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Direct synthesis of MoS2 nanodots by chemical vapor deposition

This result is elucidated through the quantum confinement effect. The PL emission shows a pronounced peak at 505 nm that is significant blue shift compared to thin layer MoS2. The interpretation of this phenomena is also discussed in detail. | Communications in Physics, Vol. 28, No. 4 (2018), pp. 379-386 DOI:10.15625/0868-3166/28/4/12650 DIRECT SYNTHESIS OF MoS2 NANODOTS BY CHEMICAL VAPOR DEPOSITION VY ANH VUONG AND CHU MANH HUNG † International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology, No. 1 Dai Co Viet, Hanoi, Vietnam † E-mail: mhchu@itims.edu.vn/ hung.chumanh@hust.edu.vn Received 08 June 2018 Accepted for publication 30 October 2018 Published 15 December 2018 Abstract. The current work reports a direct synthesis of MoS2 nanodots by a chemical vapor deposition method. The morphological, crystal structure, and optical properties of the growing MoS2 are investigated by field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), X-ray diffraction (XRD), Raman and Photoluminescence (PL) spectroscopy, respectively. High magnification FESEM image reveals a layer of MoS2 nanodots with the average size of about 10 nm. AFM and XRD data indicate the surface roughness of the nanodot array of about 1.7 nm and the formation of 3R-MoS2 structure, respectively. Resonance Raman data exhibits the two active E12g and A1g modes corresponding to in-plane vibration of Mo and S atoms centered at 383.3 cm−1 and to out of plane vibration of S atoms located at 407.1 cm−1 , respectively. The spacing between two peaks is about 23.8 cm−1 , which can be used to evaluate the number of MoS2 layer. The Raman spectrum also indicates any intensity enhancement of the A1g peak compared to the E12g peak. This result is elucidated through the quantum confinement effect. The PL emission shows a pronounced peak at 505 nm that is significant blue shift compared to thin layer MoS2 . The interpretation of this phenomena is also discussed in detail. Keywords: MoS2 ,thin layer, nanodots, CVD. Classification numbers: 81.15.Gh; 62.23.Eg; 81.15.-z. c 2018 Vietnam Academy of Science and Technology 380 DIRECT SYNTHESIS OF MoS2 NANODOTS BY CHEMICAL VAPOR DEPOSITION I.