Observation of Current Enhancement Due to Drain-Induced Drain Tunneling in Tunnel Field-Effect Transistors

It is well-established that a tunnel field-effect transistor (TFET) may or may not show a good drain current saturation in its output characteristics, depending upon its device structure. In this paper, we report for the first time a new phenomenon in double-gate silicon TFETs, which causes a sudden increase in its drain current at larger drain voltages, independent of whether they show a good output current saturation or not in the initial portion of their output characteristics. It is observed that larger drain voltages result in band-to-band tunneling of the electrons occurring from the valance band of the channel to the conduction band of the drain, which causes such sudden increase of drain current. (C) 2012 The Japan Society of Applied Physics