TOWARD QUALITY IMPROVEMENT OF ELECTRODEPOSITED HARD METAL Mo/Cu COATINGS: SUITABILITY FOR CIGS SOLAR CELL APPLICATIONS

Bright and thick molybdenum (Mo) coatings with good purity and adhesion were electrodeposited on Copper (Cu)-supported Mo/Cu, which is based on aqueous bath containing molybdate ions. All the electrodeposition process was carried out at a fixed duration of 1200s, according to five different current densities 400, 450, 500, 550, and 600mA/cm2 at room temperature 25±1∘C. Metallic Mo deposits structure may correspond to that of body-centered cubic (bcc) structure. The lattice parameter, residual stress, crystallites size, micro-strain, and dislocation densities were inferred from Mo (110) texture. Synthetized Mo coatings have relatively same rough surface morphology (50–60nm) characterized by some superficial cracks, small uniform grain size having change less than 14%, low residual stress and a good adhesion, a good conductivity, and an appropriate purity that has reached 94 (Mo %wt.). We have deduced that structural and electrical properties of Mo deposits did not obey the existing cracks at surfaces. One important result was that the most cracked and unstressed coating obtained at 450mA/cm2 was the same coating having the best purity (Mo %wt.), the best conductivity, and highest free electrons mobility. We suggest that appearance of cracks is closely related to electrochemical facts such as the deposition rate and hydrogen evolution reaction process since cracks decrease beyond 450mA/cm2. A good correlation between each investigated property was, also, established and discussed.