Statistically Resolving Thickness-Dependent Electrical Characteristics in Multilayer-MoS2 Transistors

Abstract

Atomically thin 2D semiconductors enable excellent electrostatic control even in highly scaled transistors with few-nanometer gate lengths. The electrical characteristics of 2D transistors can vary significantly with the number of layers, yet how device behavior evolves with channel thickness remains statistically unexplored. This limitation mainly arises from the difficulty of obtaining large numbers of single-crystal flakes with well-controlled thickness and fabricating devices. Here, we demonstrate the thickness-dependent electrical characteristics of single-flake MoS2 transistors correlating optical observables with the monolayer (ML) numbers. The optical intensity serves as an indicator of flake thickness for identifying the number of MLs, while algorithm-based filtering of blurry edges and non-uniform intensities enables the selection of high-quality flakes. The filtered flakes are subsequently grouped into distinct thickness clusters based on their optical intensity distributions. The resulting thickness clusters are validated by atomic force microscopy, yielding flakes spanning 3-8 MLs. Automated device layout generation allows the electrical characterization of 1615 transistors selected from over 120000 flakes, providing insight into thickness-dependent charge carrier injection and transport behavior. Our findings offer a statistically grounded framework linking flake thickness to electrical characteristics and demonstrate the utility of readily accessible optical microscopy for accelerating 2D semiconductor device research.