A DFT study on physical properties of III–V compounds (AlN, GaN, AlP, and GaP) in the P3121 phase

Abstract

In this work, four III-V compounds in the P 3 _1 21 phase are proposed. Based on density functional theory (DFT), their structures, stability, and mechanical, anisotropic, electronic and optical properties were investigated in detail. P 3 _1 21-AlN/GaN/AlP/GaP are all proven to have dynamic and mechanical stability based on their elastic constants and phonon spectra. The calculated Vickers hardness shows that P 3 _1 21-AlN and P 3 _1 21-GaN possess high hardness values of 18.7 GPa and 18.1 GPa, respectively. The anisotropic properties reveal that all these materials exhibit obvious elastic anisotropy. In the P 3 _1 21 phase, AlN, GaN, and GaP are direct semiconductor materials, whereas AlP is an indirect semiconductor material, with calculated energy bandgaps of 4.51 eV ( P 3 _1 21-AlN), 2.36 eV ( P 3 _1 21-GaN), 1.84 eV ( P 3 _1 21-GaP), and 2.01 eV ( P 3 _1 21-AlP). In addition, P 3 _1 21-AlP has high photoelectron absorption. The calculated energy bandgaps and mechanical and optical properties suggest that P 3 _1 21-AlN/GaN/AlP/GaP may possess great potential to become high-performance materials in the electronics manufacturing industry.

Keywords

• density functional theory
• III–V polymorphs
• mechanical properties
• anisotropic properties
• electronic properties
• optical absorption