The use of self-assembled monolayers of silica microspheres was demonstrated as selective growth masks for significant threading dislocation density reduction in GaN on sapphire epilayers. During GaN re-growth through the close-packed monolayer, the silica microspheres effectively terminate the propagation of threading dislocations. As a result, the threading dislocation density, measured by large area atomic force microscopy and cathodoluminescence scans, was reduced from 3.3 x 109 to 4.0 x 107/cm2. This nearly two orders of magnitude reduction was attributed to dislocation blocking and bending by the unique interface between GaN and silica microspheres.

Dislocation Density Reduction in GaN by Dislocation Filtering through a Self-Assembled Monolayer of Silica Microspheres. Q.Li, J.J.Figiel, G.T.Wang: Applied Physics Letters, 2009, 94[23], 231105