Structural and electronic properties of wurtzite GaX (X = N, P, As, Sb, Bi) under in-plain biaxial strains

• The structural and electronic properties of GaX (X = N, P, As, Sb, Bi) are studied.
• The influence of in-plane biaxial strain on GaX thin films is investigated.
• The typical wurtzite transfers to pseudographitic phases under large tensile strain.
• The variations in band gap as a function of in-plane biaxial strain are studied.
• These results give a good understanding of strain-based GaX epitaxial films.

Using first-principles density functional theory, we have investigated the structural and electronic properties of GaX (X = N, P, As, Sb, Bi) systems under in-plain biaxial strains. All GaX systems transfer from the typical wurtzite to pseudographitic phases when the in-plane tensile strains are large enough. Our findings indicate that the elastic stiffness coefficients have a direct correlation with the strains. The variations of the band gap energy are diverse with respect to the compressive and tensile biaxial strains. For tensile biaxial strains, the band gap decreases substantially as the increasing of the strains. Upon compressive biaxial strains, the band gap initially increases, and then undergoes a decline. In addition, we find that there exists an indirect to direct band gap transition of GaP at certain in-plane biaxial strains. These results give a good understanding of strain-based GaX series heteroepitaxy thin films.