The use of self-assembled monolayers of silica microspheres as selective growth

masks for significant threading dislocation density reduction in GaN on sapphire

epilayers was demonstrated. During GaN regrowth through the close-packed

monolayer, the silica microspheres effectively terminated 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 almost two orders of magnitude reduction

was attributed to dislocation blocking and bending by the unique interface between

GaN and the 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