The band-gap of Tl-doped gallium nitride alloys

TL;DR

This study uses first-principles calculations to explore the structural and electronic properties of hypothetical Tl-doped GaN alloys, revealing a linear band-gap decrease with Tl content and potential semimetallic behavior at higher doping levels.

Contribution

It provides the first theoretical analysis of Tl-doped GaN alloys, predicting their structural and electronic properties and the impact of thallium doping on the band-gap and semimetallic transition.

Findings

Band-gap decreases linearly with Tl content (0.08 eV per atomic %).

Lattice parameter varies linearly with Tl doping.

Semimetallic behavior predicted for x>0.5.

Abstract

Structural and electronic properties of hypothetical zinc blende Tl(x)Ga(1-x)N 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. 0.08 eV 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 Gamma point of the Brillouin zone in Tl(x)Ga(1-x)N systems is significantly weaker when compared to that of Tl-doped InN materials.