Energy band alignment of GaN/WS 2 van der Waals heterojunction via depth-profile X-ray photoelectron spectroscopy

Abstract Two-dimensional tungsten disulfide (WS 2 ) and three-dimensional gallium nitride (GaN) are both semiconductor materials with excellent physical and chemical properties. Moreover, the GaN/WS 2 heterojunction is considered a potential semiconductor heterostructure for novel solid-state devices. In this report, GaN epitaxial layer is grown via the mechanism of van der Waals (vdW) epitaxy by the technique of plasma-assisted molecular beam epitaxy on the c -sapphire substrate with a few monolayers of WS 2 , prepared by the technique of chemical vapor deposition. During and after the growth, the characterizations of GaN/WS 2 heterostructure are conducted by in situ reflection high-energy electron diffraction, transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy, respectively. This study demonstrates the successful vdW epitaxial growth of GaN/WS 2 heterostructure, which performs type-I energy band alignment with the conduction band offset of 0.26 eV and valence band offset of 1.13 eV. The energy band structure engineering of GaN/WS 2 heterojunction could be applied for the novel solid-state devices.