High-Quality Interface in ${\rm Al}_{2}{\rm O}_{3}/{\rm GaN}/{\rm GaN}/{\rm AlGaN}/{\rm GaN}$ MIS Structures With In Situ Pre-Gate Plasma Nitridation

We report an in situ low-damage pre-gate treatment technology in an atomic layer deposition (ALD) system prior to the ALD-
${\rm Al}_{2}{\rm O}_{3}$
deposition, to realize high-quality
${\rm Al}_{2}{\rm O}_{3}/{\rm III}\hbox{-}{\rm nitride}$
(III-N) interface. The technology effectively removes the poor quality native oxide on the III-N surface while forming an ultrathin monocrystal-like nitridation interlayer (NIL) between
${\rm Al}_{2}{\rm O}_{3}$
and III-N surface. With the pre-gate treatment technology, high-performance
${\rm Al}_{2}{\rm O}_{3}({\rm NIL})/{\rm GaN}/{\rm AlGaN}/{\rm GaN}$
metal–insulator–semiconductor high-electron-mobility transistors are demonstrated, exhibiting well-behaved electrical characteristics including suppressed gate leakage current, a small subthreshold slope of
${\sim}{\rm 64}~{\rm mV/dec}$
, and a small hysteresis of
${\sim}{\rm 0.09}~{\rm V}$
.