Longitudinal optical phonon-plasmon coupling in InSb and InAs

The longitudinal optical phonon-plasmon interaction theory of Varga is shown to be applicable to InSb and InAs in the infrared region. The theoretical reflectivity versus wavelength for InSb and InAs samples are compared with experimental data and the agreement between theory and experiment is particularly good for high dopant concentrations. The effective masses calculated from the values of plasma frequencies that fit the reflection spectra show a good comparison with other data of InSb and InAs. Murray et al.'s theory works well to explain reflectivity minimum wavelength versus impurity concentration data of InSb, InAs and GaAs at high concentrations but fails at small concentrations. The two wavelength minima predicted by Varga's theory have also been determined and the results show quite good agreement with the experimental data of InSb and InAs even as ωsub(p)→ωsub(l) at low concentrations. (Auth.)