N-GaN column arrays on the vertical InGaN/GaN blue LEDs formed by maskless dry etching

摘要

The InGaN/GaN blue light emitting diodes (LED) structures have been grown on sapphire substrates with a hexagonal array of hemispherical patterns by low-pressure metalorganic chemical vapor deposition. Vertical LED structures on Cu carriers are fabricated using electroplating and KrF laser lift-off techniques. After removal of the patterned sapphire substrate, an inductively coupled plasma etching is carried out to expose the n-GaN layer for n-metal contact. It is observed that GaN columns are formed at the center of the concave hemispheres after dry etching processes. Cathodoluminescence and wet chemical etching investigations reveal that a high density of dislocations is found to be generated at these specific positions. The possible mechanism for these observations is attributed to the defect distribution and defect-dependent selective etching of the GaN.