Effects of symmetry of GaN-based two-dimensional photonic crystal with quasicrystal lattices on enhancement of surface light extraction

Abstract

We demonstrate enhancement of surface light extraction from two-dimensional photonic crystals (2D-PCs) on the electrical injected GaN-based light emitters. The effects of symmetry of PCs on light extraction were studied. 2.5 times enhancement of surface emission was obtained from the PCs with an octagonal symmetric quasicrystal lattice (8PQC) compared to that from a nonpatterned region. Additionally the surface emission from PCs with dodecagonal symmetric quasicrystal lattice (12PQC) exhibited about 1.7 and 1.4 times higher emission than regular PCs with triangular lattice and 8PQC, respectively. Consequently, the 12PQC provides a favorable consideration of 2D-PC in light extraction from light emitting diode.

Spatial mapping on surface light extraction from 2D photonic quasicrystals patterned GaN‐based light emitters

“…The 2D-PC patterns were located on the interspacing between the broad-stripe electrodes where the p-type metal films had been etched off. The detail structures of the devices were similar to the previous publications [8,9].…”

“…Photonic Quasicrystal (PQC) is a special kind of photonic crystals with quasiperiodic lattice arrays and shows more scattering properties and more easily achieved omni-directional band gap than conventional periodic photonic crystals [4,5]. Employing PQC on the surface of LED could also show emission enhancement [6][7][8]. In this work, we report the spatial mapping of enhanced surface light extraction from arrays of dodecagonal symmetric photonic quasicrystal (12PQC) on current injected GaN-based emitters.…”

Lattice-parameter effects on diffracted transmission of GaN two-dimensional square-lattice photonic crystals

“…However, the optimization of PhC is challenging since many parameters of PhC are involved and correlated to each other, such as lattice pitch, fill factor and etch depth. We notice a large variation in PhC lattice pitch employed by different groups in GaN-based blue LEDs corresponding to the Bragg diffraction conditions of the first order [4,5], second order [4] and even higher orders [6][7][8][9]15,17,18], respectively. In particular, David et al [5] thought that the highest extraction efficiency was achieved around the first Bragg diffraction.…”

“…Various approaches have been adopted to extract the light trapped in LEDs. A great number of efforts have been made to use photonic crystals to improve the light extraction or control the radiation pattern of various types of GaN-based LEDs, such as commercial LEDs with GaN on sapphire substrate [1][2][3][4][5][6][7][8][9][10][11][12], thin-film LEDs [4,[13][14][15], flip-chip LEDs [16] and micro-cavity LEDs [17]. Though the coupling between the photonic crystal and guided modes is different due to the different types of LEDs, the strategy of using a PhC grating in most publications mainly relies on Bragg diffraction of the trapped guided modes from the LEDs.…”

Improved Light Output Power of GaN-Based Light-Emitting Diodes Using Double Photonic Quasi-Crystal Patterns

“…We choose the 12-fold PQC pattern due to the better enhancement of surface emission. This is obtained from the photonic crystals (PCs) with a dodecagonal symmetric quasicrystal lattice, as opposed to regular PCs with triangular lattice and eightfold PQC [16]. The recursive tiling of offspring dodecagons packed with random ensembles of squares and triangles in dilated parent cells forms the lattice.…”