Effect of Thermal Annealing on Light-Induced Minority Carrier Lifetime Enhancement in Boron-Doped Czochralski Silicon**Supported by the National Natural Science Foundation of China under Grant No 61076056.

Abstract

The effect of thermal annealing on the light-induced effective minority carrier lifetime enhancement (LIE) phenomenon is investigated on the p-type Czochralski silicon (Cz-Si) wafer passivated by a phosphorus-doped silicon nitride (P-doped SiNx) thin film. The experimental results show that low temperature annealing (below 300°C) can not only increase the effective minority carrier lifetime of P-doped SiNx passivated boron-doped Cz-Si, but also improve the LIE phenomenon. The optimum annealing temperature is 180°C, and its corresponding effective minority carrier lifetime can be increased from initial 7.5 μs to maximum 57.7 μs by light soaking within 15 min after annealing. The analysis results of high-frequency dark capacitance-voltage characteristics reveal that the mechanism of the increase of effective minority carrier lifetime after low temperature annealing is due to the sharp enhancement of field effect passivation induced by the negative fixed charge density, while the mechanism of the LIE phenomenon after low temperature annealing is attributed to the enhancement of both field effect passivation and chemical passivation.