Layer Controlled Growth of MoS2 thin film through MOCVD

Abstract

Two-dimensional materials, especially TMDs, have attracted a lot of attention for their superior electrical and optical properties in the fields of electronics, optics, and optoelectronics. Unlike bulk materials, TMDs makes up the layer stacked structure by van der Waals (vdW) force.[1] Due to this unusual layer stacked structure, TMDs shows the layer dependent electrical and optical properties. Although TMDs shows the unique properties in accordance with the number of layers, it still remains to control the number of layers of TMDs through growth process. In this study, we report the layer controlled growth of TMDs (especially MoS2) through metal-organic chemical vapour deposition (MOCVD). [2] With careful adjustment of precursor ratio, partial pressure, and growth time, we successfully synthesized MoS2 thin film ranging from 1 layer to 5 layers. In order to confirm the successful layer control of MoS2, we analyzed MOCVD-grown MoS2 thin films using a variety of tools such as photoluminescence (PL), Raman spectroscopy, differential reflectance spectroscopy (DRS), and field effect transistors (FETs). Combining the results from DRS and PL, we also confirmed the evolution of electronic structure in band diagram as increasing the number of layers. Finally, we also investigated the electrical performance as a function of the number of layers of MoS2 channel in terms of resistance, threshold voltage, and mobility.