Optimization of lattice constants of 2D photonic crystals fabricated on ITO layers of LEDs using holographic method for efficient light extraction
- 物理技术－会议论文 
Fabricating 2-dimensional (2D) photonic crystals (PCs) on InSnO2 (ITO) layers of LEDs can largely enhance light extraction efficiency. The paper presents the theoretical analysis for determining the optimal lattice constants for PC-LEDs to acquire more efficient light extraction. The equations for obtaining optimal hexagonal lattice constants corresponding to different LED wavelengths were derived. Calculation shows that for 450 nm GaN-LEDs, the optimal lattice constant is about 500 nm, and for the lattice constants in the range from a few micron to 500 nm, light extraction increases with the reduction of lattice constant. In the experiment, hexagonal PCs with 1.8 micron, 1.5micron and 1.2 micron lattice constants were fabricated in ITO layers of GaN-LEDs using holographic 3-beam interference approach and wet etching, resulting in 6%, 12% and 22.5% output increase respectively under 20 mA current injection. The experimental result demonstrates that higher light extraction is acquired with the lattice constants closer to the optimum, which is consistent with the theoretical analysis.