Channel Thickness-Dependent Degradation of Field-Effect Mobility in Multilayer MoS2 Transistors

Two-dimensional (2D) semiconductors such as molybdenum disulfide (MoS2) may serve as state-of-the-art logic devices as we progress toward the 2 nm technology node. Here, we show that mobility degradation is influenced by the channel thickness of multilayer MoS2 transistors. Thicker MoS2 channels exhibited less degradation of field-effect mobility caused by the transverse electric field (E-field), given the considerable bulk conduction current. Kelvin probe force microscopy (KPFM) was used to measure the channel thickness-dependent contact potential difference gradient. Numerical simulation confirmed that the vertical E-field was well screened by the bulk conduction channel. The results enhance our understanding of multilayer MoS2 transistor operation and will enable performance optimization.