Effects of temperature and pressure on sulfurization of molybdenum nano-sheets for MoS2 synthesis

The synthesis of high-quality, thickness-controlledmolybdenumdisulfide (MoS2) films via vapor-phase growth remains a challenging process. In thiswork, the synthesis of two-dimensional (2D) MoS2 films via sputtering and sulfurization in a quartz tube furnace was investigated. Thicknesses of MoS2 films were dependent on the thickness of Mo films grown using sputtering. The Raman spectra of the MoS2 films exhibited a 19.12 cm(-1) difference between two peaks, including in-plane vibration (E-2g(1)) and out-of-plane vibration (A(1g)), indicating amonolayer. Roomtemperature photoluminescence measurements indicate a peak spectral emission at 1.89 eV. Surfacemorphology ofmultilayerMoS(2) films and their crystallization processeswere observed using atomic forcemicroscopy and scanning electron microscopy. Low temperature (450 degrees C) synthesis revealed a wide full width at half maximum (FWHM) of both modes, E-2g(1) and A(1g), which indicates poor crystallinity. In contrast, using a high sulfurization temperature (750 degrees C) results in a higher crystallinity or narrow FWHM. Film synthesis at the optimized process conditions (750 degrees C and a pressure of 1 KPa) produced continuous, uniform, and full-coverage films. (C) 2017 Elsevier B.V. All rights reserved.