Devices and methods featuring the addition of refractory metals to contact interface layers
View Patent ↗Disclosed embodiments include CdS/CdTe PV devices ( 100 ) having a back contact ( 110,112 ) with oxygen gettering capacity. Also disclosed are back contact structures ( 110, 112 ) and methods of forming a back contact in a CdS/CdTe PV device ( 100 ). The described contacts and methods feature a contact having a contact interface layer ( 100 ) comprising a contact interface material, a p-type dopant and a gettering metal.
1. A method comprising:
forming a sputtering target comprising a contact interface material, a dopant, and a non-oxide compound of a gettering metal;
depositing the sputtering target on to a CdTe device layer to form a contact interface layer comprising the contact interface material, the dopant and the non-oxide compound of the gettering material; and
depositing an outer metallization layer comprising the gettering metal to the contact interface layer; wherein:
the dopant diffuses into the CdTe device layer causing the CdTe device layer to become p-type,
the gettering metal diffuses into the contact interface layer from the outer metallization layer, and
the non-oxide compound of the gettering metal diffuses into the CdTe device layer.
2. The method of claim 1 wherein the non-oxide compound of the gettering metal exhibits a smaller negative enthalpy than a metal oxide of the gettering metal.
3. The method of claim 1 wherein the gettering metal is Ti, Zr, or Hf.
4. The method of claim 2 wherein the non-oxide compound of the gettering metal is TiTe 2 .
5. The method of claim 1 the contact interface material is ZnTe.
6. The method of claim 1 , wherein
the contact interface material, the dopant, and the non-oxide compound of the getting metal were pressed to form the sputtering target in an inert or reducing atmosphere; and
machining the sputtering target in an inert or reducing atmosphere.
7. The method of claim 1 further comprising depositing the contact interface layer in an inert or reducing atmosphere.
8. The method of claim 1 wherein the sputtering target comprises ZnTe, Cu, and the gettering metal.
9. The method of claim 8 wherein the gettering metal is Ti.
10. The method of claim 1 , wherein the dopant is a group IA species or a group VA species.
11. The method of claim 10 , wherein the dopant is Cu.