Electronic structure and origin of intrinsic defects in sputtered HfTiO2 alloy dielectric on GaAs surface

Abstract

In this work, we have investigated the electronic structure and electrical properties of sputter-deposited high-k dielectrics grown on p-GaAs substrate with post-deposition annealing at 500 °C/N2 ambient. Capacitance-voltage results show that co-sputtered amorphous-HfTiO2 alloy dielectric can reduce interfacial dangling bonds. HRTEM and AR- X-ray photoelectron spectroscopy results confirmed the formation of a thin interfacial layer during sputter deposition. At the atomistic level, the surface reaction and electronic interface structure were investigated by density-functional theory (DFT) calculations. Using the HSE functional, theoretical calculations of bulk HfO2, a-TiO2, and HfTiO2 band gaps are found to be 5.27, 2.61, and 4.03 eV, respectively.