OPTICAL PROPERTIES OF PULSED LASER DEPOSITED MANGANESE OXIDE THIN FILMS DETERMINED BY INFRARED SPECTROSCOPY

Abstract

Despite recent advances in nonlinear optical techniques for examining elementary excitations in semiconductors, infrared spectroscopy remains an attractive approach to nondestructive and quantitative measurement of relevant optoelectronic properties of materials, because of it is readily available as an experimental technique and that relatively simple theories can be used to describe the material’s response to an infrared wavelength excitation. The optical and electronic behavior of semiconductors are determined by two major properties particularly energy gap and refractive index, the determination of which is necessary in the design of optoelectronic devices. In this work, we use fourier-transform infrared spectroscopy in reflective mode for the optical characterization of the manganese oxide thin films synthesized on silicon substrates using Pulsed Laser Deposition, under different experimental operating conditions, such as deposition temperature and pressure. The IR reflectivity measurements are analyzed by combining the Kramers-Kronig conversion theorem with the Fresnel equations for the reflectivity of a multilayer structure. The technique used allowed to separate the dielectric properties of the substrate from the dielectric properties of the thin films. The results obtained show that the index of refraction of the films depends on growth conditions and in some instances, high values of the index of refraction in the infrared region can be obtained. This result paves the way for interesting technological applications for these films as waveguides and other nanophotonic devices.