Comparison of interfacial and electrical properties between Al2O3 and ZnO as interface passivation layer of GaAs MOS device with HfTiO gate dielectric

GaAs metal—oxide—semiconductor (MOS) capacitors with HfTiO as the gate dielectric and Al 2 O 3 or ZnO as the interface passivation layer (IPL) are fabricated. X-ray photoelectron spectroscopy reveals that the Al 2 O 3 IPL is more effective in suppressing the formation of native oxides and As diffusion than the ZnO IPL. Consequently, experimental results show that the device with Al 2 O 3 IPL exhibits better interfacial and electrical properties than the device with ZnO IPL: lower interface-state density (7.2 × 10 12 eV -1 cm -2 ), lower leakage current density (3.60 × 10 -7 A/cm 2 at V g = 1 V) and good C—V behavior.