Aluminum oxynitride interfacial passivation layer for high-permittivity gate dielectric stack on gallium arsenide

The authors demonstrate a passivation technique for GaAs substrate by employing an aluminum oxynitride (AlON) interfacial passivation layer. X-ray photoelectron spectroscopy and transmission electron microscopy results show that the AlON interfacial passivation layer effectively suppresses the formation of Ga or As oxide during the gate dielectric deposition process. This enabled the fabrication of high quality GaAs n-channel metal-oxide-semiconductor capacitors with Hf_O2 gate dielectric and TaN metal gate electrode. The metal gate/high-k gate dielectric stack on GaAs demonstrated an equivalent SiO₂ thickness of 2.2nm and low leakage current density of 4.27×10^-4A /cm² at a gate bias equal to V_fb-1V. Excellent capacitance-voltage characteristics with low frequency dispersion (∼4%) were also obtained.