First-principles study of tunable GaTe/GaAs heterostructure: A promising material for high-performance photodetectors

A GaTe/GaAs van der Waals heterojunction (vdWH) was constructed via first-principles calculations, with systematic investigation of its structural, transport, and optoelectronic properties. Geometric structure calculations revealed that the GaTe/GaAs heterostructure is a typical type-II vdWH, which could effectively suppress the recombination of electron-hole pairs. The heterostructure's stability was comprehensively verified through binding energy calculations, phonon spectra, and ab initio molecular dynamics (AIMD) simulations, demonstrating favorable energetic, mechanical, and thermodynamic stability. Furthermore, Heyd-Scuseria-Ernzerhof (HSE06) functional calculations demonstrated an indirect bandgap of 0.87 eV for the GaTe/GaAs vdWH. And the vdWH exhibits exceptional anisotropic transport properties and tunable optoelectronic characteristics. Most notably, it demonstrated dramatically enhanced carrier mobilities compared to monolayer constituents: electron mobility reaches 7632.48 cm²V⁻¹s⁻¹(x-axis) and 80,995.84 cm²V⁻¹s⁻¹ (y-axis), while hole mobility peaks at 35,673.88 cm²V⁻¹s⁻¹ (x-axis) and 122,337.20 cm²V⁻¹s⁻¹ (y-axis), confirming strong directional transport advantages. Critically, the electronic structure showed high tunability by the external electric field and the strain engineering. These tailored electronic properties enable superior near-infrared (NIR) light absorption exceeding individual monolayers. Combined with its outstanding electrical characteristics and carrier mobility, the GaTe/GaAs vdWH emerges as a highly promising candidate for advanced NIR optoelectronic devices.