Controlling oxygen concentration levels during processing of highly-reflective contacts

1. An optoelectronic semiconductor device having a contact prepared by the method comprising:

depositing a silver layer on a semiconductor surface of the optoelectronic semiconductor device to define an interface with the semiconductor surface;

after the silver layer is deposited, depositing one or more additional layers on the silver layer to form a metallic stack, at least one of the one or more additional layers comprising an oxygen-gettering metal;

introducing a predetermined dose of oxygen into the metallic stack;

diffusing a portion of the oxygen-gettering metal to the interface; and

diffusing a portion of the oxygen to the interface.

2. The device of claim 1 , wherein the oxygen-gettering metal is nickel.

3. The device of claim 1 , wherein the dose of oxygen is introduced by flowing a controlled amount of oxygen into an annealing chamber during the annealing step.

4. The device of claim 1 , wherein the oxygen is introduced by applying an oxygen- containing chemical onto the metallic stack.

5. The device of claim 1 , wherein the oxygen is introduced by applying an oxygen- depositing treatment onto the metallic stack.

6. The device of claim 1 , wherein the oxygen is introduced during a metal stack deposition step.

7. The device of claim 1 , wherein the metallic stack comprises a first silver layer, and at least a nickel layer formed on top of the silver layer.

8. The device of claim 7 , further comprising a second silver layer formed on top of the at least one nickel layer.

9. The device of claim 1 , further comprising controlling a timing and a rate of release of a controlled amount of the dose of oxygen.

10. The device of claim 1 , further comprising depositing a layer of titanium on top of the metal stack.

11. The device of claim 1 , wherein the semiconductor comprises a gallium and nitrogen-containing semiconductor material.

12. The device of claim 1 , further comprising performing an electrical measurement on the optoelectronic semiconductor device to determine effects of the oxygen dose.

13. The device of claim 1 , wherein the fraction of the oxygen-gettering metal and of the oxygen form a metal oxide at the at least one interface.

14. The device of claim 1 , wherein the diffusing a portion of the oxygen-gettering metal and diffusing a portion of the oxygen are performed in a single step.

15. The device of claim 14 , wherein the single step is an annealing step.

16. The device of claim 1 , wherein the diffusing a portion of the oxygen-gettering metal and diffusing a portion of the oxygen and introducing the oxygen are performed in a single step.

17. The device of claim 1 ,

wherein the optoelectronic semiconductor device comprises a gallium and nitrogen-containing semiconductor device;

wherein the oxygen-getting metal comprises nickel in a nickel layer;

wherein depositing one or more additional layers on the silver layer to form a metallic stack comprises depositing a second silver layer on the nickel layer; and

wherein diffusing the oxygen-gettering metal and diffusing the oxygen comprises annealing the device in an oxygen-containing ambient environment to introduce the predetermined dose of oxygen into the optoelectronic semiconductor device and to diffuse a portion of the nickel in the nickel layer and a portion of the oxygen through the silver layer to the interface.

18. An optoelectronic semiconductor device having a contact prepared by the method comprising:

(a) providing a gallium and nitrogen-containing semiconductor device;

after (a), (b) depositing a first silver layer on at least one surface of the semiconductor to define an interface with the semiconductor surface;

after (b),(c) depositing a nickel layer on the first silver layer;

after (c), (d) depositing a second silver layer on the nickel layer; and

after (d),(e) annealing the device in an oxygen-containing ambient environment to introduce a predetermined dose of oxygen into the optoelectronic semiconductor device and to diffuse at least a portion of nickel in the nickel layer and a portion of the oxygen through the first silver layer to the interface.

19. A method of preparing reflective and electrically conductive Ag-based contacts on an optoelectronic semiconductor device, comprising:

depositing a silver layer on a surface of the semiconductor device to define an interface with the semiconductor surface;

depositing a nickel layer comprising nickel on the silver layer;

lifting off a portion of the nickel layer and the silver layer using an oxygen-containing solvent; and

annealing the device in an oxygen-containing ambient environment to introduce a predetermined dose of oxygen into the optoelectronic semiconductor device and to diffuse at least a portion of the nickel and a portion of the oxygen through the silver layer to the interface.

20. The method of claim 19 , wherein the oxygen-containing solvent is acetone.

21. The method of claim 19 , wherein the acetone is sprayed on the semiconductor device.