Electron-paramagnetic-resonance studies of defects in electron-irradiated p-type 4H and 6H SiC

Defects in p-type 4H and 6H SiC irradiated by 2.5 MeV electrons were studie d by electron paramagnetic resonance (EPR). Two anisotropic EPR spectra, la beled I and II, were observed in both 4H and 6H SIG. These spectra demonstr ating triclinic symmetry of the center can be described by an effective ele ctron spin S = 1/2. The angle alpha, between the direction of the principal g(z) of the g-tensors and the c-axis is determined as 63 degrees and 50 de grees for spectra I and II, respectively. In the 6H polytype, a third also similar EPR spectrum was detected. Based on their similarity in the electro nic structure (electron spin, symmetry, g values), annealing behavior and t emperature dependence, these spectra are suggested to be related to the sam e defect occupying different inequivalent lattice sites in 4H and 6H SiC. A pair between a silicon vacancy and an interstitial is a possible model for the defect. (C) 1999 Elsevier Science B.V. All rights reserved.