Combined electrical transport and capacitance spectroscopy of a ${\mathrm{MoS_2-LiNbO_3}}$ field effect transistor

TL;DR

This study combines electrical transport and capacitance spectroscopy to analyze a MoS2-LiNbO3 FET, revealing more accurate electron mobility measurements and validating a two-dimensional free electron model for gate voltage dependence.

Contribution

It introduces a combined measurement approach that improves electron mobility estimation and confirms the applicability of the 2D free electron model in MoS2-based FETs.

Findings

Capacitance measurements match the 2D free electron model.

Combined analysis yields lower, more accurate mobility values.

Method enhances understanding of gate voltage effects on electron density.

Abstract

We have measured both the current-voltage ($I_\mathrm{SD}$-$V_\mathrm{GS}$) and capacitance-voltage ($C$-$V_\mathrm{GS}$) characteristics of a $\mathrm{MoS_2-LiNbO_3}$ field effect transistor. From the measured capacitance we calculate the electron surface density and show that its gate voltage dependence follows the theoretical prediction resulting from the two-dimensional free electron model. This model allows us to fit the measured $I_\mathrm{SD}$-$V_\mathrm{GS}$ characteristics over the \emph{entire range} of $V_\mathrm{GS}$. Combining this experimental result with the measured current-voltage characteristics, we determine the field effect mobility as a function of gate voltage. We show that for our device this improved combined approach yields significantly smaller values (more than a factor of 4) of the electron mobility than the conventional analysis of the current-voltage characteristics only.