Twist angle dependence of graphene-stacked junction characteristics

Abstract

Vertically stacked graphene diodes are fabricated using epitaxially grown graphene with twist angles ranging from 0° to 30°. Their switching behavior and negative differential conductance are observed at all the measured angles. The junction conductance in the initial state does not indicate clear angle dependence and is almost constant, i.e., 231 µS for all devices. The junction conductance in the high-bias region exhibits a steep peak at 12°. The on/off ratio of the stacked junction diode indicates a maximum value of 142 at 12°. Therefore, the fabricated stacked graphene device with a simple structure exhibits strong nonlinear electrical properties and negative differential conductance at all twist angles. The on/off ratio of the stacked junction diodes is controlled by the twist angle between two single-crystal graphene layers.