Enhanced anti-Stokes photoluminescence in aGaAs/Al0.17Ga0.83Assingle quantum well with growth islands

Abstract

Photoluminescence spectra of a ${\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}/\mathrm{A}\mathrm{l}}_{0.17}{\mathrm{Ga}}_{0.83}\mathrm{As}$ single quantum well with growth islands are investigated in the Stokes as well as in the anti-Stokes regime. While at 5 K only luminescence at energies below the excitation energy can be detected, above 20 K also anti-Stokes luminescence is observed. A rate-equation model reproduces the observed dependence of the intensities of Stokes and anti-Stokes luminescence on temperature and, qualitatively, on the areal density of the growth islands and the properties of the diffusion-assisted transfer between them. The geometrical properties can enhance the anti-Stokes luminescence by almost one order of magnitude.