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 $D_{\rm \it}$ .