Investigation of Thickness-dependent Avalanche Breakdown Phenomena in MoS₂ Field-Effect Transistors

Recently, two-dimensional (2D) molybdenum disulfide (MoS₂) has been widely investigated to realize field-effect transistor (FET) applications.[1] Although their electrical characteristics have been extensively studied, there is no report on the electrical properties of MoS₂ FETs under a high electric field due to their limited efficiency of energy dissipation from atomically-thin thickness.
Here, we report our study of the avalanche breakdown in MoS₂ FETs under high electric fields. The critical electric field (E_CR) and impact ionization rate (α) were carefully investigated. The measured results indicated that the values of E_CR and α had a strong dependence on the layer thickness of MoS₂, which is closely related to its quantum confinement effect in the unique 2D systems. Furthermore, we systemically investigated avalanche breakdown phenomena in MoS₂ FETs with various channel lengths corresponding to electrical fields under different gate bias and temperature conditions. Our study will provide an insight to understand the electrical breakdown and the relationship between the critical factors of avalanche breakdown and the thickness of 2D channel layers.