Wang Wenzhao,Chen Xiaoxiao,Zeng Xiangbin,Wu Shaoxiong,Zeng Yang,Hu Yishuo,Xu Sue,Zhou Guangtong,Cui Hongxing
Recently, great efforts have been devoted to study of molybdenum disulfide (MoS 2 ), particularly monolayer MoS 2 semiconductor thin films, due to its excellent electrical and optical properties. Direct growth of continuous monolayer MoS 2 films by ambient-pressure chemical vapor deposition is reported herein. Optical microscopy, Raman spectroscopy, photoluminescence spectra (PL), atomic force microscopy, x-ray photoelectron spectroscopy (XPS), and high-resolution transmission electronic microscopy were used to characterize the electronic and structural properties of the films, demonstrating that the MoS 2 films grown on silicon dioxide/silicon (SiO 2 /Si) substrate with spatial size on micron scale were high quality, single crystal, continuous, and monolayer. Raman and PL mapping were performed to confirm the uniformity of the monolayer MoS 2 films. The morphological variation of the MoS 2 films after different reaction times was observed by optical microscopy and scanning electron microscopy, revealing the growth process and thus helping to understand that the growth mechanism during synthesis of continuous large-area films depends on the distribution of the reactive intermediate molybdenum oxide (MoO 3− x ) due to its lower saturation vapor density. Back-gated transistors based on MoS 2 films were fabricated, exhibiting current on/off ratio of ∼ 10 4 and subthreshold swing (SS) of 0.44 V dec −1 . This work contributes to synthesis of large-area continuous films, thus paving the way for future scaled-up fabrication of MoS 2 electronic devices.
Herein, novel stabilized aluminum titanate whiskers were prepared via the molten salt method using alumina as the aluminum source, titania as the titanium source, magnesium carbonate as the stabilizer, and sodium molybdate as the molten salt. The influence of the amount of molten salt on the one-dimensional selectivity of the stabilized aluminum titanate whiskers was examined using XRD, SEM, TEM and other established testing methods, and the growth mechanism of aluminum titanate whiskers was discussed. The results confirmed that an excessive or insufficient amount of molten salt sodium molybdate is not conducive to the preparation of stabilized aluminum titanate whiskers. The optimum molten salt amount to be added is a molar ratio of 20% to aluminum titanate. A high yield of stabilized aluminum titanate whiskers, with diameters ranging from 20–60 μm and an aspect ratio >10 can be prepared by holding the sample at 1300°C for 6 h. The growth direction of the stabilized aluminum titanate whiskers is the [100] direction.
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