Phase separation in GaN/AlGaN quantum dots

Benaissa, M.; Gu, L.; Korytov, M.; Huault, T.; van Aken, P. A.; Brault, J.; Vennéguès, P.
October 2009
Applied Physics Letters;10/5/2009, Vol. 95 Issue 14, p141901
Academic Journal
Local investigations using high-angle annular-dark-field imaging combined with electron low-energy-loss spectroscopy were performed to closely characterize the GaN/Al0.5Ga0.5N quantum dots heterostructure. It is found that the Al0.5Ga0.5N barrier tends to exhibit phase separation. Gallium-rich arms arise from the top rims of the truncated quantum dots while the space between these arms is filled with aluminum-rich AlGaN. This phase separation, due to morphological and strain nonuniformities of the GaN front surface, provokes an optical-property modulation in the neighborhood of the quantum dots which, from a practical point of view, could affect the electronic barrier homogeneity.


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