Methods of forming a conductive transparent oxide film layer for use in a cadmium telluride based thin film photovoltaic device
View Patent ↗Methods are generally provided for forming a conductive oxide layer on a substrate. In one particular embodiment, the method can include sputtering a transparent conductive oxide layer on a substrate from a target (e.g., including cadmium stannate) in a sputtering atmosphere comprising cadmium. The transparent conductive oxide layer can be sputtered at a sputtering temperature of about 100° C. to about 600° C. Methods are also generally provided for manufacturing a cadmium telluride based thin film photovoltaic device.
1. A method for forming a conductive oxide layer on a substrate, the method comprising:
sputtering a target in a sputtering atmosphere to deposit a transparent conductive oxide layer on a substrate, wherein the target comprises cadmium stannate, and wherein the transparent conductive oxide layer is deposited at a sputtering temperature of about 100° C. to about 600° C.; and,
during sputtering, adding a cadmium gas source to the sputtering atmosphere to provide an increased amount of cadmium to the sputtering atmosphere than supplied by the target.
2. The method as in claim 1 , wherein the cadmium gas source comprises an organo-cadmium gas.
3. The method as in claim 1 , wherein the cadmium gas source comprises dimethyl cadmium.
4. The method as in claim 1 , wherein the sputtering atmosphere further comprises an inert gas.
5. The method as in claim 4 , wherein the inert gas is argon.
6. The method as in claim 1 , wherein the sputtering atmosphere further comprises oxygen.
7. The method as in claim 1 , wherein the sputtering atmosphere has a pressure of about 1 mTorr to about 100 mTorr.
8. The method as in claim 1 , wherein the cadmium gas source constitutes about 0.1% to about 25% by volume of the sputtering atmosphere.
9. The method as in claim 1 , wherein the cadmium gas source about 1% to about 15% by volume of the sputtering atmosphere.
10. The method as in claim 1 , wherein the transparent conductive oxide layer has a thickness of about 100 nm to about 1 μm.
11. The method as in claim 1 , wherein the transparent conductive oxide layer has a thickness of about 150 nm to about 400 nm.
12. The method as in claim 1 , wherein the sputtering temperature is about 150° C. to about 300° C.
13. The method as in claim 1 , wherein the sputtering temperature is about 175° C. to about 250° C.
14. The method as in claim 1 , wherein the cadmium gas source constitutes about 0.1% to about 25% by volume of the sputtering atmosphere.
15. A method for manufacturing a cadmium telluride based thin film photovoltaic device, the method comprising:
sputtering a target in a sputtering atmosphere to deposit a transparent conductive oxide layer on a substrate, wherein the target comprises cadmium stannate, and wherein the transparent conductive oxide layer is deposited at a sputtering temperature of about 100° C. to about 600° C.; and,
during sputtering, adding a cadmium gas source to the sputtering atmosphere to provide an increased amount of cadmium to the sputtering atmosphere than supplied by the target;
forming a resistive transparent buffer layer over the transparent conductive oxide layer;
forming a cadmium sulfide layer over the resistive transparent layer; and,
forming a cadmium telluride layer over the cadmium sulfide layer.
16. The method as in claim 15 , wherein the cadmium gas source comprises an organo-cadmium gas.
17. The method as in claim 15 , wherein the sputtering temperature is about 150° C. to about 300° C.
18. The method as in claim 15 , wherein the cadmium gas source comprises an organo-cadmium gas, the sputtering atmosphere further comprising an inert gas.
19. The method as in claim 18 , wherein the organo-cadmium gas comprises dimethyl cadmium.