Spectroscopic ellipsometry studies on various zinc oxide films deposited by ion beam sputtering at room temperature

Various zinc oxide films were deposited by ion-beam sputter deposition (IBSD) under different oxygen partial pressures (P-O2) at room temperature. The as-deposited ZnO films fabricated at P-O2 > 1.0 x 10(-4) Torr had poly-crystalline structures to absorb water on the surface at ambient condition. Simultaneously, the film surfaces were covered and smoothed by the surface layers formed with the water, hydroxyl (OH-) groups, and ZnO materials investigated by X-ray photoelectron spectroscopy (XPS). When the compositions of the surface layers were used in a multilayer fitting model of spectroscopic ellipsometry, the actual optical refractive index of the ZnO film deposited at P-O2 = 1.2 x 10(-4) Torr was found to be about 1.9618 at lambda = 550 nm. (C) 2012 Optical Society of America