A Unified Pervasive Linebroadening Function for Quantum Wells in Light Emitting Diodes

Abstract

The broadening functions for quantum wells in LEDs and laser diodes below the lasing threshold are examined. Inhomogeneous and homogeneous broadening mechanisms are included. Hydrogen-atom-like exciton and the electron-hole plasma recombination models are considered. Material disorder and the Urbach tail are reviewed as the main reasons for the inhomogeneous broadening. Charge carrier scattering and relaxation times in the conduction and valence bands are examined as the origin for the homogeneous lifetime broadening. Two homogeneous lineshapes are compared using the momentum relaxation times obtained from the electron and hole mobilities available for GaAs. In addition to crystal disorder, the mutual collision of charge carriers in the quantum wells is examined as the reason for the relaxation time shortening. The analogy to pressure broadening in gases is used to combine the proper homogeneous and inhomogeneous broadening functions to a unified quantum well lineshape.

Multiple low-energy excitons and optical response of d0 double perovskite Ba2ScTaOHimanshu1, Kumar2, Dey3 et al. 2022Physica B: Condensed Matter

“…To model this part of the spectrum, different models were considered: first, driven by the exponential tail of the absorption data in this energy window, we considered the simplistic view based on directallowed transitions without excitons. The band edge part of the data is modeled as an exponential tail, so called Urbach tail, usually ascribed to shallow traps and disorder [29,30]. The Urbach energy was obtained to be 114.42 meV from our room temperature data.…”