The study explored titanium dioxide (TiO2) on aluminum gallium arsenide (AlGaAs) prepared by liquid phase deposition (LPD) at 40 degrees C. The leakage current density was about 8.4 x 10(-6) A/cm(2) at 1 MV/cm. The interface trap density (D-it) and the flat-band voltage shift (Delta V-FB) were 2.3 x 10(12) cm(-2) eV(-1) and 1.2 V. respectively. After rapid thermal annealing (RTA) in the ambient N-2 at 350 degrees C for 1 min, the leakage current density, D-it, and Delta V-FB were improved to 2.4 x 10(-6) A/cm(2) at 1 MV/cm, 7.3 x 10(11) cm(-2) eV(-1), and 1.0 V, respectively. Finally, the study demonstrates the application to the AlGaAs/InGaAs metal-oxide-semiconductor pseudomorphic high-electron-mobility transistor (MOS-PHEMT). The results indicate the potential of the proposed device with a LPD-TiO2 gate oxide for power application. (C) 2011 Elsevier Ltd. All rights reserved.