INSULATING PROPERTIES OF W-DOPED Ga2O3 FILMS GROWN ON Si SUBSTRATE FOR LOW-K APPLICATIONS

Set of W-doped Ga2O3 thin films were prepared by vacuum evaporation method on glass and silicon substrates. The molar ratio of dopant W to host Ga was measured with the X-ray fluorescence (XRF) micro radiographic analysis to be 9.6%, 13.4%, 18.2%, 22.7%, and 30.4%. The crystalline state of the oxide films was determined by the X-ray diffraction method (XRD). All the oxide films deposited on silicon substrate have amorphous structure while those deposited on glass substrate have crystalline - Ga2O3 structure, which shows that the WO3 material was totally doped in the lattice of Ga2O3 forming solid solution (SS). The electrical properties of the prepared SS's were studied for samples made in form of MOS, Au/SS/Si configuration. It was observed that W-doping with certain level reduces the dielectric constant of Ga2O3:W film to less than that of SiO2, i. e. the doping with W turns the high-k gallium oxide into low-k dielectric material. The dielectric relaxation of the SS was studied through the complex dielectric permittivity (epsilon)* from which (epsilon)infinity(') and the most probable relaxation time ( ) as a function of W-doping level was determined.