HIGH-k GATE DIELECTRIC: AMORPHOUS Ta/La2O3 FILMS GROWN ON Si AT LOW PRESSURE
Abstract
In the present study, Ta/La2O3 films (La2O3 doped with Ta2O5) as a gate dielectric were prepared using a sol–gel method at low pressure. Ta/La2O3 film has some hopeful properties as a gate dielectric of logic device. The structure and morphology of Ta/La2O3 films were studied using X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM). Electrical properties of films were performed using capacitance–voltage (C–V) and current density-voltage (J–V) measurements. The optical bandgap of samples was studied by UV-visible optical absorbance measurement. The optical bandgap, Eopt, is determined from the absorbance spectra. The obtained results show that Ta/La2O3 film as a good gate dielectric has amorphous structure, good thermal stability, high dielectric constant (≈ 25), low leakage current and wide bandgap (≈ 4.7 eV).
