Mesoscopic Transport in Novel Graphene Quantum Devices

Abstract

Two-dimensional (2D) materials are a class of extraordinarily thin materials that are normally referred to being one or two atoms thick. Compared to their bulk counterparts, they would exhibit distinct unique physical properties due to the constrains of the size in one dimension. The remarkable advantages could be offered by 2D materials, such as the electrical, mechanical, and thermal properties, intriguing intense scientific research and great interests from various fields. Being the most well-studied 2D material of them all, graphene becomes a shining star in the family, providing a promising platform of quantum phenomena studies in a 2D regime. The later exploration of transition metal dichalcogenides (TMDs) also provides scientists new insight of the 2D devices applications in terms of the electronics and optoelectronics. Undoubtedly, the research of the novel 2D materials uncovers unprecedented advantages and provides one of the essential building blocks for next generation devices. This thesis centers itself among various exotic physics quantum phenomena and demonstrates several different approaches in terms of the quantum phenomena investigation in 2D material devices. One of the approaches is to change the materials band structure through twist and stacking. The moiré potential and the proximity effect between the layers in van der Waals structures could change the fillings of the states, leading to the emergence of strong correlation, generate charge transfer, therefore resulting into the change of the properties and observations of novel quantum phenomena. The second approach is to utilize the gate-defined structures to locally tune material band structure by changing the electrical potential or applying the displacement field. Due to the fine structure of the designed gate configurations, electronic states can be controlled within a nano-scale regime. The provided flexibility of the gate structures gives the possibility of creating, controlling, or modifying quantum phenomena, as well as achievement of the relevant applications.