Yijin Zhang: Electronic and optical properties of transition-metal dichalcogenides

Group VI-B Transition-metal dichalcogenides (MX2 with M = Mo, W and X = S, Se, Te, abbreviation: TMDs) in the triangular prismatic phase are new class of semiconductors with a high potential for wide kind of applications ranging from the conventional electronics and optics to the next generation technologies such as spintronics and valleytronics. In particular, their unique band structure as well as the valley-constructing properties and phenomena originated from the broken inversion symmetry in the individual layer can be potentially utilized for novel functional applications. We have been investigating the electronic and optical properties of thin flakes of TMDs including valley-constructing phenomena. Our sample is obtained by the mechanical exfoliation from bulk single crystal in order to play with the single domain crystal. The physical properties are also tuned based on the field effect transistors (FET) device configuration with TMDs as the channel materials. We often incorporate a liquid gate dielectric to widen the accessibility to the various properties of TMDs. The liquid gate dielectric additionally facilitates the realization of functional devices based on TMDs.