How Do Quantum Effects Influence the Capacitance and Carrier Density of Monolayer MoS<sub>2</sub> Transistors?
basic_science · Level V
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- Record sourced from PubMed, PMID 36786518.
- Also identified by DOI 10.1021/acs.nanolett.2c03913.
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Abstract
When transistor gate insulators have nanometer-scale equivalent oxide thickness (EOT), the gate capacitance (<i>C</i><sub>G</sub>) becomes smaller than the oxide capacitance (<i>C</i><sub>ox</sub>) due to the quantum capacitance and charge centroid capacitance of the channel. Here, we study the capacitance of monolayer MoS<sub>2</sub> as a prototypical two-dimensional (2D) channel while considering spatial variations in the potential, charge density, and density of states. At 0.5 nm EOT, the monolayer MoS<sub>2</sub> capacitance is smaller than its quantum capacitance, limiting the single-gated <i>C</i><sub>G</sub> of an <i>n</i>-type channel to between 63% and 78% of <i>C</i><sub>ox</sub>, for gate overdrive voltages between 0.5 and 1 V. Despite these limitations, for dual-gated devices, the on-state <i>C</i><sub>G</sub> of monolayer MoS<sub>2</sub> is 50% greater than that of silicon at 0.5 nm EOT and more than three times that of InGaAs at 1 nm EOT, indicating that such 2D semiconductors are promising for improved gate control of nanoscale transistors at future technology nodes.