Electrical and Interfacial Characterization of Atomic Layer Deposited High- κ Gate Dielectrics on GaAs for Advanced CMOS Devices

In this paper, electrical and interfacial properties of MOS capacitors with atomic layer deposited (ALD)Al₂O₃,HfO₂, and HfAlO gate dielectrics on sulfur-passivated (S-passivated) GaAs substrates were investigated. HfAlO on p-type GaAs has shown superior electrical properties overAl₂O₃orHfO₂on GaAs, and it is attributed to the reduction of the Ga–O formation at the interfacial layer. HfAlO on p-type GaAs exhibits the best electrical properties after postdeposition annealing (PDA) at 500∘C. It is found that PDA, at above 500∘C, causes a significant amount of Ga and As out-diffusion into the high-κdielectric, which degrades the interface, as well as bulk high-κproperties.