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Many-Body Effects on Temperature-Dependence of the Interband Absorption in Quantum Wells
Published online by Cambridge University Press: 21 February 2011
Abstract
A many-body theory is presented for the interband absorption in a pseudomorphic GaAlAs/InGaAs/GaAs modulation doped quantum well. The electron-electron interaction in a degenerate Fermi sea is calculated in the self-consistent Hartree approximation. In addition, the binding energy within an electron-hole pair is included in the ladder approximation as a vertex correction to the response function. In our theory, the coupling between excitons is calculated in the generalized random-phase approximation (RPA). Our numerical results for the temperature-dependence of the absorption peaks at the Fermi edge (low temperature) and the band edge (room temperature) compare well with available experimental data obtained using contactless photoreflectance techniques. At low temperatures, our theory shows that there are important modifications to the single-particle model. We extract the Fermi energy by fitting our calculated results to the thermally broadened lineshape of the absorption spectrum. As a consequence, the electron density of the quantum wells can be accurately determined by means of this contactless, non-destructive, rapid and simple characterization method. Moreover, information on the alloy composition, built-in electric field and the interface stress can also be obtained.
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- Copyright © Materials Research Society 1994