Spatial distribution of the electronic wave function of the shallow boron acceptor in 4<i>H</i>- and 6<i>H</i>-SiC

Abstract

A high-frequency (95 GHz) pulsed electron paramagnetic resonance and electron-nuclear-double-resonance study has been carried out on the shallow boron acceptor in ${}^{13}\mathrm{C}$-enriched $4H\ensuremath{-}\mathrm{SiC}$ and $6H\ensuremath{-}\mathrm{SiC}.$ From the hyperfine interaction of the unpaired electron spin with the ${}^{13}\mathrm{C}(I=1/2)$ nuclei the spatial distribution of the electronic wave function has been established. It is found that there are subtle differences in the degree of localization of this wave function between the different sites (two quasicubic and one hexagonal) in the two polytypes $4H\ensuremath{-}\mathrm{SiC}$ and $6H\ensuremath{-}\mathrm{SiC},$ though only for the two quasicubic sites a complete study of the wave function could be made. In particular it is found that the spatial distribution is highly anisotropic. This anisotropy can be rationalized by considering the anisotropy of the hole mass, i.e., by assuming that effective-mass theory is (partly) valid in describing the remote part of the spatial distribution of the electronic wave function.