High-throughput first-principles investigation of GaN-AlN ternary system

• Published in: Superlattices and microstructures 2019-05, Vol.129, p.226-229
• Main Authors: Hadj Ahmed, H. Maiz, Zaoui, A., Ferhat, M.
• Format: Article
• Language: English
• Subjects: AlxGa1-xN alloys; Civil Engineering; Density functional theory (DFT); Engineering Sciences; Evolutionary algorithm; Optical band gap bowing; Projector-augmented wave pseudopotential scheme (PAW)
• ISSN: 0749-6036; 1096-3677
• DOI: 10.1016/j.spmi.2019.04.002

The ternary III-Nitride AlxGa1-xN ternary is one of the paradigm materials that have recently revolutionized lighting technology in the ultraviolet spectrum. A systematic investigation of the GaN-AlN system using ab initio evolutionary algorithm evidence that AlxGa1-xN alloys exist in ordered ground-state structure at ambient conditions. Cubic (AlGa3N4 (x = 0.25), Al3GaN4(x = 0.75)) and tetragonal (AlGaN2 (x = 0.5)) are found thermodynamically quite or nearly stable. Computed elastic constants and phonons show that these phases are mechanically and dynamically stable. Using state-of-the-art LDA-1/2 approach we determine the direct band gap bowing of AlGaN alloys. We found a downward bowing parameter of b∼1.39eV over the entire composition range. Furthermore the optical band gap bowing is found composition-dependent. For x = 0.5, our theoretical analysis divulges that chemical effects are the main factor leading to b parameter. •ab initio evolutionary algorithm shows that AlGaN have ordered ground-state structure.•AlGa3N4, Al3GaN4 and tetragonal AlGaN2 are found thermodynamically quite or nearly stable.•A band gap bowing is found for AlGaN Using state-of-the-art LDA-1/2 approach.•We found a downward bowing parameter of b∼1.39eV over the entire composition range.•Our theoretical analysis divulges that chemical effects are the main factor behind bowing.