physica status solidi (b) · 1973 · 67 citations · 15 references
Natural SciencesMaterials SciencePhysicsMaterials CharacterizationMaterials PhysicsOptical MaterialsElectronic Band StructureElectronic Material CharacterizationOptical Properties Of MaterialsOptical Properties Of SemiconductorsOptical Properties Of SolidsThin Film Optical PropertiesCharge Carrier DensityEnergy Band GapOptical Band GapOptical CharacterizationOptical ConstantsOptical PropertiesReflectanceSemiconductor Characterization
Abstract The reflectance spectra of bulk samples of the germanium telluride (GeTe) system have been measured in the wavelength range 13 to 0.2 μm. The principal optical constants of the system have been obtained by inverting the spectra using the Kramers‐Kronig technique. Two distinct types of behavior were encountered depending on whether or not a sample exhibited a free carrier absorption peak. Samples rich in germanium lacked such a peak and had optical properties very similar to amorphous GeTe films. Tellurium rich samples always showed a large free carrier peak and from analysis of their optical Constants the effective mass and optical energy gap of the system was obtained. The variation of the effective mass and energy gap with composition (i.e., hole carrier density) is consistent with the existence of two sets of valence‐conduction bands in the system. A multiple band model based on experimental and theoretical data is outlined and its parameters are found to be in good agreement with published work.
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