Boron acceptor levels in 6H-SiC bulk samples

Thermal admittance spectroscopy has been used to determine the ground-state energies of the boron impurity in 6H-SiC. The background doping, N-A-N-D, of the samples used in this study ranged from 3x10(16) to 1x10(18) cm(-3). From electron spin resonance studies, it is known that boron substitutes for silicon in the silicon carbide lattice occupying three inequivalent sites. Using admittance spectroscopy the ground state energies of E-v+0.27 eV, E-v+0.31 eV, and E-v+0.38 eV were determined for the shallow boron acceptor in 6H-SiC. The free carrier concentration does not appear to be the only determining factor for which the boron acceptor level is observed. (C) 1997 American Institute of Physics.