Impact of rapid thermal annealing temperature on non-metallised polycrystalline silicon thin-film diodes on glass

Abstract

A rapid thermal annealing (RTA) process is performed to activate the dopants and anneal point defects in planar polycrystalline silicon (poly-Si) thin-film solar cell diodes on glass. The impact of the RTA peak temperature on the open-circuit voltage (Voc), the sheet resistance and the doping profiles of the non-metallised samples was investigated. An annealing temperature of about 1000°C was found to give the highest Voc and the lowest sheet resistance. The doping concentration was measured using the electrochemical capacitance voltage (ECV) method. The doping concentration was found to increase with increasing RTA temperature, before it decreased at high temperature. The junction depth was found to move away from the glass-side with increasing annealing temperature. The sheet resistances were calculated based on the ECV doping profiles and were found to have a trend similar to the experimental values obtained by the four-point probe method. The highest average Voc obtained in this work is 471mV and it corresponds to the lowest sheet resistance.