Relationship between defects induced by irradiation and reduction of hole concentration in Al-doped 4H-SiC

摘要

From the temperature dependence of the hole concentration in lightly Al-doped 4H-SiC epilayers, a shallow acceptor with Ev + 0.2 eV, which is an Al atom (Al-si) at a Si sublattice site, and an unknown deep defect with Ev + 0.35 eV are found, where Ev is the valence band maximum. In unirradiated epilayers, moreover, the density (N-Defect) of this defect is close to the Al acceptor density (N-A1)With irradiation of 0.2 MeV electrons, the NAI is reduced, while the N-Defect is increased. Judging from the minimum electron energy required to displace a substitutional C atom (C-s) or Alsi, the bond between Alsi and its nearest neighbor C, is broken due to the displacement of the C, by this irradiation. Moreover, the displacement of the C-s results in the creation of a complex (Al-si-V-C) of Alsi and its nearest neighbor C vacancy (V-C), indicating that the possible origin of the defect with Ev + 0.35 eV is Al-si -V-C. (c) 2005 Elsevier B.V. All rights reserved.