Experimental analysis of Ga2O3:Ti films grown on Si and glass substrates

Ti-included gallium oxide (Ga2O3:Ti) thin films were prepared on glass and silicon substrates. The energy dispersion X-ray spectroscopy (EDX) method was used to measure the Ti inclusion level, which was 1.0%, 1.5%, 2.0%, 4.2%, 6.6%, 10.4%, 15.7%, and 27.6%. The X-ray diffraction (XRD) method was used to study the crystalline structure of the films. The oxide films grown on silicon substrate have amorphous structure while those oxide films grown on glass substrate show crystalline Ga2O3 structure, which confirms that the titanium was dissolved in the lattice of Ga2O3 forming solid solution (SS). The insulating properties of the amorphous Ti-included Ga-oxide films were studied for samples made in form of MOS:Au/Ga2O3:Ti/Si configuration. It was observed that Ti inclusion of certain levels reduces the effective dielectric constant of Ga2O3:Ti film to less than that of SiO2, i.e. the inclusion of Ti turns the high-k gallium oxide dielectric into low-k insulator. The dielectric relaxation of the incorporated films was studied through the complex dielectric modulus M∗, from which the high-frequency dielectric constant ε∞′ and the most probable relaxation time (τ) as a function of Ti-inclusion level was determined. The optosensitivity of Ga2O3:Ti film was studied as a function of Ti inclusion. The temperature dependent of the dc-current leaks through Au/Ga2O3:Ti/Si, MOS arrangement predicts a red shift of the bandgap due to Ti doping.