CdS and CdTe large area thin films processed by radio-frequency planar-magnetron sputtering

The processing of large area thin films solar cells represents a challenge, mainly due to the need for optimal setting of the critical growth parameters for scaling-up of the processes that guarantee homogeneous properties in the sub-minimodule architecture. We have been working with a Radio-Frequency Planar Magnetron Sputtering (RF-PMS) system, processing 450 cm² areas of CdS and CdTe thin films grown on soda lime glasses and conducting glasses (SnO₂:F-7Ω/ ) for CdS, using for it a 6″ balanced gun. The films have been processed with substrate temperatures (T_s) of 250°C, Ar chamber-pressure of 20 mTorr, and radio frequency power of 300 watts. The films were characterized by morphological, optical and electrical techniques, presenting in this work the corresponding measurements. Our results show that the better polycrystalline perfection, adherence and pinhole free films are obtained at substrate temperatures of 250°C.