Polarity Control in 3D GaN Structures Grown by Selective Area MOVPE

During the metal organic vapor phase epitaxy of GaN microcolumns, both nitrogen- and gallium-polar GaN in the same structures could be detected on patterned SiO x /sapphire templates. To clarify its origin, the spatial distribution of surface polarity has been analyzed by both Kelvin probe force microscopy and selective etching techniques. A new “truncated pyramid + column” growth method was developed to effectively avoid the formation of mixed polarity and realize selective area growth of single N-polar GaN columns. The strong yellow luminescence in mixed polarity structures can substantially be eliminated in single N-polar core–shell light-emitting diodes.