Impact of metastable phases on electrical properties of Si with different doping concentrations after processing by high-pressure torsion

Si (100) wafers with various doping levels were subjected to high-pressure torsion (HPT). The resistivities for all doping levels increased by one or two orders of magnitude after initial compression, but then decreased after 10 revolutions of HPT processing to similar to 0.1 Omega cm for normally and heavily doped samples, and to similar to 0.02 Omega cm for the ultraheavily doped sample. After annealing at 873 K, the resistivities increased by four orders of magnitude compared to the original Si wafers. These results indicate that the formation of metastable phases plays an important role in the electrical resistivities of HPT-processed samples. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.