Exploration of n- and p-type doping for two-dimensional gallium nitride: charged defect calculation with first principles

Abstract

The calculation of charge transition energy level (CTL) and defect formation energy are of significance to explore potential n-type or p-type doping in materials. Based on the first-principles method, this paper systematically studied the structural, magnetic, and defect properties of 12 kinds of dopants in the two-dimensional hexagonal gallium nitride (2D h-GaN) system. The results show that the most stable charge states (MSCSs) for n-type systems are 0 and 1+, and all the n-type substitutes act as shallow donors. The MSCSs of the p-type systems are 1−, 0 and 1+, and the acceptor ionization energy is distributed higher than the valence band maximum (VBM) from ~1.25 to 2.85 eV, acting as deep acceptors, which will capture electrons (holes) in n-(p-type) 2D h-GaN and affect the carrier conductivity. Thus, it is difficult to achieve p-type doping through a single defect in 2D h-GaN, and complex defects are necessary to achieve p-type doping experimentally.