Broadening of interband transitions in InGaN quantum wells

Abstract

AbstractBroadening of interband transitions was calculated for inhomogeneous InGaN quantum wells (QWs) dedicated for emitters operating in green spectral range. In order to simulate inhomogeneities for InGaN QW system, it was assumed that the QW width, barrier widths and indium concentration vary with a Gaussian distribution where the nominal QW width, barrier widths and indium concentration correspond to the mean value in this distribution and their fluctuations correspond to the deviation from the main value. Calculations of QW transitions were performed within the electron effective mass approximation for a thousand of randomly generated InGaN QWs and next a histogram of the intensity of optical transitions was built from the result of these calculations. In this way the influence of the each parameter (QW width, barrier width, and indium concentration) on the broadening of interband transitions was considered independently and, finally, all the parameters were taken into account at the same time. The obtained spectrum of interband transitions was compared with experimental data for InGaN QWs (i.e., photoluminescence and contactless electroreflectance measurements). It was found that the large broadening of interband transitions in InGaN QWs results from the inhomogeneous distribution of QW sizes and indium concentration. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)