A MOS capacitor model for ultra-thin 2D semiconductors: the impact of interface defects and channel resistance
Abhinav Gaur, Tarun Agarwal, Inge Asselberghs, Iuliana Radu, Marc Heyns, Dennis Lin
Abstract
Abstract In an edge capacitor based on 2D semiconductors, charge transport in the channel leads to frequency dispersion in capacitance and peaks in conductance, which convolutes information from interface defects ( D it ). If not careful, D it can be grossly misinterpreted. In this study we develop a distributed MOS capacitor model that distinguishes between these two effects. We incorporate charge transport in terms of channel resistance and evaluate the impact of interface defects in few monolayers thick (1 − 5 layers) MoS 2 channel. Using this, an optimized MOS capacitor geometry is identified. By comparing the model with experimental data, we obtain exponential defect states ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mi>D</mml:mi> <mml:mrow> <mml:mi>i</mml:mi> <mml:mi>t</mml:mi> <mml:mo>,</mml:mo> <mml:mi>p</mml:mi> <mml:mi>e</mml:mi> <mml:mi>a</mml:mi> <mml:mi>k</mml:mi> </mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>3</mml:mn> <mml:mo>−</mml:mo> <mml:mn>4</mml:mn> <mml:mo>×</mml:mo> <mml:msup> <mml:mn>10</mml:mn> <mml:mrow> <mml:mn>13</mml:mn> </mml:mrow> </mml:msup> </mml:math> cm −2 eV −1 , σ = 0.12 − 0.08 eV) originating from the conduction band for MoS 2 on 4 nm HfO 2 and 21 nm SrTiO 3 , respectively. The model successfully captures the length dependence of MOS capacitors and the static and dynamic behavior of D it .