Optical sensor with transparent conductive oxides electrodes for microposition detection applications

Abstract

This paper presents an optical sensor structure for microposition detection application using transparent electrodes of indium doped ZnO (IZO). The optical microsensor consists of two linear arrays of metal – semiconductor – metal (MSM) silicon photodetectors with IZO transparent electrodes integrated with a polymer optical waveguide. IZO layers with a thickness of 460–580 nm have been deposited by dc magnetron sputtering technique on silicon epitaxial wafers of 30–50 Ω cm resistivity and a thickness of 23 µm. Due to their high optical transmittance (> 90%) over the 0.4–0.9 µm spectral range, these layers contributed to an increased responsivity of the MSM photodiode structure of about 0.34 A/W, thus improving the optical position microsensor sensitivity.