The band-gap of Tl-doped gallium nitride alloys

Abstract

Structural and electronic properties of hypothetical zinc blende TlxGa1−xN alloys have been investigated from first principles. The structural relaxation, preformed within the LDA approach, leads to a linear dependence of the lattice parameter a on the Tl content x. In turn, band structures obtained by MBJLDA calculations are significantly different from the corresponding LDA results. The decrease of the band-gap in Tl-doped GaN materials (for x<0.25) is predicted to be a linear function of x, i.e. 0.08eV per atomic % of thallium. The semimetallic character is expected for materials with x>0.5. The obtained spin–orbit coupling driven splitting between the heavy-hole and split-off band at the Γ point of the Brillouin zone in TlxGa1−xN systems is significantly weaker when compared to that of Tl-doped InN materials.