title: Evaluation of InGaN/GaN light-emitting diodes of circular geometry.
abstract: Blue GaN light emitting diodes (LEDs) in the shape of cuboids and circular disks have been fabricated by laser micromachining. The proposed circular geometry serves to enhance overall light extraction on a macro-scale and to improve uniformity of the emission pattern due to the rotational symmetry of the chip. Analysis of the chip shaping effect is carried out by ray-tracing simulations and further supported with mathematical modeling using ideal LED models, and subsequently verified with fabricated devices. In comparison, a 10% improvement in overall emission was observed for circular LEDs over the regular cuboids, consistent with simulations and calculations. The measured emission pattern from the circular LED confirms the axial symmetry of the emission beam.
authors.affiliation: Semiconductor Display and Lighting Laboratory, Department of Electrical and Electronic Engineering The University of Hong Kong, Pokfulam Road, Hong Kong.
authors.forename: X H
authors.initials: XH
authors.lastname: Wang
authors.forename: W Y
authors.initials: WY
authors.lastname: Fu
authors.forename: P T
authors.initials: PT
authors.lastname: Lai
authors.forename: H W
authors.initials: HW
authors.lastname: Choi
mesh_terms: D003198:Computer Simulation; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005708:Gallium / Q000737:chemistry*; D007204:Indium / Q000737:chemistry*; D008029:Lighting / Q000295:instrumentation*; D008956:Models, Chemical; D012666:Semiconductors
chemical_list: D007204:Indium; C473348:gallium nitride; D005708:Gallium; C513701:indium nitride