Two-dimensional photonic quasicrystal on the surface of GaN-based light emitting diodes

Two-dimensional (2D) photonic crystal (PhC) patterns in regular four-fold symmetry (2PhC) and dodecagonal symmetric photonic quasicrystal (12PQC) with 970 nm lattice pitch have been formed by electron beam lithography on the surface of GaN-based light emitting diodes (LEDs). The symmetry of a 2D quasicrystal in this work was based on a square-triangle tiling system. The enhancement of light extraction was obtained from both the 2PhC and 12PQC introduced GaN-based LEDs, and 12PQC is favourable compared to 2PhC. To explore the physical properties, we proposed a method for inspecting diffraction behaviours of the PhC arrays. The results supplied a clear representation of the diffraction behaviours of 2PhC and 12PQC that correspond to their lattice symmetry.