Abstract
In this letter, a compact model for charge and drain current in molybdenum disulfide (MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) field-effect transistors (FETs) is developed, which is valid from ballistic to quasi-ballistic to drift-diffusion electronic transport regimes. Considering the influence of trap charges in MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> transistors, a physical-based and analytical charge model is derived. Based on the virtual source model which applies to both ballistic and quasi-ballistic transports, the carrier number density and current expressions are combined to yield the current-voltage (I-V) characteristics. Furthermore, the presented model is validated by experimental data as well as recently reported simulations for MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> FETs with different gate lengths. It shows that our model is accurate, straight-forward, scalable and compatible for short- and long-channel devices.
Highlights
Recently, considerable attention has been paid to 2-D layered transition metal dichalcogenide (TMD), for example, the single-atomic-layer molybdenum disulfide (MoS2) because of its excellent intrinsic carrier transport properties [1] and transistor scalability [2]
To project the ultimate scaling limit of monolayer MoS2 transistors, ballistic quantum transport simulations solving by nonequilibrium Green’s function (NEGF) were performed [1]
The previous researches show that ballistic transport needs to be modeled for MoS2 transistor if its channel length (L) is smaller than the mean free path (λ), i.e., L < λ
Summary
Considerable attention has been paid to 2-D layered transition metal dichalcogenide (TMD), for example, the single-atomic-layer molybdenum disulfide (MoS2) because of its excellent intrinsic carrier transport properties [1] and transistor scalability [2]. To perform the ballistic transport effect, some compact models for short-channel devices [10], [11] were proposed but only for the subthreshold region. The charge expression in this model was given by a conventional device equation Qtop = COX(Vgs − VT ) where VT is the threshold voltage, and used a smoothing function to connect different regions. ZENG et al.: COMPACT MODEL OF MoS2 FETs FROM DRIFT-DIFFUSION TO BALLISTIC CARRIER TRANSPORT REGIMES TABLE 1. The calculated drain current is compared with available simulations and measurements at different channel lengths (1.5 μm, 50 nm and 1 nm) to ensure the model’s accuracy and scalability
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