Interface-controlled band alignment transition and optical properties of Janus MoSSe/GaN vdW heterobilayers

Since the Janus MoSSe monolayer was fabricated in 2017, it has attracted increasing attention because the out-of-plane mirror symmetry is broken. Here, based on first-principles calculations, we construct theoretically 2D Janus MoSSe/GaN van der Waals (vdW) heterobilayers, and demonstrate that it has direct band structure and a broad optical absorption spectrum from visible to the UV region. Interestingly, the S- and Se-interface can induce straddling type-I and staggered type-II band alignments, and the gap values are modified. Moreover, the interlayer coupling and electronic field effects on electronic structures depend on the interface characteristics in Janus MoSSe/GaN heterobilayers. The studies provide the idea to modify the electronic characteristics using interface characteristics in the 2D materials-based vdW heterostructures.