2D materials and interfaces in high-carrier density regime: a study on optoelectronics and superconductivity

Transition metal dichalcogenides (TMDs) group are the most promising candidate to replace the present semiconductor technology. Their layered nature and the existence of finite electronic band gap in particular compounds such as WS2, WSe2, MoS2, and MoS2 have been a major interest of these 2D materials group. Not to mention, the superconducting (SC) TMDs have been discovered in NbSe2 and TaS2, which give more variety in 2D materials building blocks. Furthermore, with the development of the 2D heterostructure fabrication method, the wide application of 2D materials devices starts to be investigated.

In this thesis, two general ideas are implemented: p- and n-type semiconductor interface, namely p-n junction, and superconducting-normal metal interface. The realization of the ideas is related to the incorporation of electrical double layer transistors (EDLTs) configuration in which the high carrier density regime can be easily accessed. Chapters 2 and 3 discuss the development of lateral 2D p-n junction based on TMDs-BN artificial heterostructure in which the lateral p-n interface is tuned using the combination of EDLT and conventional solid-state gating. Chapter 4 focuses on electrical transport in the superconducting-normal metal junction of field-induced few-layer MoS2 superconductor. Chapter 5 demonstrates the development of a novel technique in 2D heterostructure fabrication technology to achieve high-quality 2D heterostructure devices.