Electronic Structure of Beryllium, Magnesium and Silicon Impurity in Cubic Gallium Nitride

Abstract

AbstractBeryllium (Be), magnesium (Mg) and silicon (Si) impurities in zinc-blende galliumnitride (c-GaN) are investigated by the tight binding-linear combination muffin-tin orbitals (TBLMTO) method using a 64-atom supercell. Be and Mg impurities at a Ga site, respectively induce partially empty acceptor-like bands at the valence band edge, which result in p-type conductivity of doped c-GaN. Si impurity in the Ga sublattice creates a partially occupied impurity subband overlapping with the conduction band edge and is responsible for the measured n-type conductivity. The impurity levels of a Si at a N site are located deep in the gap and do not influence much the conductivity of c-GaN. The shell-projected, total and partial densities of states and the charge density maps are used to elucidate the energy and spatial localizations of the impurity states