Self-aligned inversion-channel In0.75Ga0.25As metal–oxide–semiconductor field-effect-transistors using UHV-Al2O3/Ga2O3(Gd2O3) and ALD-Al2O3 as gate dielectrics

High-performance self-aligned inversion-channel In0.75Ga0.25As n-MOSFETs using in situ ultra-high-vacuum (UHV) deposited Al2O3/Ga2O3(Gd2O3) [GGO] and ex-situ atomic-layer-deposited (ALD) Al2O3 as gate dielectrics have been fabricated. Both devices exhibit high drain currents and transconductances. A 1.2 μm-gate-length In0.75Ga0.25As MOSFET using Al2O3 (2 nm-thick)/GGO (13 nm-thick) gate dielectric demonstrated a maximum drain current of 970 μA/μm, a peak transconductance of 410 μS/μm, and a peak mobility of 1560 cm2/V s. A maximum drain current of 740 μA/μm and a peak transconductance of 325 μS/μm were exhibited by a 1 μm-gate-length In0.75Ga0.25As MOSFET using ALD-Al2O3 (6 nm-thick). A comparison between the inversion-channel InGaAs MOSFETs with gate dielectrics using the UHV- and ALD-approaches, and fabricated using the same self-aligned process, was carried out to provide insights for achieving InGaAs MOSFETs with even higher device performances. The comparison in the device performances was extended to cover representative enhancement-mode InGaAs MOSFETs, including self-aligned inversion-channel, non-self-aligned inversion-channel, and flat-band, or buried channel-type of E-mode (non inversion-channel) III–V devices.