Observation of Rich Defect Dynamics in Monolayer MoS2

Defects play a pivotal role in limiting the performanceand reliabilityof nanoscale devices. Field-effect transistors (FETs) based on atomicallythin two-dimensional (2D) semiconductors such as monolayer MoS2 are no exception. Probing defect dynamics in 2D FETs is thereforeof significant interest. Here, we present a comprehensive insightinto various defect dynamics observed in monolayer MoS2 FETs at varying gate biases and temperatures. The measured source-to-draincurrents exhibit random telegraph signals (RTS) owing to the transferof charges between the semiconducting channel and individual defects.Based on the modeled temperature and gate bias dependence, oxygenvacancies or aluminum interstitials are probable defect candidates.Several types of RTSs are observed including anomalous RTS and giantRTS indicating local current crowding effects and rich defect dynamicsin monolayer MoS2 FETs. This study explores defect dynamicsin large area-grown monolayer MoS2 with ALD-grown Al2O3 as the gate dielectric.