Effect of Electrode Pattern on Light Emission Distribution in InGaN/GaN Light Emitting Diode

The effect of geometrical electrode pattern on the blue In-GaN/GaN multi-quantum well (MQW) light emitting diode (LED) devices is investigated both theoretically and experimentally. A 3-dimensional circuit model of an LED is constructed and then the corresponding circuit parameters are extracted. Circuit parameters of an LED consist of the resistances of the metallic film and epitaxial layer, and intrinsic diodes representing the light-emitting active region. Both the transmission line model (TLM) and current-voltage (I-V) characteristics of LED are employed to extract circuit parameters experimentally. These circuit parameters are then applied to the circuit model to generate light emission patterns in a top-surface emitting-type LED. Experiment results verify that the emitting light distribution from fabricated LED coincides reasonably well with the theoretical results. This makes it possible to design an LED theoretically and predict its actual properties. The LED structure proposed using the model is shown to exhibit not only good light uniformity, but also higher light output power and lower voltage drop. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA