The method of angular photonic correlations of spontaneous emission is introduced as an experimental, purely optical scheme to characterize disorder in semiconductor nanostructures. The theoretical expression for the angular correlations is derived and numerically evaluated for a model system. The results demonstrate how the proposed experimental method yields direct information about the spatial distribution of the relevant states and thus on the disorder present in the system.
A microscopic theory for the luminescence of ordered semiconductors is modified to describe photoluminescence of strongly disordered semiconductors. The approach includes both diagonal disorder and the many-body Coulomb interaction. As a case study, the light emission of a correlated plasma is investigated numerically for a one-dimensional two-band tight-binding model. The band structure of the underlying ordered system is assumed to correspond to either a direct or an indirect semiconductor. In particular, luminescence and absorption spectra are computed for various levels of disorder and sample temperature to determine thermodynamic relations, the Stokes shift, and the radiative lifetime distribution.
PACS 72.80. Ng, 78.40.Pg From the recent analysis of the potential fluctuations in disordered semiconductors on the basis of optical and transport measurements [1] it was concluded that these two different kinds of phenomena evidence extremely different energy scales of the random potential in the same sample. We resolve this puzzle using for the analysis of experimental data the well-known theories of transport and optical absorption in a disordered system with long-range potential fluctuations, caused by charged impurities [2,3]. The key point in our consideration is the essential difference between the density of states caused by the longrange fluctuations and the shape of the absorption coefficient. The latter is known to depend essentially not only on the fluctuation probability but also on the tunnelling efficiency of the optically excited electrons in the potential relief provided by the fluctuations [2].
In a recent publication [Phys. Rev. Lett. 97, 227402 (2006), arXiv:cond-mat/0611411], it has been demonstrated numerically that a long-range disorder potential in semiconductor quantum wells can be reconstructed reliably via single-photon interferometry of spontaneously emitted light.In the present paper, a simplified analytical model of independent two-level systems is presented in order to study the reconstruction procedure in more detail. With the help of this model, the measured photon correlations can be calculated analytically and the influence of parameters such as the disorder length scale, the wavelength of the used light, or the spotsize can be investigated systematically. Furthermore, the relation between the proposed angle-resolved single-photon correlations and the disorder potential can be understood and the measured signal is expected to be closely related to the characteristic strength and length scale of the disorder.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.