date	Feb 5, 2015
Priority date	Feb 6, 2014
Publication date	Aug 1, 2017
Grant date	Aug 1, 2017

Abstract

In one embodiment, a method for surface passivation for CdTe devices is provided. The method includes adjusting a stoichiometry of a surface of a CdTe material layer such that the surface becomes at least one of stoichiometric or Cd-rich; and reconstructing a crystalline lattice at the surface of the CdTe material layer by annealing the adjusted surface.

First claim

What is claimed is:

1. A method for surface passivation, the method comprising:
adjusting a stoichiometry of a surface of a CdTe material layer such that the surface becomes Cd-rich; and
reconstructing a crystalline lattice at the surface of the CdTe material layer by annealing the adjusted surface.

2. The method of claim 1 , further comprising:
applying an oxidizing etch to the surface of the CdTe material layer prior to adjusting the stoichiometry of the surface.

3. The method of claim 2 , wherein applying the oxidizing etch comprises applying an oxidizing agent including at least one of Bromine/Methanol (Br/MeOH);
nitric/phosphoric acid (NP); mixtures of acetic, nitric and sulfuric acid; ferric chloride; mixtures of nitric acid and potassium dichromate; or mixtures of nitric acid, potassium dichromate and CuNO 3 .

4. The method of claim 1 , wherein adjusting the stoichiometry of the surface of the CdTe material layer comprises applying a reducing etch to the surface of the CdTe material layer.

5. The method of claim 4 , wherein applying the reducing etch comprises applying a reducing agent including at least one of a basic salt, an alkali or alkaline material, hydrazine, potassium hydroxide (KOH), sodium hydroxide (NaOH), or mixtures of NaOH and sodium dithionite (Na 2 S 2 O 4 ).

6. The method of claim 1 , wherein adjusting the stoichiometry of the surface of the CdTe material layer comprises bombardment etching the surface of the CdTe material layer.

7. The method of claim 6 , wherein the bombardment etching comprises either sputter etching or plasma etching.

8. The method of claim 1 , further comprising:
forming a contact layer on the adjusted surface.

9. The method of claim 8 , wherein forming the contact layer on the adjusted surface comprises:
forming a contact interface layer on the adjusted surface; and
forming a metallization layer on the contact interface layer;
wherein the contact interface layer has band alignment with a material of the CdTe material layer.

10. The method of claim 1 , further comprising:
forming a heterocouple layer on the adjusted surface.

11. The method of claim 1 , wherein the stoichiometry of the adjusted surface is further adjusted by the annealing of the adjusted surface.

12. A method for surface passivation, the method comprising:
adjusting a stoichiometry of a surface of a CdTe material layer such that the surface becomes at least one of stoichiometric or Cd-rich; and
reconstructing a crystalline lattice at the surface of the CdTe material layer by annealing the adjusted surface,
wherein adjusting the stoichiometry of the surface of the CdTe material layer comprises applying a reducing etch to the surface of the CdTe material layer.

13. The method of claim 12 , further comprising:
applying an oxidizing etch to the surface of the CdTe material layer prior to adjusting the stoichiometry of the surface.

14. The method of claim 13 , wherein applying the oxidizing etch comprises applying an oxidizing agent including at least one of Bromine/Methanol (Br/MeOH);
nitric/phosphoric acid (NP); mixtures of acetic, nitric and sulfuric acid; ferric chloride; mixtures of nitric acid and potassium dichromate; or mixtures of nitric acid, potassium dichromate and CuNO 3 .

15. The method of claim 12 , wherein applying the reducing etch comprises applying a reducing agent including at least one of a basic salt, an alkali or alkaline material, hydrazine, potassium hydroxide (KOH), sodium hydroxide (NaOH), or mixtures of NaOH and sodium dithionite (Na 2 S 2 O 4 ).

16. The method of claim 12 , wherein adjusting the stoichiometry of the surface of the CdTe material layer comprises adjusting the stoichiometry of the surface of the CdTe material layer to stoichiometric.

17. The method of claim 12 , wherein adjusting the stoichiometry of the surface of the CdTe material layer comprises adjusting the stoichiometry of the surface of the CdTe material layer to Cd-rich.

18. The method of claim 12 , further comprising:
forming a contact layer on the adjusted surface.

19. The method of claim 18 , wherein forming the contact layer on the adjusted surface comprises:
forming a contact interface layer on the adjusted surface; and
forming a metallization layer on the contact interface layer;
wherein the contact interface layer has band alignment with a material of the CdTe material layer.

20. The method of claim 12 , further comprising:
forming a heterocouple layer on the adjusted surface.

21. The method of claim 12 , wherein the stoichiometry of the adjusted surface is further adjusted by the annealing of the adjusted surface.

Assignees

• Alliance Sustainable Energy

Inventors

• Reese Matthew O
• Perkins Craig L
• Burst James M
• Gessert Timothy A
• Barnes Teresa M
• Metzger Wyatt K

Classifications

• H10P14/3432

  Tellurides · CPC title

• H10P14/38

  characterised by treatments done after the formation of the materials · CPC title

• H01L31/1828

  Electricity · mapped topic

• H01L31/0296 Primary

  Electricity · mapped topic

• Y02E10/543

  Solar cells from Group II-VI materials · CPC title