Low-resistivity Mo thin films prepared by evaporation onto 30 cm×30 cm glass substrates

In order to obtain a suitable back contacting material for CuInSe2-based photovoltaic devices, molybdenum thin films have been deposited onto glass substrates up to 30 cm×30 cm area using an electron beam evaporator. In the CuInSe2-based devices, molybdenum has to provide the electrical properties of a low-resistivity electrode and must also serve as a part of the substrate during the growth of successive photovoltaic components, maintaining chemical and mechanical stability during the whole device fabrication process. Film thickness, sheet resistance, optical reflectance and surface roughness measurements have been performed for the Mo layers prepared at various deposition power and time. The film microstructure, such as the preferred orientation and the residual intrinsic stress, has been determined by X-ray diffraction. The electrical requisites for photovoltaic applications have been achieved for Mo layers evaporated at different experimental conditions with similar homogeneity over the substrate area. On the other hand, the intrinsic stress in Mo films has been found depending on the evaporation parameters, mainly on the thin-film deposition rate.