▎ 摘　　要

The device physics and performance of heterojunction (HJ) graphene-nanoribbon (GNR) tunneling field-effect transistors (TFETs) with different designs are investigated in this letter. Due to the width-dependent energy bandgap (E-G), a single GNR with spatially dependent width naturally yields an HJ structure to improve the device performance of a GNR TFET. By adding a small-E-G region in the channel near the source and a large-E-G region in the middle of the channel, the ON-and OFF-state currents (I-ON and I-OFF, respectively) can be tuned. Last, we have studied the effect of channel length scaling on an HJ GNR TFET, and it has been observed that an I-ON/I-OFF ratio of four orders of magnitude can be achieved with a channel length of 10 nm and a drain bias of 0.6 V.