GaAs Enhancement-Mode NMOSFETs Enabled by Atomic Layer Epitaxial $\hbox{La}_{1.8}\hbox{Y}_{0.2}\hbox{O}_{3}$ as Dielectric

We demonstrate high-performance enhancement-mode (E-mode) GaAs NMOSFETs with an epitaxial gate dielectric layer of
$\hbox{La}_{1.8}\hbox{Y}_{0.2}\hbox{O}_{3}$
grown by atomic layer epitaxy (ALE) on GaAs(111)A substrates. A 0.5-
$\mu\hbox{m}$
-gate-length device has a record-high maximum drain current of 336 mA/mm for surface-channel E-mode GaAs NMOSFETs, a peak intrinsic transconductance of 210 mS/mm, a subthreshold swing of 97 mV/dec, and an
$I_{\rm ON}/I_{\rm OFF}$
ratio larger than
$\hbox{10}^{7}$
. The thermal stability of the single-crystalline
$\hbox{La}_{1.8}\hbox{Y}_{0.2}\hbox{O}_{3}$
–single-crystalline GaAs interface is investigated by capacitance–voltage (
$C{-}V$
) and conductance–voltage
$(G{-}V)$
analysis. High-temperature annealing is found to be effective to reduce
$D_{\rm it}$
.