Large-scale SiO sub(2) photonic crystal for high efficiency GaN LEDs by nanospherical-lens lithography

• Published in: Chinese physics B Vol. 23; no. 2; pp. 028504 - 1-028504-4
• Main Authors: Wu, Kui, Wei, Tong-Bo, Lan, Ding, Zheng, Hai-Yang, Wang, Jun-Xi, Luo, Yi, Li, Jin-Min
• Format: Journal Article
• Language: English
• Published: 01.02.2014
• Subjects: Electric power generation; Etching; Indium tin oxide; Light-emitting diodes; Lithography; Nanostructure; Photonic crystals; Silicon dioxide
• ISSN: 1674-1056; 1741-4199
• DOI: 10.1088/1674-1056/23/2/028504

Wafer-scale SiO sub(2) photonic crystal (PhC) patterns (SiO sub(2) air-hole PhC, SiO sub(2)-pillar PhC) on indium tin oxide (ITO) layer of GaN-based light-emitting diode (LED) are fabricated via novel nanospherical-lens lithography. Nanoscale polystyrene spheres are self-assembled into a hexagonal closed-packed monolayer array acting as convex lens for exposure using conventional lithography instrument. The light output power is enhanced by as great as 40.5% and 61% over those of as-grown LEDs, for SiO sub(2)-hole PhC and SiO sub(2)-pillar PhC LEDs, respectively. No degradation to LED electrical properties is found due to the fact that SiO sub(2) PhC structures are fabricated on ITO current spreading electrode. For SiO sub(2)-pillar PhC LEDs, which have the largest light output power in all LEDs, no dry etching, which would introduce etching damage, was involved. Our method is demonstrated to be a simple, low cost, and high-yield technique for fabricating the PhC LEDs. Furthermore, the finite difference time domain simulation is also performed to further reveal the emission characteristics of LEDs with PhC structures.