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 over AL(2)O(3) or HfO2 on 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 degrees C. It is found that PDA, at above 500 degrees C, causes a significant amount of Ga and As out-diffusion into the high-kappa, dielectric, which degrades the interface, as well as bulk high-kappa properties.