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Typical atomic force microscopy images of (a) a thick layer grown on a -plane sapphire substrate and (b) GaN quantum dots formed on the layer surface after a growth interruption without ammonia.
Low temperature photoluminescence spectrum of GaN quantum dots grown on (nominal GaN ML). In the inset, the photoluminescence at and room temperature has been reported for comparison. Note that the differences in the spectrum shape and the slight shift in the quantum dots emission energy between the main figure and the inset are attributed to the difference in the laser excitation power densities and wavelengths (i.e., at and at , respectively).
Room temperature photoluminescence spectra of quantum dots as a function of the nominal thickness of GaN (from 8 to 16 ML). The samples were excited by an unfocused HeCd laser . The dotted line is a guide for the eyes.
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