Nanoscale cathodoluminescence spectroscopy probing the nitride quantum wells in an electron microscope

To gain further understanding of the luminescence properties of multiquantum wells and the factors affecting them on a microscopic level, cathodoluminescence combined with scanning transmission electron microscopy and spectroscopy was used to measure the luminescence of In_0.15Ga_0.85N five-period multiquantum wells. The lattice–composition–energy relationship was established with the help of energy-dispersive x-ray spectroscopy, and the bandgaps of In_0.15Ga_0.85N and GaN in multiple quantum wells were extracted by electron energy loss spectroscopy to understand the features of cathodoluminescence spectra. The luminescence differences between different periods of multiquantum wells and the effects of defects such as composition fluctuation and dislocations on the luminescence of multiple quantum wells were revealed. Our study establishing the direct relationship between the atomic structure of In_xGa_1−xN multiquantum wells and photoelectric properties provides useful information for nitride applications.