# Reversible control of interface-water induced carrier density in graphene-on-SiO$_2$ by thermal cycling under gate-voltage

## TL;DR

This study demonstrates that thermal cycling under gate voltage can reversibly control the carrier density in graphene on SiO₂ by modulating interface water, offering a potential method for memory device applications.

## Contribution

It introduces a reversible method to control graphene carrier density via thermal cycling, independent of the gate electric field, by manipulating interface water/oxygen species.

## Key findings

- Carrier density hysteresis vanishes below 250 K
- Thermal cycling at different gate voltages reversibly alters carrier density
- Dry interfaces show increased hysteresis upon heating above room temperature

## Abstract

A reversible handle on graphene carrier density, other than the gate electric field, is desirable for memory applications of graphene. Our experiments show that the commonly observed carrier density hysteresis in graphene on SiO$_2$ due to interface water/oxygen vanishes at temperatures below 250 K. The state of these species, which affects the graphene carrier density, at low temperatures can be reversibly controlled by thermal cycling to room temperature at different gate voltages. Further, devices prepared with relatively dry interface, and thus showing negligible hysteresis at room temperature, show a marked increase in hysteresis on heating above room temperature. Thus thermal-cycling, to high temperatures and under gate-voltage, provides a reversible handle on carrier density. These results are discussed in terms of temperature and interface-water density dependence of redox-reaction kinetics.