| 초록 |
The nonuniform current flow pattern in a light emitting diode (LED) results in serious problems such as a local heat generation, an early saturation of light emission power, an unexpected light emission pattern, color binning, and a short device lifetime. We present a theoretical method of analyzing 3-dimensional current flow in a complex light emitting diode (LED) structure. The method is based on 3-dimensional circuit modeling and its analysis so that it has advantages of short calculation time and simple algorithm over the method of solving semiconductor differential equations. Our software is able to know how to influence structural parameters such as epitaxial layers, electrode pattern, and chip shape on the current crowding without fabricating LEDs. Its accuracy is confirmed experimentally by investigating 2-dimensional light intensity patterns on lateral-electrode (LE) InGaN/GaN blue LEDs of 320x320 µm2 size. By utilizing the software, we designed and fabricated several different n-electrode patterns on the same epitaxial wafer and investigated the relation between nonuniform current flowing patterns with LED performances. It was found that the nonuniform current flow significantly affected the electrical and optical characteristics, electrostatic discharge voltage, and LED lifetime. Based on these experimental results, we successfully designed some electrode patterns giving high performances in LE-LEDs of the rectangular and the lozenge shapes. |
