The influence of CdTe growth ambient on MOCVD grown CdS/CdTe photovoltaic cells

Abstract CdS/CdTe photovoltaic cells have been grown by MOCVD (metal–organic chemical vapour deposition) with a range of VI/II ratios in the CdTe reactant mixture. All CdTe layers were highly doped with As (approx. 2×1018 atoms/cm3) to ensure p-type conductivity. Cell characteristics were measured in the as-grown state, without ex-situ CdCl2 or annealing treatments. The VI/II ratio, determined by the ratio of the organometallic concentrations, strongly affects cell performance, with a peak in photocurrent occurring at Te/Cd at approximately 0.6. An increase in growth temperature from 320 to 350°C more than doubles the efficiency at this VI/II ratio. An exponential-type relationship between the photocurrent and series resistance is apparent at each growth temperature.