Role of GaN surface Termination on Structural and Electronic Properties of 2D/GaN and Metal/2D/GaN Heterostructures

Two-dimensional (2D) van-der-Waals (vdW) materials such as graphene and TMDCs have shown great promise in the field of nanoelectronics optoelectronic properties. In order to realize their full potential as channel materials in devices, these materials should form high-quality interfaces with bulk 3D substrates and metal contacts to minimize contact resistance and maximize current. Recently, we demonstrated the successful growth of a single layer (SL) of molybdenum disulfide (MoS₂) on a GaN substrate through vdW epitaxy for vertical transistor [1]. Device characterization also revealed that the GaN-surface quality and polarity influenced both the structural and electronic properties of the 2D/3D heterostructures, mainly due to modulating vdW forces between the 2D layer and 3D substrate [2]. Motivated by these observations, here we present a first-principles study of structural and electronic properties of MoS₂/GaN and metal/ MoS₂/GaN heterostructures with Ga- and N-terminated GaN surfaces. We compare and contrast their material and electronic properties such as stacking order, vdW gap, work function, and Schottky barrier height (SBH). [1] Ruzmetov, D and et al., ACS Nano 2016, 10, 3580–3588. [2] O’Regan, T. P. Ruzmetov, D.; Neupane, M. R., and et al., APL. 2017, 111, 051602.