Vertically stacked GaN/WX (X = S, Se, Te) heterostructures for photocatalysts and photoelectronic devices.

Tremendous attention has been paid to vertically stacked heterostructures owing to their tunable electronic structures and outstanding optical properties. In this work, we explore the structural, electronic and optical properties of vertically stacked GaN/WX (X = S, Se, Te) heterostructures using density functional theory. We find that these stacking heterostructures are all semiconductors with direct band gaps of 1.473 eV (GaN/WTe), 2.102 eV (GaN/WSe) and 1.993 eV (GaN/WS). Interestingly, the GaN/WS heterostructure exhibits a type-II band alignment, while the other two stackings of GaN/WSe and GaN/WTe heterostructures have type-I band alignment. The optical absorption of GaN/WX heterostructures is very efficient in the visible light spectrum. Our results suggest that GaN/WX heterostructures are promising candidates for photocatalytic water splitting and photoelectronic devices in visible light.