Dislocation density reduction in GaN by dislocation filtering through a self-assembled monolayer of silica microspheres

We demonstrate the use of self-assembled monolayers of silica microspheres as selective growth masks for significant threading dislocation density reduction in GaN on sapphire epilayers. During GaN regrowth 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, is reduced from 3.3×109 to 4.0×107 cm−2. This nearly two orders of magnitude reduction is attributed to dislocation blocking and bending by the unique interface between GaN and silica microspheres.