Refractive index dispersion of swift heavy ion irradiated BFO thin films using Surface Plasmon Resonance technique

Abstract

Swift heavy ion irradiation (SHI) is an effective technique to induce defects for possible modifications in the material properties. There is growing interest in studying the optical properties of multiferroic BiFeO3 (BFO) thin films for optoelectronic applications. In the present work, BFO thin films were prepared by sol–gel spin coating technique and were irradiated using the 15UD Pelletron accelerator with 100MeV Au9+ ions at a fluence of 1×1012ionscm−2. The as-grown films became rough and porous on ion irradiation. Surface Plasmon Resonance (SPR) technique has been identified as a highly sensitive and powerful technique for studying the optical properties of a dielectric material. Optical properties of BFO thin films, before and after irradiation were studied using SPR technique in Otto configuration. Refractive index is found to be decreasing from 2.27 to 2.14 on ion irradiation at a wavelength of 633nm. Refractive index dispersion of BFO thin film (from 405nm to 633nm) before and after ion radiation was examined.