Shanxi University

Abstract:

Finding methods or material systems to achieve high-mobility two-dimensional semiconductors is an important research direction in condensed matter physics and even nanoelectronics.

It is well known that since the discovery of the quantum Hall effect in high-mobility two-dimensional electron gases in quantum wells over 40 years ago, the realization of the quantum Hall effect or fractional quantum Hall effect in two-dimensional electron systems remains very limited. Among them, the low-temperature ground state of high-mobility two-dimensional semiconductors is particularly difficult to realize, mainly due to the extremely challenging acquisition of Ohmic contacts.

In this talk, we will introduce the latest progress in the stable and reliable preparation of low-temperature Ohmic contacts in N-type molybdenum disulfide field-effect transistors, where the quantum limit (filling factor of niu=1) can be achieved, and fractional quantum Hall effect (FQHE) with fillings of 2/5 and 4/5 under mK temperatures are observed [1]. This is the first two-dimensional n-type semiconductor material where the FQHE can be observed through electrical transport (excluding those topological flat band systems). Our results of ultra-high mobility N-type MoS₂ layers can play as a platform for future low temperature quantum electronic devices.

Biography:

Zheng Han’s studies mainly focus on the emerging physical properties of functional materials in mesoscopic sizes, and on further implementing these interesting properties in future applications of nano-assemblies and nanoelectronics. In the past few years, he has revealed a series of exotic physical properties of such systems, with the related works published in journals including Nature, Nature Nanotechnology, Nature Communications.

邀请人：刘恩克（82649085，ekliu@iphy.ac.cn）