GaN基垂直结构LED的n型电极结构设计及芯片制备

首先利用电流路径模型分析n型电极尺寸及间距等对垂直结构发光二极管(VS-LEDs)电流分布均匀性的影响,依此设计出一种螺旋状环形结构电极。其次,通过建立有限元分析软件Comsol仿真模型模拟VSLEDs有源层的电流密度分布,发现螺旋状环形结构电极的环间距越小,电流密度分布越均匀。最后,利用VS-LEDs芯片制备技术实现具有螺旋状环形电极的垂直结构LED芯片。实验结果显示,在350 m A电流驱动下,电极环间距为146.25μm的芯片具有最大的功能转换效率,达到26.8%。

n-type Electrode Patterns Design and Device Fabrication of GaN-based Vertical Structure LEDs

The influences of size and spacing of n-type electrode on the current distribution of verti-cal-structure light-emitting diodes ( VS-LEDs) were firstly analyzed by two-dimension circuit model-ing, and annulospiral n-type electrodes were proposed for the fabrication of VS-LEDs. Then, finite element analysis model in Comsol Multiphysics was built to study the current density distribution in the active layer of VS-LEDs with the annulospiral electrodes. It is found that the current density dis-tribution became more uniform when the electrode spacing reduced. Finally, VS-LEDs with various annulospiral electrodes were fabricated using high-reflectivity p-type Ohmic electrode, copper sub-strate electroplating and laser lift-off techniques. The wall plug efficiency of VS-LEDs with the elec-trode spacing of 146. 25 μm is 26. 8% at 350 mA, which is higher than that of VS-LEDs with other electrode spacings.