Molybdenum thin films are widely used as the back electrode for copper indium gallium selenide solar cells. In this paper, the crystal structures and electrical and mechanical properties of Mo thin films were studied as a function of working gas pressure. It was found that the numerous micro-voids appearing in the surface of the Mo thin film deposited at high working gas pressure could be attributed to the low kinetic energy of sputtered atoms on the glass substrate. In addition, Mo thin films with large grain sizes and better crystallinity can also be obtained in the low working gas pressure owing to the high diffusivity of Mo atoms on the glass substrate. The residual stress of Mo thin film changed from compressive stress to tensile stress when the working gas pressure was increased from 2·5 to 15 mTorr. The electrical resistivity of Mo thin films increased monotonously with working gas pressure. This can be explained by the increase in the number of grain boundaries and micro-voids in the Mo thin film deposited at high working gas pressure, which alleviate grain boundary scattering and increase the carrier lifetime.
