Theory of photoluminescence line shape due to interfacial quality in quantum well structures

Abstract

We have developed a simple theory to understand the role of interfacial quality in the line shape of photoluminescence spectra in quantum wells. The interface is described in terms of microscopic fluctuations δ1 and δ2, where δ1 is the local fluctuation in the well width and δ2 is the lateral correlated extent of the fluctuation. We make use of Lifshitz theory of disordered alloys to determine the probability of distribution of fluctuations in the well size over the extent of the optical probe, i.e., the exciton. The line shape is then calculated from this probability distribution. Both δ1 and δ2 are found to be important in controlling the linewidths in quantum wells. The use of this quantitative theory to characterize the microscopic nature of interfaces is discussed.

Distribution of oscillator strengths for recombination of localised excitons in two dimensions

“…Exciton absorption and emission lines in these two-dimensional samples are typically much broader than in three-dimensional systems. This is often due to fluctuations in the width of the layer: there is a 'quantum confinement' contribution to the energy of the exciton, which is a decreasing function E(w) of the layer width w, and which is analogous to the ground state energy π 2h2 /2mw 2 of a particle trapped in a one-dimensional potential well [3,4].…”

Magneto-optical studies of the correlation between interface microroughness parameters and the photoluminescence line shape inGaAs/Ga0.7Al0.3Oliveira1, Menêses2, Silva3 1999Phys. Rev. B18140View full textAdd to dashboardCite

“…Our conclusion is based on the comparison between the FWHM measured directly from our magneto-optical PL spectra and the theoretical FWHM obtained from the Singh and Bajaj model, which is based on the flat island picture and on thermodynamic arguments. 1,14,15 The sample investigated in this work was one multiple quantum well structure grown by molecular beam epitaxy ͑MBE͒ on top of a GaAs ͑100͒ substrate. The structure starts with a 1.0-m-thick undoped GaAs buffer layer followed by the active region, composed by 20 GaAs/Ga 0.7 Al 0.3 As quan-PHYSICAL REVIEW B 15 JULY 1999-I VOLUME 60, NUMBER 3 PRB 60 0163-1829/99/60͑3͒/1519͑4͒/$15.00 1519 ©1999 The American Physical Society tum wells.…”

High quality interfaces in GaAs–AlAs quantum wells determined from high resolution photoluminescence

“…Also given in Table I are the experimentally observed values of the energy separations. A theoretical model that explains fractional monolayer variations in well size was developed by Singh et al 7,11,12 According to the model, the interface can be represented by GaAs and AlAs-like two-dimensional ͑2D͒ islands. For simplicity we have placed all of the interface structure at the AlAs on GaAs interface.…”