HfO2-based In0.53Ga0.47As MOSFETs (EOT≈10Å) using various interfacial dielectric layers

This paper compares device performance for In_0.53Ga_0.47As MOSFETs using single HfO₂ gate dielectric with stacked gate dielectrics using various interfacial layers between HfO₂ and In_0.53Ga_0.47As substrate including Al₂O₃, HfAlO_x, LaAlO_x, and LaHfO_x. Of the gate stacks studied, Al₂O₃/HfO₂, HfAlO_x/HfO₂, and LaAlO_x/HfO₂ bilayer gate dielectrics exhibit lower subthreshold swing, higher drive current and transconductance compared to single HfO₂ with similar equivalent oxide thickness (EOT) of about 10 Å. This is believed to be due to better interface quality between interfacial dielectrics and substrate, and confirmed by frequency dispersion and interface state density measurements. Using 10 Å HfAlO_x or LaAlO_x as the interface layer between HfO₂ and InGaAs substrate reduces the interface trap density, thus achieves higher drive current, channel mobility and lower subthreshold swing than single HfO₂ layer.