Structural stability, tunable electronic and optical properties of two-dimensional WS2 and GaN heterostructure: First-principles calculations

Based on first-principles calculations, we explore the structural, electronic and optical properties of WS2/GaN heterostructure and its response to strain. Calculations reveal that in-plane compressive strain of 1% can cause the structural instability of WS2/GaN heterostructure while the tensile strain can retain the stability of structure. Under the tensile strain of 10%, the direct bandgap of the WS2/GaN heterostructure can be tuned significantly and its type-II nature of band alignment is preserved. The band offsets at the WS2-GaN interface coupled with the interlayer polarized field can effectively reduce the recombination of the photoinduced electron-hole pairs. Also, the increasing biaxial tensile strain can rouse the optical absorption for near-infrared light, widening the light harvesting of the WS2/GaN heterostructure. In addition, vertical strain can also engineer the electronic properties and optical absorption of the WS2/GaN heterostructure by changing the interlayer coupling. These results indicate that the WS2/GaN heterostructure has potential applications in optoelectronics.