Deep levels of tantalum in silicon carbide and incorporation during crystal growth

Band-gap states of tantalum in n-type 6H- and 15R-silicon carbide (SiC) wer e investigated by deep-level transient spectroscopy (DLTS). The samples wer e doped with Ta by ion implantation followed by an annealing procedure. DLT S measurements reveal two implantation-induced band-gap states in each poly type. These donor-like levels (located at E-C-0.46 eV and E-C-0.49 eV in 6H - and E-C-0.43 eV and E-C-0.46 eV in 15R-SiC) are assigned to Ta occupying inequivalent lattice sites in the SiC crystals. The investigation of 6H-SiC bulk material grown in an atmosphere containing Ta indicates the incorpora tion of Ta in these crystals during growth. (C) 2001 American Institute of Physics.