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 Al2O3/Y2O3 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 107 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 × 1011 eV−1 cm−2 from our Al2O3/Y2O3/GaAs MOSFET, the lowest value among the planar (In)GaAs MOSFETs.