Wang X H, Fu W Y, Lai P T, Choi H W
Semiconductor Display and Lighting Laboratory, Department of Electrical and Electronic Engineering The University of Hong Kong, Pokfulam Road, Hong Kong.
Opt Express. 2009 Dec 7;17(25):22311-9. doi: 10.1364/OE.17.022311.
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.
通过激光微加工制备了长方体和圆盘形的蓝色氮化镓发光二极管（LED）。所提出的圆形几何形状有助于在宏观尺度上提高整体光提取效率，并由于芯片的旋转对称性而改善发射图案的均匀性。通过光线追踪模拟对芯片成形效果进行分析，并使用理想LED模型进行数学建模进一步支持，随后用制造的器件进行验证。相比之下，圆形LED的整体发射比普通长方体LED提高了10%，与模拟和计算结果一致。从圆形LED测量的发射图案证实了发射光束的轴对称性。
