Quantum Materials - 05

Abstract

Carrier density is a crucial metric for semiconductor performance, often influencing device performance, reflecting the material‘s controllability and determining band filling and Fermi level, thereby influencing the material’s optical and electrical behavior. Two-dimensional materials are only one or a few atomic layers thick, so an external electric field can directly penetrate the entire material. The electric field has a significant impact on the distribution of electrons inside the material. Compared with three-dimensional materials, two-dimensional materials are more sensitive to changes in external electric fields. Therefore, applying an electric field to two-dimensional materials is an effective way to study carrier. Among many two-dimensional materials, TMDs (Transition Metal Dichalcogenides), with their two-dimensional structure and tunable properties, provide a unique platform for precisely controlling carrier behavior, making them key materials for next-generation electronic and optoelectronic devices. By using our laboratory’s advanced two-dimensional material MOCVD growth system, we have fabricated a single-layer two-dimensional heterostructure that WS₂ with a nanoscale MoS₂ channel embedded within it[1], Fig.1. Due to its two-dimensional structure, monolayer TMDs are highly sensitive to applied electric fields, enabling precise control of carrier density. Furthermore, the varying band gaps of different TMDs result in distinct properties, particularly their varying response curves under the same electric field. This point allows, under certain situations, the carrier distribution in TMDs to be shifted from two-dimensional to one-dimensional distribution. Therefore, in this study, using contact AFM as a tool, we will investigate the process of this controlled transition from a two-dimensional to one-dimensional carrier distribution in monolayer two-dimensional materials, Fig.2, this will reveal the unique properties of carriers in the two-dimensional/one-dimensional distribution switchable system, further deepen our understanding of the quantum world, and provide a theoretical basis for the preparation of quantum devices.