S-shaped current-voltage characteristics of n+-i-n-n+ graphene field-effect transistors due the Coulomb drag of quasi-equilibrium electrons by ballistic electrons

TL;DR

This paper investigates how ballistic electron injection in graphene FETs causes Coulomb drag effects, leading to S-shaped current-voltage characteristics with potential applications in terahertz devices.

Contribution

It reveals the role of Coulomb drag from ballistic electrons in inducing nonlinear I-V characteristics in graphene FETs, a novel insight into their transport behavior.

Findings

S-shaped I-V characteristics observed in graphene FETs.

Negative differential conductivity enables hysteresis and filamentation.

Potential for terahertz frequency multiplication and detection.

Abstract

We demonstrate that the injection of the ballistic electrons into the two-dimensional electron plasma in lateral n$^+$-i-n-n$^+$ graphene field-effect transistors (G-FET) might lead to a substantial Coulomb drag of the quasi-equilibrium electrons due the violation of the Galilean and Lorentz invariance in the systems with a linear electron dispersion. This effect can result in the S-shaped current-voltage characteristics (IVs). The resulting negative differential conductivity enables the hysteresis effects and current filamentation that can be used for the implementation of voltage switching devices. Due to a strong nonlinearity of the IVs, the G-FETs can be used for an effective frequency multiplication and detection of terahertz radiation.