Nitrided HfTiON/Ga₂O₃(Gd₂O₃) as stacked gate dielectric for GaAs MOS applications

Abstract

GaAs metal–oxide–semiconductor (MOS) capacitors with HfTiON as a gate dielectric and Ga2O3(Gd2O3) (GGO) as an interlayer annealed in NH3 or N2 are fabricated, and their electrical properties are characterized. Experimental results show that the HfTiON/GGO/GaAs MOS device annealed in NH3 exhibits a low interface-state density (1.1 × 1012 cm−2 eV−1), a small gate leakage current (1.66 × 10−4 A cm−2 at Vg = Vfb + 1 V), a large equivalent dielectric constant (25.7), and a good capacitance–voltage behavior. All these should be attributed to the fact that the GGO interlayer and postdeposition annealing in NH3 can effectively suppress the formation of interfacial Ga/As oxides and remove the excess As atoms at the GaAs surface, thus reducing the relevant defects at/near the GGO/GaAs interface.