Voc improvement of evaporated SPC thin-film Si solar cells on glass by rapid thermal annealing

Rapid thermal processing has predominantly been developed for wafer-based devices yet also has great potential for low-temperature devices such as thin-film polycrystalline silicon (pc-Si) on glass solar cells. The present paper investigates the impact of rapid thermal annealing (RTA) on thin-film pc-Si solar cells on glass made by evaporation of a-Si and subsequent solid-phase crystallization (SPC). These devices are referred to by us as EVA cells (SPC of evaporated a-Si). RTA parameter variations are performed to determine optimum values for point defect removal and dopant activation, and to maximize the open-circuit voltage (V_oc). Upon hydrogenation in a RF PECVD hydrogen plasma, a 1-Sun V_oc of 443 mV is realized. Through optimization, a V_oc of 500 mV is clearly within the reach of the EVA technology.