Optimization of multiple physical phenomena through a universal metric in junctionless transistors

Abstract

The work reports on the identification and applicability of a universal metric to suppress gate induced off-state tunneling while preserving impact ionization triggered sub-60 mV/decade current transition and hysteresis in 25 nm Junctionless (JL) MOSFET. At shorter gate length limit, two contrasting physical mechanisms, namely, impact ionization and Band-to-Band Tunneling (BTBT), affect device functionality. Both these phenomenon are analyzed through the evaluation of the product of current density (J) and electric field (E), which defines power generated per unit volume in the device. Hysteresis, in forward and reverse sweeps of applied gate bias, can be accompanied by an undesirable increase in off-current due to BTBT, thus limiting the device performance. The work showcases the relevance of J.E optimization in 25 nm JL device to achieve a subthreshold swing (S) < 5 mV/decade along with a wider hysteresis window ~140 mV at a drain bias (Vds) of 1 V with suppressed off-state tunneling. © 2019 IEEE.