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Sub-60 mV/decade switching via high energy electrons tunneling in nanoscale gallium nitride field-effect transistors

Novel devices such as tunneling field-effect transistors (FETs) and ferroelectric FETs have been demonstrated to break the subthreshold swing (SS) limit with sub-60 mV/decade switching for further low voltage/low power applications. In this paper, SS of sub-60 mV/dec was firstly observed in InAlN/GaN high electron mobility transistors (HMETs): an average SS of 30 mV/dec over three orders of magnitude in drain-source (Ids) and a minimum point-by-point SS of 15 mV/dec were achieved in the InAlN/GaN HEMTs with gate length (Lg) of 40 nm. It is found that SS decreases with drain-source voltage (Vds) as well as Lg, and falls below 60 mV/dec when Lg < 100 nm. The decrease of SS as the device dimension scales down is attributed to the tunneling of high energy electrons from channel to the surface. The SS decreasing with the nanoscale gate length shows the great potential of the InAlN/GaN HEMTs to be applied in future logic switches.