Heterojunction-Free GaN Nanochannel FinFETs With High Performance

Heavily doped GaN nanochannel fin-shaped field-effect transistors (FinFETs) without heterojunction have been fabricated and characterized for the first time. Simplified pragmatical technology for GaN epitaxial growth and FinFET process was used to achieve nanodevices with a channel width from 40 to 100 nm and a gate length of 1
$\mu\hbox{m}$
. They exhibit excellent on-state performance, such as maximum drain current of 670 mA/mm and maximum transconductance of 168 mS/mm. Record off-state performance was measured: extremely low leakage current of
$\sim\!\!\hbox{10}^{-11}\ \hbox{mA}$
and source–drain breakdown voltage of
$\sim$
280 V. The subthreshold slope of 68 mV/decade is close to the theoretical limit (60 mV/decade, so far achieved only in SOI MOSFETs) and leads to very high
$I_{\rm on}/I_{\rm off}$
ratio of
$\hbox{10}^{8} {-} \hbox{10}^{9}$
. The proposed heterojunction-free nanochannel GaN FinFET is a very promising candidate not only for high-performance and high-speed integrated circuits but also for high-power applications.