Abstract
The in-situ observation is of great significance to the study of the growth mechanism and controllability of two-dimensional transition metal dichalcogenides (TMDCs). Here, the differential reflectance spectroscopy (DRS) was performed to monitor the growth of molybdenum disulfide (MoS2) on a SiO2/Si substrate prepared by chemical vapor deposition (CVD). A home-built in-situ DRS setup was applied to monitor the growth of MoS2 in-situ. The formation and evolution of monolayer MoS2 are revealed by differential reflectance (DR) spectra. The morphology, vibration mode, absorption characteristics and thickness of monolayer MoS2 have been confirmed by optical microscopy, Raman spectroscopy, ex-situ DR spectra, and atomic force microscopy (AFM) respectively. The results demonstrated that DRS was a powerful tool for in-situ observations and has great potential for growth mechanism and controllability of TMDCs prepared by CVD. To the best of the authors’ knowledge, it was the first report in which the CVD growth of two-dimensional TMDCs has been investigated in-situ by reflectance spectroscopy.
Highlights
Two-dimensional (2D) materials have attracted enormous attention in optoelectronic devices, flexible sensors, catalysis, and energy conversion due to their outstanding physical and chemical properties [1,2,3,4,5,6,7,8]
The results provide a detailed understanding of the growth evolution for 2D materials and emphasize that differential reflectance spectroscopy (DRS) is a powerful tool for the in-situ characterization of 2D transition metal dichalcogenides (TMDCs) prepared by chemical vapor deposition (CVD)
The MoS2 sample was prepared by atmospheric pressure CVD in a two-zone tube furnace, which was characterized ex-situ by optical microscopy, Raman spectroscopy, DRS and atomic force microscopy (AFM)
Summary
Two-dimensional (2D) materials have attracted enormous attention in optoelectronic devices, flexible sensors, catalysis, and energy conversion due to their outstanding physical and chemical properties [1,2,3,4,5,6,7,8]. 2D transition metal dichalcogenides (TMDCs) have tunable band gaps, which make their application more likely in semiconductor optoelectronic devices than graphene [4]. The preparation of large-area and high-quality 2D thin film materials is the basis for their extensive development and application. The efforts about in-situ observation during growth are conducted to explore the growth mechanism and control the quality of 2D materials. It is quite challenging to investigate the growth process in-situ because the 2D materials normally require high temperature and a wide range of temperature variations
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