High-Temp Characterization of Monolayer MoSe₂ FETs for Extreme Environment Sensors & Electronics

Electronic control systems and sensor components are increasingly required to function reliably under extreme temperature conditions. Such high-temperature environments are commonly encountered in aerospace applications—including high-speed bearings, gearboxes, and solar-exposed spacecraft surfaces—as well as in energy generation systems and oil-field operations such as steam-assisted gravity drainage and high-temperature gas wells. However, the availability of transistors and circuits capable of operating above 500 K remains limited. While prior research studies have demonstrated the potential of wide bandgap semiconductors such as SiC and GaN for high-temperature performance, these materials are not yet cost-effective for large-scale deployment. Moreover, several challenges persist, including non-ideal device behaviors such as current collapse, drain lag, and threshold voltage shifts, as well as the need for high-temperature-compatible contacts, passivation techniques, and the development of reliable p-type devices. Consequently, there is a continued demand for alternative material systems suitable for fabricating field-effect transistors (FETs), thin-film transistors (TFTs), and sensors capable of stable operation in high-temperature environments.

This work presents the high-temperature characterization of monolayer MoSe₂ field-effect transistors (FETs), and the role of Pd (palladium) Contacts in facilitating hole transport at a drain voltage of 1 V are analyzed. Compared to the extensively studied monolayer MoS₂, investigations of MoSe₂ remain relatively limited, despite being a promising material among the layered transition-metal dichalcogenides (TMD). Monolayer MoSe₂ exhibits a direct optical bandgap of approximately 1.55 eV and has demonstrated charge carrier mobility values that are, in some cases, higher than those reported for MoS₂. The monolayer MoSe₂ used in this study was synthesized via chemical vapor deposition (CVD) and encapsulated with Al₂O₃ to ensure stability during thermal testing. Transfer characteristics were measured over a temperature range from 298 K to 573 K, using both forward and reverse gate voltage sweeps from 0 V to -60 V. The temperature dependence of the threshold voltage (Vₜₕ) and hysteresis was analyzed. With increasing temperature, the devices exhibited improved current-voltage behavior, a reduction in the magnitude of the threshold voltage (i.e., it became less negative), and increased hysteresis. The use of Pd contacts resulted in ambipolar conduction, with a dominant p-type transport behavior. These findings highlight the potential of monolayer MoSe₂ FETs for use in electronic components and sensors operating at elevated temperatures up to 573 K.