Intensity dependent deflection spectroscopy for absorption measurements

Abstract

We report on a method for the characterization of optical absorption in semiconductors at photon energies below the bandgap energy. We use intensity dependent deflection spectroscopy to measure spatially resolved the optical absorption and to separate the occurring absorption mechanisms. To this end, we take advantage of the different intensity scaling of these mechanisms and extract the material parameters by fitting the intensity dependent absorption to a physical model. Our method enables a simple but sufficient determination of crucial optical loss properties (e.g. impurity related absorption and two-photon absorption) in various semiconductor systems, e.g. substrates for optical components or solar cells.