Department of Physics and the William Mong Institute of Nano Science and Technology, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
Department of Condensed Matter Physics, Group of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, CH1211 Geneva, Switzerland.
Nat Commun. 2015 Jan 14;6:6088. doi: 10.1038/ncomms7088.
The metal-insulator transition is one of the remarkable electrical properties of atomically thin molybdenum disulphide. Although the theory of electron-electron interactions has been used in modelling the metal-insulator transition in molybdenum disulphide, the underlying mechanism and detailed transition process still remain largely unexplored. Here we demonstrate that the vertical metal-insulator-semiconductor heterostructures built from atomically thin molybdenum disulphide are ideal capacitor structures for probing the electron states. The vertical configuration offers the added advantage of eliminating the influence of large impedance at the band tails and allows the observation of fully excited electron states near the surface of molybdenum disulphide over a wide excitation frequency and temperature range. By combining capacitance and transport measurements, we have observed a percolation-type metal-insulator transition, driven by density inhomogeneities of electron states, in monolayer and multilayer molybdenum disulphide. In addition, the valence band of thin molybdenum disulphide layers and their intrinsic properties are accessed.
金属-绝缘体转变是原子层状二硫化钼的显著电特性之一。尽管电子-电子相互作用的理论已被用于模拟二硫化钼中的金属-绝缘体转变，但转变的潜在机制和详细过程仍在很大程度上未被探索。在这里，我们证明了由原子层状二硫化钼构建的垂直金属-绝缘体-半导体异质结构是探测电子态的理想电容结构。垂直配置的优势在于消除了在能带尾部的大阻抗的影响，并允许在宽的激发频率和温度范围内观察到在二硫化钼表面附近完全激发的电子态。通过结合电容和输运测量，我们已经观察到了由电子态密度不均匀性驱动的，在单层和多层二硫化钼中发生的渗流型金属-绝缘体转变。此外，还可以探测到薄的二硫化钼层的价带和它们的固有特性。
