Gate oxide scaling down in HfO2-GaAs metal-oxide-semiconductor capacitor using germanium interfacial passivation layer

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 A, an equivalent oxide thickness (EOT) of 8.7 A was achieved with a low gate oxide leakage current density (J(g)) of (2-4)x10(-3) A/cm(2) at V-G-V-FB=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 A, an EOT of 20-22 A with J(g) of (2-4)x10(-6) A/cm(2) at V-G-V-FB=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. (C) 2007 American Institute of Physics.