Chemical Vapor Deposition of Molybdenum Disulfide Thin Films
Date Issued
2016
Date
2016
Author(s)
Chan, Yu-Hao
Abstract
Molybdenum disulfide (MoS2) is a two-dimensional hexagonal lattice. In contrast to graphene, which has no bandgap by nature, MoS2 monolayer has a direct bandgap of 1.8 eV due to the quantum confinement effect. It exhibits a high on/off current ratio and strong luminescence. Therefore, MoS2 monolayers have attracted much attention in experimental and theoretical researches for its potential applications in optoelectronic devices, field effect transistors, low power switches, valleytronics, etc. For practical applications, it is of importance to develop a reliable growth process to synthesize large-area, uniform, and continuous MoS2 monolayers. Here we use the chemical vapor deposition method for the growth of MoS2 atomic layers, using the precursors, MoO3 and sulfur and high-purity argon carrier gas, onto the silicon oxide substrates. In this study, we investigate the influences of growth temperature, pressure, substrate positions and the substrate orientation on the morphology and thickness of the MoS¬2 thin films and infer the mechanism of MoS2 growth in our system from the experimental results. Continuous MoS2 bilayers in a size of 3.5×2.2 cm2 can be obtained. They exhibit an on/off ratio of 104, mobility of ~10 cm2/V-s, and high luminescence, which is ~13 times stronger than that of the exfoliated MoS2 monolayers.
Subjects
molybdenum disulfide
chemical vapor deposition
auger electron spectroscopy
transmission electron microscopy
raman spectroscopy
photoluminescence
Type
thesis
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