Devices and methods of protecting a cadmium sulfide for further processing
View Patent ↗Methods for protecting a cadmium sulfide layer on a substrate are provided. The method can include sputtering a cadmium sulfide layer onto a substrate from a cadmium sulfide target at a sputtering pressure (e.g., about 10 mTorr to about 150 mTorr), and sputtering a cap layer directly on the cadmium sulfide layer. The cap layer can be sputtered directly onto the cadmium sulfide layer without breaking vacuum of the sputtering pressure. Methods are also provided for manufacturing a cadmium telluride based thin film photovoltaic device through depositing a cadmium sulfide layer on a substrate, depositing a cap layer directly on the cadmium sulfide layer, heating the substrate to sublimate at least a portion of the cap layer from the cadmium sulfide layer, and then depositing a cadmium telluride layer on the cadmium sulfide layer. An intermediate substrate for forming a cadmium telluride based thin-film photovoltaic device is also provided.
1. A method of protecting a cadmium sulfide layer for further processing, the method comprising:
sputtering a cadmium sulfide layer onto a substrate from a cadmium sulfide target at a sputtering pressure;
sputtering a cap layer directly on the cadmium sulfide layer without breaking vacuum of the sputtering pressure, wherein the cap layer comprises cadmium telluride;
heating the substrate to sublimate at least a portion of the cap layer from the cadmium sulfide layer; and,
thereafter, depositing a cadmium telluride layer on the cadmium sulfide layer.
2. The method as in claim 1 , wherein the cap layer is sputtered directly onto the cadmium sulfide layer from a cadmium telluride target.
3. The method as in claim 1 , wherein the sputtering pressure is about 1 mTorr to about 20 mTorr.
4. The method as in claim 1 , wherein the cadmium sulfide layer and the cap layer are sputtered in a sputtering atmosphere comprising an inert gas.
5. The method as in claim 4 , wherein the sputtering atmosphere further comprises oxygen from greater than 0% to about 20% by volume.
6. The method as in claim 1 , wherein the cap layer is sputtered at a sputtering temperature below the sublimation temperature of the cadmium sulfide layer.
7. The method as in claim 1 , wherein the cap layer is sputtered to a thickness of about 10 nm to about 150 nm.
8. A method of protecting a cadmium sulfide layer for further processing, the method comprising:
sputtering a cadmium sulfide layer onto a substrate from a cadmium sulfide target at a puttering pressure;
sputtering a cap lam directly on the cadmium sulfide layer without breaking vacuum of the sputtering pressure, wherein the cap layer comprises cadmium telluride, wherein the cap layer is sputtered from a cadmium telluride target to have a substantially vertical orientation of its primary axis;
heating the substrate to sublimate at least a portion of the cap layer from the cadmium sulfide layer; and,
thereafter, depositing a cadmium telluride layer on the cadmium sulfide layer.
9. The method as in claim 1 , wherein the cap layer is completely sublimed to expose the cadmium sulfide layer such that the cadmium telluride layer is deposited directly on the cadmium sulfide layer.
10. The method as in claim 1 , wherein the cap layer is sublimed to leave a portion of the cap layer between the cadmium sulfide layer and the cadmium telluride layer.
11. The method as in claim 1 , wherein the substrate is heated to a deposition temperature of about 250° C. to about 650° C. to sublimate at least a portion of the cap layer.
12. The method as in claim 1 , wherein both the cadmium sulfide layer and the cap layer are deposited via sputtering at a sputtering temperature of less than about 50° C.
13. The method as in claim 1 , wherein the cadmium telluride layer is deposited on the cadmium sulfide layer via closed space sublimation.
14. The method as in claim 8 , wherein the sputtering pressure is about 1 mTorr to about 20 mTorr.
15. The method as in claim 8 , wherein the cadmium sulfide layer and the cap layer are sputtered in a sputtering atmosphere comprising an inert gas.
16. The method as in claim 15 , wherein the sputtering atmosphere further comprises oxygen from greater than 0% to about 20% by volume.
17. The method as in claim 8 , wherein the cap layer is sputtered at a sputtering temperature below the sublimation temperature of the cadmium sulfide layer.
18. The method as in claim 8 , wherein the cap layer is sputtered to a thickness of about 10 nm to about 150 nm.
19. The method as in claim 8 , wherein the cadmium telluride layer is deposited on the cadmium sulfide layer via closed space sublimation.