Investigation on the effect of chemical mechanical polishing sapphire substrate on chemical vapor deposition growth of two-dimensional MoS2

Abstract

Two-dimensional molybdenum disulfide (2D MoS2), with atomic-level thickness, whose crystal crystallinity and size are easily influenced by the surface morphology of the substrate during growth. This work systematically investigates the impact of chemical mechanical polishing (CMP) sapphire substrate on chemical vapor deposition (CVD) growth of 2D MoS2. A green and highly efficient CMP method for the sapphire substrate is first proposed, whose maximum material removal rate (MRR) of 4.27 µm/h with surface roughness (Ra) of 0.10 nm (AFM, scanning area of 5 × 5 μm2) can be attained. The size and thickness statistics of 2D MoS2 domains grown on different substrates indicate that the CMP sapphire substrate in this work can promote the size and monolayer uniformity of 2D MoS2 during CVD growth. Meanwhile, Raman and photoluminescence (PL) spectra of monolayer MoS2 grown on different substrates also indicates the monolayer MoS2 grown on the CMP sapphire substrate in this work has superior crystalline quality and optical properties. The above findings have provided new insights into the mechanisms underlying 2D MoS2 growth on surfaces in various states and are expected to accelerate the development of large size large-size and high-quality growth of two-dimensional material for further device applications.