Comparison between large area dc-magnetron sputtered and e-beam evaporated molybdenum as thin film electrical contacts

Two different deposition techniques have been compared for obtaining large area Mo thin films as electrical back contacts in polycrystalline solar cells. The dc-magnetron sputtered layers have been made by varying dc-power (100-400 W), sputtering time (40-80 min) and Ar-mass flow rate (11-150 sccm) while e-beam evaporated Mo has been fabricated at several powers (1400-2000 W). Adequate optoelectronic, structural and morphological properties without stress have been achieved when intermediate Ar-mass flow rates are used during the sputtering process. Evaporated samples present higher electrical resistivity than sputtered ones but still valid for photovoltaic purposes. The 500-550degreesC heat treatments in Se atmosphere modify Mo features by an appearing MoO2 layer on its surface. (C) 2003 Elsevier Science B.V. All rights reserved.