Characterization Of Reactively Rf-Sputtered Tantalum Oxide Waveguides

Abstract

Relationships of the waveguide properties of the reactively rf-sputtered tantalum oxide films with a variety of sputtering conditions have been studied. Sputtering gas pressure, gas composition, rf power, and substrate temperature have been varied for studying the effects on the refractive index, deposition rate, structure, and atomic composition of the deposited tantalum oxide films. For a certain total pressure and gas composition of the reactive atmosphere, the deposition rate and refractive index will reach a peak value; while, for lower or higher total pressure and/or composition, the deposition rate and refractive index will decrease simultaneously. Increasing the substrate temperature will lead to films with higher refractive index. Increasing the sputtering rf power will increase the deposition rate, but the refractive index of the deposited films will be decreased. Strong correlations between the atomic composition, refractive index, and the optical loss have been observed. The larger the atomic ratio of oxygen to tantalum, the higher the refractive index, and the lower the optical loss of the fabricated samples.