Effect of rf-sputtered Mo substrate on the microstructure of electrodeposited CuInSe2 thin films

The effect of Mo substrate structure on the microstructure of electrodeposited CuInSe2 thin films has been investigated, r.f.-magnetron sputtered Mo layers have been prepared by varying sputtering time (20-70 min), r.f.-power density (1.8-7.5 W cm(-2)) and Ar mass-flow rate (80-140 sccm). The structure, surface morphology and optoelectronic properties of these Mo samples have been analysed before being used as substrates for direct electrodeposition of CuInSe2. The electrodeposited CuInSe2 on Mo has also been studied in the same way, as-grown and after selenization. A low r.f.-power density of about 2.4 W cm(-2) and a low Ar mass-how rate of about 80 seem have been selected as the appropriate deposition parameters to improve the Mo optical reflectance, R (400-800 nm)similar to 50%, maintaining rho=0.1-0.2 mu Omega m, by minimizing stresses and micropores and obtaining densely packed structures. The optimized Mo films are found to be suitable substrates for growing CuInSe2 by direct electrodeposition. These CIS-Mo bilayers have shown neither microstress nor micropores after annealing in a Se vapour atmosphere at temperatures as high as 500 degrees C, which are required to enhance the CuInSe2 recrystallization. (C) 1998 Elsevier Science S.A. All rights reserved.