Substrate heating effects on properties of CdS thin films prepared by thermal evaporation for photovoltaic applications

Cadmium sulfide (CdS) thin films were prepared by simple thermal evaporation at different substrate temperatures. Increasing the substrate temperature during CdS deposition led to a significant increase in the CdS film resistivity due to a reduction in carrier concentration and degradation in the carrier mobility. SEM results showed that high substrate temperature yielded large grain size of CdS films. In n-CdS/p-CdTe heterojunction solar cells fabricated employing CdS films deposited at different substrate temperatures, efficiency was found to decrease due to a reduction in open-circuit voltage (V_oc) and fill-factor (FF) affected by high substrate temperature during deposition of CdS films.