Defect Dynamics in 2D Materials and van der Waals Heterostructures
일 시 : 2022년 10월 26일 수요일 16:30
연 사 : 주 민 규 교수 (숙명여자대학교 응용물리학과)
장 소 : 자연과학관 B117호
HOST : 정 문 석 교수님
초 록
Structural defects in atomically thin two-dimensional (2D) materials considerably modify their intrinsic properties. Thus far, high-resolution transmission electron microscopy and scanning tunneling microscopy with the density functional theory have been conventionally employed to identify microscopic structure and energy states of defects, however, the defect dynamics in 2D materials are little known. In this colloquium, the ionization dynamics of sulfur monovacancy in monolayer MoS2 will be presented via low-frequency (LF) noise nanospectroscopy with conductive atomic force microscopy (C-AFM). Nanoscaled contact area defined by C-AFM tip and relatively low defect density of monolayer MoS2 allow us to probe a few monovacancy defects at a time. In the following section, the origin of random telegraph noise (RTN) of multilayer BP/ReS2 heterojunction diodes in particular at the direct tunneling (DT) conduction regime will be demonstrated. The gate-tunable diode characteristic of BP/ReS2 heterojunction unveils systematically the transition of the charge fluctuation mechanism from drift-diffusion to DT regime. This experimental approach will provide a better opportunity to study the defect dynamics and charge fluctuation mechanism in a wide range of nanomaterials.