Threading dislocation reduction in epitaxial GaN using V-groove patterned sapphire substrate with embedded silica nanospheres

• Silica nanosphere was used in reduction of threading dislocation and stress-relaxation in GaN epilayer.
• V-groove patterned sapphire substrate (VGSS) with the silica nanosphere double-fit embedded (SNDE) structure is considered in the growth of GaN.
• The generation of edge or mixed threading dislocations are terminated at the regrown GaN epilayer in TEM images.

A dramatic reduction in threading dislocation density and stress-relaxation was simultaneously achieved in GaN epilayer using a silica nanosphere embedded structure on V-groove patterned sapphire substrate by metal-organic chemical vapor deposition. By depositing silica nanospheres at two different instances during a growth process, a two-step growth that included selective area growth and lateral overgrowth was initiated. This approach led to GaN template of high crystal quality, which was confirmed from x-ray diffraction rocking curve and micro-Raman measurements and further corroborated by transmission electron microscopy. GaN light-emitting diode fabricated by this strategy showed a significant enhancement in the light output power.