Liquid-Phase Deposited TiO2 Thin Films on GaN

TiO₂ films deposited on GaN layers at room temperature through a simple and low-cost liquid-phase deposition (LPD) method are investigated. The deposition rate is 70 nm/hr. X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) are used to analyze chemical composition. Upon annealing under an atmosphere of high purity N₂, the crystalline phase of TiO₂ is transformed from the amorphous to the anatase and rutile phases. Electrical characteristics show the leakage current is about 1.01x10^-7 A/cm² at 1 MV/cm, and the breakdown field is more than 6.5 MV/cm. Moreover, the dielectric constant is about 24.4, and D_it can be 7.48 x 10¹¹ cm^-2eV^-1 from C-V measurement. AlGaN/GaN MOSHEMTs with TiO₂ gate dielectric and HEMTs are also fabricated for comparison.