Method of forming a buffer layer in a solar cell, and a solar cell formed by the method
A method of fabricating a buffer layer of a photovoltaic device comprises: providing a substrate having a back contact layer disposed above the substrate and an absorber layer disposed above the back contact layer; depositing a metal layer on the absorber layer; and performing a thermal treatment on the deposited metal layer in an atmosphere comprising sulfur, selenium or oxygen, to form a buffer layer.
1. A method of fabricating a buffer layer of a photovoltaic device comprising:
providing a substrate having a back contact layer disposed above the substrate and an absorber layer disposed above the back contact layer;
depositing a metal layer comprising cadmium or Zn 1-x Mg x on the absorber layer; and
performing a thermal annealing treatment on the deposited metal layer in an atmosphere comprising sulfur or oxygen gas to transform the deposited metal layer into a buffer layer.
2. The method of claim 1 , wherein the metal layer comprises cadmium, and the atmosphere comprises at least one of the group consisting of sulfur and H 2 S.
3. The method of claim 1 , wherein the atmosphere comprises at least one of the group consisting of sulfur and H 2 S.
4. The method of claim 1 , wherein the metal layer comprises Zn 1-x Mg x , and the atmosphere comprises oxygen.
5. The method of claim 1 , wherein the step of depositing a metal layer on the absorber layer includes depositing from 1 nm to 1000 nm of metal.
6. The method of claim 1 , wherein the step of depositing a metal layer on the absorber layer includes depositing from 5 nm to 500 nm of metal.
7. The method of claim 6 , wherein the buffer layer has a thickness in a range from 13 nm to 1300 nm.
8. The method of claim 1 , wherein the atmosphere further comprises an inert gas.
9. The method of claim 1 , wherein the thermal treatment is a rapid thermal anneal.
10. The method of claim 8 , wherein the thermal treatment is a rapid thermal anneal performed at a temperature from 300° C. to 600° C.
11. A method of fabricating a photovoltaic device comprising:
providing a substrate;
forming a back contact layer above the substrate;
forming a copper indium gallium diselenide (CIGS) absorber layer from a plurality of CIGS precursors above the back contact layer;
sputtering a metal layer on the CIGS absorber layer, the metal layer being an additional indium layer separate from the CIGS precursors ; and
performing a rapid thermal anneal on the deposited metal layer in an atmosphere comprising sulfur, to form a buffer layer; and
forming a front contact layer above the buffer layer.
12. The method of claim 11 , wherein the atmosphere comprises at least one of the group consisting of sulfur and H 2 S.
13. A method of fabricating a photovoltaic device comprising:
providing a substrate;
forming a back contact layer above the substrate;
forming an absorber layer above the back contact layer;
sputtering a metal layer on the absorber layer, the metal layer comprising cadmium; and
performing a thermal annealing treatment on the deposited metal layer in an atmosphere comprising sulfur gas, to form a buffer layer; and
forming a front contact layer above the buffer layer.
14. The method of claim 13 , wherein the atmosphere further comprises an inert gas.
15. The method of claim 1 , wherein the thermal treatment is a rapid thermal anneal.
16. The method of claim 11 , wherein the step of sputtering a metal layer on the absorber layer includes sputtering from 5 nm to 500 nm of metal.
17. The method of claim 11 , wherein the atmosphere further comprises an inert gas.
18. The method of claim 11 , wherein the rapid thermal anneal is performed at a temperature from 300° C. to 600° C.
19. The method of claim 13 , wherein the step of depositing a metal layer on the absorber layer includes depositing from 5 nm to 500 nm of metal.
20. The method of claim 15 , wherein the rapid thermal anneal is performed at a temperature from 300° C. to 600° C.