Cathodoluminescence nano-characterization of individual GaN/AlN quantum disks embedded in nanowires

AlN/GaN/AlN quantum disks (Q-disks) embedded in self-assembled hexagonally shaped GaN nanowires have been grown on the Si (111) substrate by plasma-assisted molecular beam epitaxy. To correlate the structural and optical properties of individual Q-disks inside the nanowire, highly spatially resolved cathodoluminescence (CL) spectroscopy in a scanning transmission electron microscope has been performed at 18K. CL spectrum linescans along a single nanowire clearly identify the emission from the GaN base around 354nm as well as two recombination channels at 347nm and 330nm directly correlated with the AlN/GaN/AlN Q-disk. A detailed characterization of these individual quantum objects is presented.