We have demonstrated a record low 85 mV/dec subthreshold slope (SS) at 300 K among the planar inversion-channel InGaAs metal-oxide-semiconductor field-effect transistors (MOSFETs). Our MOSFETs using in-situ deposited Al2O3/Y2O3 as a gate dielectric were fabricated with a self-aligned inversion-channel metal-gate-first process. The temperature-dependent transfer characteristics showed a linear reduction of SS versus temperature, with attainment of an SS of 22 mV/dec at 77 K; the value is comparable to that of the state-of-the-art InGaAs FinFET. The slope factor of SS with temperature (m) is 1.33, which is lower than those reported in the planar InGaAs MOSFETs.

By in situ depositing Y2O3 on a pristine p-In0.53Ga0.47As surface under ultra-high vacuum, we have attained a low interfacial trap density (Dit) of (2–5) × 1011 eV−1cm−2 from the mid-gap to the valence band edge. The Dit values were extracted from the conductance contours measured from 300 K to 77 K. The small frequency dispersions of 1.2%/dec (300 K) and 0.28%/dec (77 K) in the accumulation region of the capacitance–voltage (CV) characteristics and very small frequency-dependent flatband voltage shifts of 0.021 V/dec (300 K) and 0.011 V/dec (77 K) indicate low border trap densities and low Dit's; these experimental results have not been achieved in previous reports of oxide/p-In0.53Ga0.47As. The Y2O3/p-In0.53Ga0.47As heterostructure also exhibited a high thermal stability of 800 °C, as observed by the low Dit values, small CV frequency dispersions, and an abrupt interface without inter-diffusion in cross-sectional scanning transmission electron microscopy images. Our work has demonstrated a long-sought remedy for the effective passivation of p-type In0.53Ga0.47As, paving the way to high-performance electronic and optoelectronic In0.53Ga0.47As devices.

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