Effects of capping on GaN quantum dots deposited on Al0.5Ga0.5N by molecular beam epitaxy

Korytov, M.; Benaissa, M.; Brault, J.; Huault, T.; Neisius, T.; Vennéguès, P.
April 2009
Applied Physics Letters;4/6/2009, Vol. 94 Issue 14, p143105
Academic Journal
The impact of the capping process on the structural and morphological properties of GaN quantum dots (QDs) grown on fully relaxed Al0.5Ga0.5N templates was studied by transmission electron microscopy. A morphological transition between the surface QDs, which have a pyramidal shape, and the buried ones, which have a truncated pyramid shape, is evidenced. This shape evolution is accompanied by a volume change: buried QDs are bigger than surface ones. Furthermore a phase separation into Al0.5Ga0.5N barriers was observed in the close vicinity of buried QDs. As a result, the buried QDs were found to be connected with the nearest neighbors by thin Ga-rich zones, whereas Al-rich zones are situated above the QDs.


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