The two timescales in the charge trapping mechanism for the hysteresis behavior in graphene field effect transistors

To understand the hysteresis phenomenon in the transfer characteristic curve of graphene field effect transistor is crucial to develop new graphene based sensors and memory devices. We investigated the hysteresis through a charging and discharging procedure and found that there exist two time constants with different timescales in the trapping mechanism. A fast trapping at the interface with a time constant of 0.68 s and a slow trapping in the bulk oxide with a time constant of 23.85 s were presented in our work. By identifying a linear relation between the interface trap densities and the gate voltage, we also found that the release of trapped charges was decided by the magnitude decrease of gate voltage instead of the voltage’s polarity switch. Based on the findings, a bi-resistive state memory prototype with a shorter charging time was realized at last.