Dislocation density in AlN grown on multistacked GaN/AlN quantum dot layers by molecular beam epitaxy

Abstract

AbstractThe influence of GaN/AlN quantum dots (QDs) on crystalline quality of AlN grown on multistacked QD layers was studied as a function of the GaN deposition. Dislocations in the AlN grown on the QD layers were bent by the existence of the QD layers and the dislocation density in the AlN was one order of magnitude smaller than that in AlN grown on sapphire substrate. In the measurement of Raman spectra, AlN E2 frequency and GaN A1 (LO) frequency depended on the deposition of GaN. The dependence of these two frequencies was strongly correlated. This suggests that the crystalline quality of AlN is affected by the growth condition of the GaN QDs and size distribution of QDs was of great importance in reduction of the dislocation density in AlN by using the QD layers as a buffer layer. The reduction of dislocation in the AlN is efficient when the small QDs are grown uniformly but inefficient when the large QDs are grown. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)