Theoretical studies of the influence of structural inhomogeneities on the radiative recombination time in polar InGaN quantum wells

The influence of two structural inhomogeneities (i.e., the quantum well width and indium concentration fluctuations) on the radiative recombination time (tau(r)) in polar InGaN quantum wells (QWs) was studied within the "random'' QW model [M. Gladysiewicz and R. Kudrawiec, J. Phys.: Condens. Matter 22, 485801 (2010)]. In this analysis it is assumed that the tau(r) is inversely proportional to the electron-hole overlap integral which can be calculated within the effective mass approximation. In order to simulate QW inhomogeneities in this model, it was assumed that the QW width and indium concentration vary with a Gaussian distribution where the nominal QW width and indium concentration correspond to the mean value in this distribution and their fluctuations correspond to the deviation from the main value. Obtained results clearly show that the variation of QW width in this system (the first type of QW inhomogeneities) leads to a non-linear dispersion of the tau(r) whereas the change in indium concentration (the second type of QW inhomogeneities) leads to a linear dispersion of the tau(r). The two types of QW inhomogenities (QW width and indium concentration fluctuations) lead to a situation where the same emission wavelength can be realized by QWs with significantly different tau(r) constants. Such a behavior of the tau(r) leads to a non-exponential decay of photoluminescence.