Development of Sb2Te3 films for low-resistance contact to CdS/CdTe solar cells
Narrow band gap Sb2Te3 have been successfully deposited by electrochemical technique from aqueous solution containing Sb2O3, TeO2, NaOH and Tartaric acid at 60°C. The deposition potential was optimized to be −0.5 V with respect to Ag/AgCl reference electrode using cyclic voltammetry with slow scan 5 mV sec−1. Sb2Te3 films were heat treated at 400 °C for 20 minutes. As-deposited and annealed layers were characterized to study the structural, compositional and morphological properties. Hexagonal structure was identified for Sb2Te3 films. The improvement in the crystallinity and particles size was observed for the annealed films. Close to ideal stoichiometric films (40: 60) were deposited at growth potential −0.5 V, confirmed by Energy dispersive X-ray analysis (EDAX). Uniform, compact and mixed (needle and flack) morphology was observed by scanning electron microscopy (SEM). After heat treatment the flacks are converted into bigger grains.