The GaN/MgAl2S4 heterojunction: an excellent candidate material for photodetectors

Abstract

The GaN/MgAl₂S₄ heterojunction is constructed and investigated in this study. By constructing five different stacking structures of the GaN/MgAl₂S₄ heterojunction, the most stable stacking-IV structure is selected. Mechanical properties reveal that the GaN/MgAl₂S₄ heterojunction exhibits a tendency toward isotropy. Electronic structure calculations show that the GaN/MgAl₂S₄ heterojunction belongs to a type II heterojunction with an indirect band gap of 3.04 eV, and the built-in electric field effectively promotes photogenerated carrier separation. Photodetector simulations indicate that the device exhibits excellent peak response (0.818 a₀² per photon at 3.2 eV) under a photon energy of 3.2 eV and a polarization angle of 90°, with ultra-high polarization selectivity (extinction ratio of 222.25 at 4.0 eV). This study provides theoretical bases for designing a high-performance photodetector.