Electron beam-induced reduction of Schottky barrier width for low contact resistance molybdenum disulfide field-effect transistor

Abstract

In order to address the issue of the substantial contact resistance commonly encountered at the metal and two-dimensional (2D) semiconductors, an approach involving the reduction of Schottky barrier width by electron beam-induced defects has been demonstrated. Molybdenum disulfide (MoS2) field-effect transistors (FETs) demonstrate notable enhancements in their performance after electron beam irradiation (EBI) of the contact regions. Systematic studies revealed an optimal relationship between EBI dose and MoS2 layer thickness, with field-effect mobility (μEF) as a key metric. Under an accelerating voltage of 20 kV and an irradiation dose of 600 µC/cm2, 7 nm thick MoS2 FETs achieved a μFE exceeding 150 cm2/V s, representing a tenfold improvement over untreated devices, while contact resistance decreased significantly to 1.4 kΩ µm, an order of magnitude reduction. The observed performance improvement is attributed to EBI-induced sulfur vacancies, which narrow the Schottky barrier width by approximately 45% and enhance electron injection efficiency. The results highlight that EBI-induced defect engineering is a promising method for optimizing electrical performance in 2D-based FETs.