One-step H ₂ S reactive sputtering for 2D MoS ₂ /Si heterojunction photodetector

Abstract

A technique for directly growing two-dimensional (2D) materials onto conventional semiconductor substrates, enabling high-throughput and large-area capability, is required to realise competitive 2D transition metal dichalcogenide devices. A reactive sputtering method based on H₂S gas molecules and sequential in situ post-annealing treatment in the same chamber was proposed to compensate for the relatively deficient sulfur atoms in the sputtering of MoS₂ and then applied to a 2D MoS₂/p-Si heterojunction photodevice. X-ray photoelectron, Raman, and UV-visible spectroscopy analysis of the as-deposited Ar/H₂S MoS₂ film were performed, indicating that the stoichiometry and quality of the as-deposited MoS₂ can be further improved compared with the Ar-only MoS₂ sputtering method. For example, Ar/H₂S MoS₂ photodiode has lower defect densities than that of Ar MoS₂. We also determined that the factors affecting photodetector performance can be optimised in the 8-12 nm deposited thickness range.