Fabrication, Characterization, and Modeling of Monolayer Molybdenum Disulfide Radio Frequency Transistors

Radio frequency (RF) transistors using US Army Combat Capabilities Development Command Army Research Laboratory grown monolayer molybdenum disulfide (MoS2) were fabricated and tested in the ground-signal-ground configuration. Devices were fabricated and characterized on both hard (silicon dioxide) and flexible (polyimide) substrates. Devices operated with de-embedded fT and fmax over 3 GHz on rigid substrates and 1 GHz on flexible substrates. Standard metal-oxide-semiconductor field-effect transistor current-voltage equations are applied to experimental results of a DEVCOM Army Research Laboratory fabricated RF transistors that use monolayer MoS2 as the channel material. A method to accurately extract the key device parameters of threshold voltage, contact resistance, and transconductance is introduced and discussed. The experimental transistor curves deviate from the transistor models in regions of operation with both a high gate and drain bias. According to related literature, significant device self-heating occurs at these operation regimes causing significant velocity saturation/mobility degradation.