Electric field and strain-driven Janus graphene/Ga₂SX (X = Se, Te)/graphene heterostructure: performance optimization and innovative regulation

Abstract This study systematically investigated the intrinsic properties and external field regulation mechanisms of Janus-type Gr/Ga 2 SX/Gr heterostructures based on first-principles calculations. The construction of three models (A1–A3) was undertaken to analyze the thermodynamic stability and electronic structure. The analysis revealed that A2 (Gr/Ga 2 SSe/Gr) has the lowest binding energy and the best stability. Electronic properties indicate that under S/Se/Te atomic layer modulation, A3 exhibits semi-metallic behavior suitable for high-speed devices and transparent electrodes, while A1 and A2 are direct-bandgap semiconductors applicable to photodetection fields. The effects of shear strain regulation are particularly significant, as evidenced by the substantial broadening of the bandgap. For instance, under 2% shear strain, the bandgap of A1 increases to 0.486 eV, outperforming the regulation efficiency of biaxial strain and vertical electric fields. The built-in electric field facilitates carrier separation, and optical analysis reveals that A3 exhibits excellent absorption performance over a broad spectral range, making it suitable for photovoltaic devices. The present study offers theoretical guidance for strain-controlled strategies and performance design of ternary Janus heterojunctions.