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We present gallium arsenide (GaAs) metal-oxide-semiconductor capacitors (MOSCAPs) with a thin HfO2 gate dielectric and a thin germanium nitride (GexNy) interfacial passivation layer (IPL). TaN/HfO2/GexNy/GaAs MOSCAPs show a low interface state density and a thin equivalent oxide thickness (1.6 nm). Compared to GaAs MOSCAPs with germanium (Ge) IPL, the GexNy IPL has a smaller slow trap density, which is confirmed by improved C-V characteristics without humps near the flatband voltage. The lower rate of flatband voltage shift and gate leakage decreasing under constant gate voltage stress were also demonstrated in GaAs MOSCAPs with GexNy IPL than the Ge IPL. [ABSTRACT FROM AUTHOR]

The primary goal of this work is to investigate the capability of gate oxide scaling down in HfO2-based GaAs metal-oxide-semiconductor capacitor (MOSCAP) using a thin germanium (Ge) interfacial passivation layer (IPL). With HfO2 of 45–50 Å, an equivalent oxide thickness (EOT) of 8.7 Å was achieved with a low gate oxide leakage current density (Jg) of (2–4)×10-3 A/cm2 at VG-VFB=1.0 V. This is the thinnest EOT thickness ever reported for high-k III-V MOSCAPs. On the other hand, with thicker HfO2 of 100–110 Å, an EOT of 20–22 Å with Jg of (2–4)×10-6 A/cm2 at VG-VFB=1.0 V was attained. In addition, breakdown voltages of gate oxide and hysteresis characteristics according to different thicknesses of HfO2 were studied. The results indicate that a Ge IPL and thin HfO2 enable excellent gate oxide scaling down in GaAs system. [ABSTRACT FROM AUTHOR]