Enhanced light extraction of GaN-based LEDs with various shape and geometric lattice photonic crystal structures

Photonic crystal structures with different shape air holes including triangles, squares, and circles were fabricated on top of blue GaN-based light emitting diodes using electron beam lithography and inductively coupled dry etching processes. Light extraction dependence of the patterned LEDs on shape and geometrical symmetry of two-dimensional photonic crystal structures was demonstrated. Cathodoluminescence studies reveal that the LED with a hexagonal lattice photonic crystal structure of the square air holes shows about 5-fold enhancement of luminescence intensity compared to sample without photonic crystal structure.