Transmission electron microscopic observations were made of erratic dislocation behaviour within funnel-like defects on top of AlN templates filled with AlGaN from an overlying epitaxial layer. This dislocation behaviour was observed in material where phase separation was also observed. Several bare AlN templates were examined to determine the formation mechanism of the funnels. The results suggested that they were formed prior to epitaxial layer deposition due to the presence of impurities during template re-growth. The erratic dislocation behaviour was considered with regard to the presence of the phase-separated material and the possible effects of these defects upon opto-electronic properties.

Erratic Dislocations within Funnel Defects in AlN Templates for AlGaN Epitaxial Layer Growth. M.E.Hawkridge, Z.Liliental-Weber, H.J.Kim, S.Choi, D.Yoo, J.H.Ryou, R.D.Dupuis: Applied Physics Letters, 2009, 94[17], 171912