Observation of the "Memory Steps" in Graphene at Elevated Temperatures

TL;DR

This paper reports the discovery of a temperature-dependent 'memory step' in the current-voltage characteristics of graphene transistors at temperatures above 500 K, indicating slow relaxation processes and potential high-temperature applications.

Contribution

It introduces the novel observation of the 'memory step' in graphene at elevated temperatures, expanding understanding of electron transport phenomena in graphene devices.

Findings

Memory step appears near zero gate bias at T > 500 K

Effect depends on voltage sweep rate, more pronounced with slower sweeps

Reproducible and persists after device aging

Abstract

We found that the current-voltage characteristics of the single-layer graphene field-effect transistors exhibit an intriguing feature - an abrupt change of the current near zero gate bias at elevated temperatures T > 500 K. The strength of the effect - referred to as the "memory step" by analogy with the "memory dips" - known phenomenon in electron glasses - depends on the rate of the voltage sweep. The slower the sweep - the more pronounced is the step in the current. Despite differences in examined graphene transistor characteristics, the "memory step" always appears near zero gate bias. The effect is reproducible and preserved after device aging. A similar feature has been previously observed in electronic glasses albeit at cryogenic temperatures and with opposite dependence on the rate of the voltage sweep. The observed "memory step" can be related to the slow relaxation processes in graphene. This new characteristic of electron transport in graphene can be used for applications in high-temperature sensors and switches.