Order Structures of AlxGa1–xN Alloys: First-Principles Predictions

Abstract

Using first-principles evolutionary methodology for structure predictions, we investigated the structures properties of AlxGa1–xN alloys with different Al concentration. Seven unreported and low-energy order structures have been found successfully by enthalpy calculations. Especially for the structure of Al0.5Ga0.5N alloy, the eligible distribution of Ga and Al atoms makes the structure more stable than regular order, suggested previously due to less net strain. The relative distribution mechanism of Ga and Al atom has also been discussed. All predicted structure parameters agree well with recent experimental results [ACS Nano2011, 5, 1291]. The low formation enthalpies and spinodal decomposition temperature have been studied, which indicate high self-adapting stability of these predicted AlxGa1–xN alloys above 95K. In addition, the continuous bandgaps and similar absorption spectrums of these AlxGa1–xN alloys show that the optoelectronic properties can be easily tuned by varying the Al concentration in A...