Dynamic Probing of Neutron-Induced Reliability Degradation in MoS₂ and WS₂ Transistors

Two-dimensional transition-metal dichalcogenide (TMD) field-effect transistors (FETs) are promising candidates for electronics operating in harsh environments, yet their tolerance to neutron irradiation remains largely unexplored. Here, we investigate the electrical degradation behavior of MoS₂ and WS₂ FETs under 2.2 MeV neutron irradiation and identify the dominant mechanisms governing the performance loss. After neutron irradiation, both devices exhibit pronounced electrical degradation, which is attributed to three coupled effects: (i) generation within the TMD channel that increases channel resistance, (ii) accumulation of interface- and oxide-trapped charges that perturbs electrostatic control, and (iii) deterioration of the metal-semiconductor Schottky contacts. Notably, the WS₂ FETs show discernible degradation even at relatively low neutron fluence, revealing a substantially higher neutron susceptibility than MoS₂. This difference is attributed to the distinct neutron-matter interaction characteristics of the constituent elements, which lead to a greater extent of energy transfer and defect formation under irradiation. Furthermore, through in situ electrical measurements performed during neutron irradiation, we directly analyze the evolution of device characteristics under operation conditions and assess device stability in extreme radiation environments. Our results establish a mechanistic framework for neutron-induced degradation in 2D TMD transistors and provide design guidelines for radiation-resilient, atomically thin electronics.