Influence of crystalline defects in Czochralski-grown Si multicrystal on minority carrier lifetime

Abstract

Si multicrystals have been grown by the Czochralski (CZ) method using commercially available semiconductor grade Si raw material (11N) and high purity silica crucibles for investigating the influence of crystalline defects such as grain boundaries including sub-grain-boundaries, and high-density dislocations on the minority carrier lifetime. The minority carrier lifetime in the CZ-Si multicrystal was compared with that in a CZ-Si single crystal, both with and without intentional Fe doping. It was found that the minority carrier lifetime in regions with high density of crystalline defects in the CZ-Si multicrystal decreased drastically to 1 μs from 8 μs, which was the value in the CZ-Si single crystal. Fe doping with a concentration of 3×10 13 atoms/cm 3 decreased the minority carrier lifetime to 2 μs in the CZ-Si single crystal. We therefore conclude that both crystalline defects and Fe doping play a very important role in the deterioration of the minority carrier lifetime, and the influence of the crystalline defects is more crucial by considering that the occurrence of crystalline defects in a multicrystal is an intrinsic problem whereas Fe contamination is an extrinsic one.