Effects of Ti incorporation on the interface properties and band alignment of HfTaOx thin films on sulfur passivated GaAs

Thin HfTaOx and HfTaTiOx gate dielectrics (similar to 7-8 nm) have been rf sputter-deposited on sulfur passivated GaAs. Our experimental results suggest that the formation of Ga-O at GaAs surface and As diffusion in dielectric may be effectively controlled by Ti incorporation. Possibility of tailoring of band alignment via Ti incorporation is shown. Valence band offsets of 2.6 +/- 0.05 and 2.68 +/- 0.05 eV and conduction-band offsets of 1.43 +/- 0.05 and 1.05 +/- 0.05 eV were found for HfTaOx (E-g similar to 5.45 eV) and HfTaTiOx (E-g similar to 5.15 eV), respectively. (C) 2011 American Institute of Physics. [doi:10.1063/1.3536520]