Thermal stability of HfO_xN_y gate dielectrics on p-GaAs substrates

The structural, electrical and interfacial properties of metal-oxide-semiconductor (MOS) capacitors with hafnium-oxynitride (HfO _xN_y) gate dielectrics on p-GaAs substrates were investigated with post-deposition annealing (PDA). X-ray photoelectron spectra (XPS) show the presence of nitrogen at the interface and the intensity increases with annealing temperatures. Although the defective Ga-oxide increases with temperatures, the presence of nitrogen stabilizes and modulates the interface trap by reducing the oxygen vacancy. The electrical characteristics of GaAs MOS devices with HfO_xN_y gate dielectric show low interface state density, frequency dispersion and hysteresis voltage even after annealing at 600 °C. The accumulation capacitance decreases with annealing temperatures due to the formation of a stable thick nitride interfacial layer. The leakage current density of ∼2.4 × 10^-6 A cm ^-2 at V_g = - 1 V was achieved after 600 °C annealing for an EOT of 3.9 nm. The thermal stability and charge trapping behavior of the HfO_xN_y/p-GaAs gate stack at a constant voltage and current stressing have exhibited good interface quality and high dielectric reliability, making the films suitable for GaAs-based complementary metal-oxide-semiconductor technology