Optical properties of (AlxGa1-x)(0.52)In0.48P at the crossover from a direct-gap to an indirect-gap semiconductor

U. Dörr, W. Schwarz, A. Wörner, R. Westphäling, A. Dinger, H. Kalt, D.J. Mowbray, M. Hopkinson, Wolfgang Werner Langbein

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    Abstract

    The optical properties and the dynamics of excitons and the electron-hole plasma have been studied in disordered (AlxGa1 – x)0.52In0.48P near to the direct-to-indirect band gap crossover. In particular we have investigated three epitaxial layers grown by solid-source molecular beam epitaxy with varying Al content x. Two of them have compositions in the immediate vicinity of the crossover point, the other is assigned to the indirect-gap regime. Both direct and indirect recombination processes contribute to the photon emission from the material. Since the relative importance of the different recombination processes depends strongly on temperature, excitation intensity, and excitation pulse duration, the processes can be identified by changing these parameters. As a result, we can determine the relative alignment of the conduction band minima and the distribution of the electrons among them. At high excitation levels the two crossover samples show stimulated emission at a photon energy of ~ 2.29 eV, i.e., in the green spectral range. Using the variable stripe length method, we find an optical gain of up to ~ 600 cm – 1 at excitation levels of ~ 350 kW/cm2. Stimulated emission involves direct recombination. This conclusion is reached from the experiments and from line-shape modeling, including a self-consistent treatment of populations and renormalization of the conduction band minima. ©1998 American Institute of Physics.
    Original languageEnglish
    JournalJournal of Applied Physics
    Volume83
    Issue number4
    Pages (from-to)2241-2249
    ISSN0021-8979
    DOIs
    Publication statusPublished - 1998

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    Copyright (1998) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.

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