Broadening of photoluminescence for inhomogeneous polar and non-polar InGaN/GaN quantum wells



The model of a ‘random’ quantum well (QW) [M. Gladysiewicz and R. Kudrawiec, J. Phys.: Condens. Matter 22, 485801 (2010)] has been applied to generate low temperature photoluminescence (PL) spectra for polar and non-polar InGaN QWs dedicated for blue and green emitters. In order to simulate QW inhomogeneities in this model, 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 mean value. In PL spectrum such a QW is represented by a Lorentz-like peak with the homogeneous broadening. For an inhomogeneous QW the PL spectrum is built from such PL peaks obtained for thousands random QWs. Such an approach allows to investigate the influence of QW inhomogeneities on the broadening of the PL. In this paper it is clearly shown that the polarization-related electric field enhances the broadening of the PL. A reduction of built-in electric field in InGaN QWs can be a promising way to improve the homogeneity of light emission from this system. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)