Photoconductivity Associated with Landau Structure in GaSb

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Abstract
A detailed study is made of the photoconductivity of thick stress-free GaSb samples in a magnetic field at 4.2 K. The characteristics of the spectra are found to depend strongly on the surface conditions. "Ideal" surface conditions enhance the Landau oscillations at the expense of the phonon type of oscillations and well-defined spectral structures are observed corresponding to interband transitions as high as the twenty-second Landau subband. The appearance in the photoconductivity spectra of thick specimens of oscillations related to structures in the absorption coefficient is explained by variations in the photosensitivity with penetration depth. Excitonic participation is indicated. The observed structures are compared to the stress-modulated magnetoreflectance data of Reine, Aggarwal, and Lax and the differences are discussed. Following the above authors, the results are analyzed in terms of the coupled-band theory of Pidgeon and Brown by means of an iterative computer program in order to determine the pertinent band parameters.