Abstract: Improved thin-film photovoltaic devices and methods of manufacturing such devices are described. Embodiments include a substrate-configured thin-film PV device (200) having a photo-absorbing semiconductor layer (230) and a window layer (240). Embodiments include devices having a CdTe photo-absorbing semiconductor layer, a CdS or CdS:In window layer, and an n-p junction residing at or proximate an interface of the photo-absorbing semiconductor and window layers. Variations include methods of manufacture wherein i) O2 is excluded from an ambient environment during deposition of the CdTe layer (102), ii) O2 is included in an ambient environment during CdCl2 treatment (103), iii) O2 is included in an ambient environment during deposition of a CdS or CdS:In layer (104), or iv) a medium-temperature anneal (MTA) having an anneal temperature of 300° C. or less is performed (105) after deposition of the CdS layer.

Abstract: A method for making a heterojunction photovoltaic device (200) is provided for converting solar radiation to photocurrent and photovoltage with improved efficiency. The method and apparatus include an improved window layer (230) having an increased oxygen (140) concentration with higher optical bandgap and photo to dark conductivity ratio. The improved photovoltaic device (200) is made using a deposition method which incorporates the use of a gas mixture of an inert gas (115) and a predetermined amount of oxygen (140), deposited at or near room temperature. Window layers contemplated by the present invention include, but are not limited to, cadmium sulfide (CdS) and various alloys of zinc cadmium sulfide (ZnxCd1-xS). To further increase the efficiency of the resultant photovoltaic device (200), deposition parameters are controlled and monitored to improve the deposited window layer (230).