Crystallization characteristics in heavily B2H6-doped amorphous Si thin films

Abstract

We have investigated the crystallization in amorphous silicon doped with B2H6 for varing doping levels under ɛ-field. Crystallization rate is classified into 3 stages based on the doping time, the mechanisms involved, and the rate determining step. The crystallization rate is saturated at around 10 μm/h after 2 min doping time. The main mechanism for the rate saturation is due to the high internal ɛ-field caused by the heavy doping. The direction of the internal ɛ-field in the case of p-type doping is opposite to that of n-type doping, which causes the final saturated crystallization rate to be higher in the case of p-type doping, and lower in the case of n-type doping, compared to the intrinsic a-Si. The B2H6-doped samples with an ɛ-field show an uni-directional needle network microstructure with a preferred orientation of <111> direction in (110) plane.