Hybrid density functional study of strain-engineered III–V semiconductors and monolayer InSe
Abstract
Accurate prediction of strain-dependent semiconductor properties requires reliable exchange–correlation treatments and a unified understanding of bulk and two-dimensional materials. Here, we investigate strain-engineered bulk AlP, AlSb, and monolayer InSe under biaxial strains from −6% to +6% using the Perdew–Burke–Ernzerhof (PBE) and Heyd–Scuseria–Ernzerhof (HSE06) functionals. HSE06 significantly improves structural accuracy, reducing the mean absolute deviation in lattice parameters from 1.47% to 0.39%. Biaxial strain lowers the symmetry of bulk AlP and AlSb from cubic zinc blende to tetragonal structures, whereas monolayer InSe retains its hexagonal symmetry. Phonon spectra and ab initio molecular dynamics confirm the stability of all materials, although monolayer InSe develops small imaginary phonon frequencies near the Γ-point under compressive strain. Thermodynamic properties remain insensitive to strain. Compressive strain increases the elastic stiffness of all three materials, whereas tensile strain reduces it. Elastic anisotropy increases under compression and decreases under tension in bulk AlP and AlSb, while monolayer InSe remains isotropic throughout the investigated strain range. HSE06 reproduces the experimental band gaps, revealing a tensile-induced indirect-to-direct band-gap transition in AlSb and a band-gap tunability of approximately 1.69 eV in monolayer InSe. Tensile strain redshifts the absorption edge, highlighting the potential of these materials for strain-engineered optoelectronic and flexible electronic devices.