Preparation and Characterization of Molybdenum Thin Films by Direct-Current Magnetron Sputtering
The back contact electrode with molybdenum (Mo) thin film is crucial to the performance of Cu(In, Ga)Se2 solar cells. In this research, Mo thin films were fabricated by direct current sputtering to attain low-resistivity molybdenum films on soda-lime glass substrates with good adhesion. The films were sputtered onto substrates in 500 nm thickness and nominally held at room temperature with deposition conditions of power and working pressure. Low resistivity (17-25 μΩ∙cm) of bi-layer molybdenum thin films were achieved with combination of top layer films deposited at 300 W with different working pressure, and bottom fixing layer film deposited at 300 W with 2.5 mTorr which adhered well on glass. Films were characterized the electrical properties, structure, residual stress, morphology by using the Hall-effect Measurement, X-ray Diffraction, and Field-Emission Scanning Electron Microscopy, respectively, to optimize the deposition conditions.