Thermal stability of HfOxNy gate dielectrics on p-GaAs substrates

The structural, electrical and interfacial properties of metal-oxide–semiconductor (MOS) capacitors with hafnium-oxynitride (HfOxNy) 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 HfOxNy 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 VG = −1 V was achieved after 600 °C annealing for an EOT of 3.9 nm. The thermal stability and charge trapping behavior of the HfOxNy/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