Abstract
Tungsten disulfide (WS2) monolayer is a direct band gap semiconductor. The growth of WS2 monolayer hinders the progress of its investigation. In this paper, we prepared the WS2 monolayer through chemical vapor transport deposition. This method makes it easier for the growth of WS2 monolayer through the heterogeneous nucleation-and-growth process. The crystal defects introduced by the heterogeneous nucleation could promote the photoluminescence (PL) emission. We observed the strong photoluminescence emission in the WS2 monolayer, as well as thermal quenching, and the PL energy redshift as the temperature increases. We attribute the thermal quenching to the energy or charge transfer of the excitons. The redshift is related to the dipole moment of WS2.
Highlights
Tungsten disulfide (WS2 ) monolayer, a direct band gap semiconductor, shows strong photoluminescence (PL) emission [1,2]
Yun et al [3] found the non-uniformity of the PL emission in WS2 monolayer
Kim et al [4] suspected that the PL emission originated from the exciton complexes
Summary
Tungsten disulfide (WS2 ) monolayer, a direct band gap semiconductor, shows strong photoluminescence (PL) emission [1,2]. Reported the growth of WS2 monolayer on the SiO2 /Si substrate through sulfurization of tungsten oxide powders. Gao et al [16] reported the growth of WS2 monolayer with millimeter scale using catalyst They found the photoluminescence (PL) emission intensity at 612.6 nm was 103 times stronger than bulk material. Molybdenum disulfide reacted with the transport agent water vapor to form molybdenum oxide at high temperature. The molybdenum oxide reacted with sulfur and transformed into a molybdenum disulfide monolayer at a low temperature. In this method, water vapor was used as the transport agent and the nucleation promoter. The introduction of water vapor promoted the molybdenum disulfide monolayer growth. The PL change couldalso be used as a detector of temperature change
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