GaAs MOSFETs with in situ Y2O3 dielectric: attainment of nearly thermally limited subthreshold slope and enhanced drain current via accumulation

Abstract Planar GaAs(100) depletion-mode (D-mode) MOSFETs as passivated with in situ deposited Al 2 O 3 /Y 2 O 3 dielectric have shown enhancement of the drain current by 167% and 333% as the gate voltage ( V g ) increased from flat-band voltage ( V fb ), namely V g = V fb = 0.5 V to V g = 2 V and V g = 4 V, respectively, much higher than those in the previously published GaAs-based D-mode MOSFETs. In addition, we have achieved a high I on / I off of 10 7 and a subthreshold slope (SS) of 63 mV dec −1 , which approaches the thermal limit of 60 mV dec −1 at 300 K and is the record-low value among planar (In)GaAs MOSFETs. Moreover, using the measured SS data, we have deduced an interfacial trap density ( D it ) of 4.1 × 10 11 eV −1 cm −2 from our Al 2 O 3 /Y 2 O 3 /GaAs MOSFET, the lowest value among the planar (In)GaAs MOSFETs.