文摘
Large-area and highly crystalline monolayer molybdenum disulfide (MoS<sub>2sub>) with a tunable grain size was synthesized in a H<sub>2sub> atmosphere. The influence of introduced H<sub>2sub> on MoS<sub>2sub> growth and grain size, as well as the corresponding mechanism, was tentatively explored by controlling the H<sub>2sub> flow rate. The as-grown monolayer MoS<sub>2sub> displays excellent uniformity and high crystallinity evidenced by Raman and high-resolution transmission electron microscopy. The Raman results also give an indication that the quality of the monolayer MoS<sub>2sub> synthesized in a H<sub>2sub> atmosphere is comparable to that synthesized by using seed or mechanical exfoliation. In addition, the electronic properties and dielectric inhomogeneity of MoS<sub>2sub> monolayers were also detected in situ via scanning microwave microscopy, with measurements on impedance and differential capacitance (dC/dV). Back-gated field-effect transistors based on highly crystalline monolayer MoS<sub>2sub> shows a field-effect mobility of 鈭?3.07 cm<sup>2sup> V<sup>鈥?sup> s<sup>鈥?sup> and an I<sub>onsub>/I<sub>offsub> ratio of 鈭?.1 脳 10<sup>7sup>, indicating that the synthesis of large-area and high-quality monolayer MoS<sub>2sub> with H<sub>2sub> is a viable method for electronic and optoelectronic applications.