Vacuum ultraviolet radiation effects on two-dimensional MoS₂ field-effect transistors

Atomically thin MoS₂ has generated intense interest for emerging electronics applications. Its two-dimensional nature and potential for low-power electronics are particularly appealing for space-bound electronics, motivating the need for a fundamental understanding of MoS₂ electronic device response to the space radiation environment. In this letter, we quantify the response of MoS₂ field-effect transistors (FETs) to vacuum ultraviolet (VUV) total ionizing dose radiation. Single-layer (SL) and multilayer (ML) MoS₂ FETs are compared to identify differences that arise from thickness and band structure variations. The measured evolution of the FET transport properties is leveraged to identify the nature of VUV-induced trapped charge, isolating the effects of the interface and bulk oxide dielectric. In both the SL and ML cases, oxide trapped holes compete with interface trapped electrons, exhibiting an overall shift toward negative gate bias. Raman spectroscopy shows no variation in the MoS₂ signatures as a result of VUV exposure, eliminating significant crystalline damage or oxidation as possible radiation degradation mechanisms. Overall, this work presents avenues for achieving radiation-hard MoS₂ devices through dielectric engineering that reduces oxide and interface trapped charge.