▎ 摘　　要

We found that the current-voltage characteristics of graphene transistors exhibit an intriguing feature-an abrupt change in the current near zero gate bias at temperatures above 500 K. The strength of this effect, which we refer to as the memory step by analogy with the memory dips-known phenomenon in electron glasses, depends on the rate of the gate voltage sweep. The slower the sweep, the more pronounced is the step in the current. Despite differences in examined graphene transistors, the memory step always appears at V-g approximate to 0 V. The observed memory steps are likely related to the slow relaxation processes in graphene. This new phenomenon in graphene can be used for applications in sensors and switches. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3596441]