Aluminium oxynitride thin films based optical filter for biomolecules analysis in biological fluids

Abstract

The proposed optical filter is based on functionally graded Aluminium oxynitride thin films, deposited by DC reactive magnetron sputtering. Variations on the concentration of Aluminium, Oxygen and Nitrogen allows the development of optical filters with variation of refraction index along the thickness of the material. Presently, we have obtained refractive indexes between 1.6 and 2.3. These filters do not impose the limitation to a maximum number of optical filters (like in the different sized cavities array), and it uses only one material where the tuning process would be programmed in the fabrication process. Therefore, this approach will allow wide optical band operation over the entire visible spectral range, which is a demanding requirement for on-chip absorption spectrophotometry