Patent ID: 8241943

Claim:
A method of sodium doping in fabricating CIGS/CIS based thin film solar cells, the method comprising: providing a non-planar shaped substrate member, having a surface region, in a first chamber which includes at least one target, the shaped substrate member being configured through mechanical motions to allow the surface region to be exposed to the at least one target; forming a barrier layer over the surface region; forming a first electrode layer over the barrier layer; sputtering a sodium bearing layer over the first electrode layer, the sodium bearing layer including a first amount of a sodium species; forming a precursor layer over the sodium bearing layer, the precursor layer including at least a copper or copper-gallium layer followed by an indium layer, wherein a content ratio of copper/group III species being no larger than 1.0; loading the shaped substrate member into a second chamber; and subjecting the shaped substrate member to a thermal treatment process in the second chamber to an environment including a gas-phase selenium species followed by a gas-phase sulfur species with the selenium species being substantially removed, to form an absorber layer; wherein the gas-phase sulfur species comprises hydrogen sulfuride released into the second chamber after the selenium species is substantially removed from the second chamber before the temperature is further increased to about 500° C.