Hysteresis of Electronic Transport in Graphene Transistors

TL;DR

This paper investigates the causes and characteristics of hysteresis in graphene transistors, revealing how environmental factors, layer number, and temperature influence their electrical behavior, with implications for sensing and memory applications.

Contribution

It identifies two distinct types of hysteresis in graphene transistors and explores how environmental and material factors affect their electrical properties.

Findings

Charge transfer causes positive hysteresis shifts.

Capacitive gating can induce negative hysteresis.

Environmental conditions influence hysteresis behavior.

Abstract

Graphene field effect transistors commonly comprise graphene flakes lying on SiO2 surfaces. The gate-voltage dependent conductance shows hysteresis depending on the gate sweeping rate/range. It is shown here that the transistors exhibit two different kinds of hysteresis in their electrical characteristics. Charge transfer causes a positive shift in the gate voltage of the minimum conductance, while capacitive gating can cause the negative shift of conductance with respect to gate voltage. The positive hysteretic phenomena decay with an increase of the number of layers in graphene flakes. Self-heating in helium atmosphere significantly removes adsorbates and reduces positive hysteresis. We also observed negative hysteresis in graphene devices at low temperature. It is also found that an ice layer on/under graphene has much stronger dipole moment than a water layer does. Mobile ions in the electrolyte gate and a polarity switch in the ferroelectric gate could also cause negative hysteresis in graphene transistors. These findings improved our understanding of the electrical response of graphene to its surroundings. The unique sensitivity to environment and related phenomena in graphene deserve further studies on nonvolatile memory, electrostatic detection and chemically driven applications.