Paper 2D-TuP11
Growth and Electrical, Nano-Optical Characterization of semiconducting MoS₂/WS₂ in-plane Heterostructures

Tuesday, October 22, 2019, 6:30 pm, Room Union Station B

In-plane heterojunctions of atomic-thick (2D) semiconductors (MoS₂/WS₂) are novel structures that can potentially pave the way for efficient ultrathin and flexible optoelectronics, such as light sources and photovoltaics. Such heterostructures (HS) are very rare and not much is known about their characteristics. They can only be achieved through a synthetic growth process such as chemical vapor deposition (CVD). This is unlike vertical heterostructures, for which the materials can be mechanically stacked one layer on top of the other. The CVD growth of in-plane heterostructure is a thermodynamically driven process and presents a number of challenges to control the vapor pressure of the precursors. Additionally, new analytical tools need to be developed in order to gain access to and understand the physical properties of these HS.

Here, we report a one-step CVD growth of monolayer (1 nm) thick MoS₂/WS₂ in-plane heterostructures. We have characterized their morphological and optical properties using micro-Raman and photoluminescence spectroscopy. Kelvin probe force microscope was used to extract the surface potential profile across the MoS₂/WS₂ heterojunction boundary, which was then used to gain access to fundamental semiconductor heterostructure parameters such as depletion layer width and built-in field across the MoS₂-WS₂ interface. In-addition more rigorous study of heterostructures interface by tip enhanced PL (TEPL) had been performed.