Molybdenum Disulfide Field-Effect Transistor Characterization

The layered semiconductor molybdenum disulfide (MoS₂) has emerged as a leading material for two-dimensional field-effect transistors (FETs) due to its intrinsic band gap, large surface-to-volume ratio and mechanical flexibility. Characterisation typically focuses on key metrics: carrier mobility, threshold voltage (Vₜₕ), subthreshold swing and on/off current ratio. Charge trapping in gate dielectrics and adsorbates at the MoS₂ interfaces introduce hysteresis and bias-temperature instability, while contact resistance at metal–MoS₂ junctions can limit the achievable drive current and complicate extraction of intrinsic transport parameters. Advances in chemical vapour deposition, high-κ dielectric integration and encapsulation have improved device uniformity and stability. Comprehensive studies of defect formation under electrical stress, environmental effects on transport and heterostructure engineering are deepening our understanding of the complex interactions between synthesis, device architecture and electrical performance, and are guiding the development of low-power logic, sensing and optoelectronic applications based on MoS₂ FETs.

Research from Nature Portfolio

Recent investigations have shown that prolonged operation under high electric fields induces a range of defects in monolayer MoS₂ grown by chemical vapour deposition. Electrically induced piezoelectric distortions lead to threshold-voltage instabilities, modified channel conductance and a pronounced metal–insulator transition. These defects enhance screening of charged impurities and improve channel-dielectric coupling, resulting in better thermal dissipation but also in a shift of supply-voltage requirements for low-power circuits.

Studies of CVD-grown monolayer MoS₂ FETs under varying ambient conditions have demonstrated that physisorbed water and oxygen molecules act as charge-trapping centres, causing non-monotonic threshold-voltage shifts and degraded mobility. Pumping to high vacuum or annealing in situ reduces hysteresis by desorbing interface species, while cooling suppresses trap dynamics. Quantification of trap densities on the order of 10¹² cm⁻² eV⁻¹ has guided strategies for surface passivation and improved device reliability.

Molybdenum Disulfide Field-Effect Transistor Characterization publication trend

The graph below shows the total number of articles in molybdenum disulfide field-effect transistor characterization across all publications each year (not limited to Nature Index journals).

Technical terms

Field-effect transistor (FET): A device in which a gate voltage modulates the conductance of a semiconductor channel, controlling current between source and drain terminals.

Charge trapping: Capture of carriers by defect states in dielectrics or at interfaces, leading to shifts in threshold voltage and hysteresis in transfer characteristics.

Hysteresis: A phenomenon whereby the current–voltage characteristics depend on the history of the applied gate voltage sweep, often due to slow trap dynamics.

Threshold voltage (Vₜₕ): The gate voltage at which a significant conducting channel forms, marking the transition between off and on states in a FET.

Schottky barrier: A potential energy barrier for carriers formed at a metal–semiconductor junction, influencing contact resistance and injection efficiency.

Carrier mobility: A measure of how quickly charge carriers move through a semiconductor in response to an electric field, typically expressed in cm² V⁻¹ s⁻¹.

Van der Waals heterojunction: An interface between two different two-dimensional materials bonded by van der Waals forces, enabling novel electronic and optoelectronic properties.

References

1. Origin of electrically induced defects in monolayer MoS2 grown by chemical vapor deposition. Communications Materials (2023).
2. Ambient effects on electrical characteristics of CVD-grown monolayer MoS2 field-effect transistors. Scientific Reports (2017).
3. Dominant n-type conduction and fast photoresponse in BP/MoS2 heterostructures. Surfaces and Interfaces (2024).
4. Impact of contact resistance on the electrical properties of MoS2 transistors at practical operating temperatures. Beilstein Journal of Nanotechnology (2017).