Effects of Mg and Al doping on dislocation slips in GaN

Abstract

First-principles density functional theory calculations were employed to systematically examine the effects of Mg and Al additions to wurtzite GaN on the generalized stacking fault energy (GSFE) curves for (11¯00)[112¯0] and (11¯00)[0001] dislocations along the glide or shuffle slip planes. It was found that for both slip systems, Mg doping leads to significant reduction of the GSFE while Al doping elevates the GSFE curve. For each dopant, the effect of doping on the GSFE was shown to scale linearly with the dopant concentration, being independent of the slip (i.e., glide or shuffle) plane. The GSFE curves were subsequently combined with the Peierls-Nabarro model to quantitatively analyze the micromechanical characteristics of dislocation slips. The implications of our findings to slip dynamics and dislocation dissociation mechanism were then discussed. Our study provides important insights towards the understanding and control of dislocation dynamics in impurity-doped GaN.