具有表面周期性微结构的LED垂直结构功率芯片制备

发布时间：2018-04-17 20:42

  本文选题：垂直结构LED芯片 + 出光效率　； 参考：《华南理工大学》2016年硕士论文

【摘要】：GaN基垂直结构LED芯片相对传统结构LED芯片具有出光面积大,散热性能好,电流扩展均匀等优点,更加适用于大功率固态照明光源,是LED照明发展的一个重要方向。然而垂直结构LED芯片的制备工艺更加复杂,本文在完善垂直结构LED芯片制备工艺的同时,对垂直结构LED芯片的结构进行设计,对芯片出光面N极性的氮化镓层表面结构进行研究,对垂直结构LED芯片的表面n型电极结构进行优化,最终获得高效大功率的垂直结构LED芯片。针对光在空气/n-GaN界面处的菲涅尔反射、全反射引起光子损耗,从而限制垂直结构LED芯片出光效率的问题,利用N极性面Ga N出光面易被KOH溶液刻蚀而改变表面结构的特点,以KOH溶液为刻蚀液,分别对普通表面GaN基垂直结构LED芯片和具有表面周期性微结构的芯片进行N极性面GaN的表面结构优化研究。在刻蚀普通表面N极性面GaN的过程中,当刻蚀浓度为6mol/L,刻蚀温度为80℃,刻蚀时间为8min时,样品光输出功率与参考样品相比提升了175%@100mA;而在具有表面周期性微结构的N极性面GaN表面结构刻蚀优化过程中,采用刻蚀溶液的浓度为2mol/L,温度为95℃,刻蚀的时间为6min的条件获得了较优的刻蚀效果,此时样品光输出功率与参考样品相比高出23.08%@100mA。针对大电流注入下电流易在n电极下方集聚的问题,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LED芯片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。通过建立有限元分析软件COMSOL Multiphysics仿真模型模拟垂直结构LED芯片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。利用垂直结构LED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350mA电流注入下,当电极环间距为146.25μm时的芯片具有最大的功能转换效率,达到26.8%。
[Abstract]:Compared with the traditional LED chip, GaN based vertical structure LED chip has many advantages, such as large light area, good heat dissipation, uniform current spread and so on. It is more suitable for high power solid-state lighting source. It is an important direction in the development of LED lighting.However, the fabrication process of vertical structure LED chip is more complicated. In this paper, the structure of vertical structure LED chip is designed while perfecting the fabrication process of vertical structure LED chip.The surface structure of gallium nitride layer with N polarity is studied, and the surface n-type electrode structure of vertical structure LED chip is optimized. Finally, a high efficiency and high power vertical structure LED chip is obtained.Aiming at the Fresnel reflection of light at the air / n-GaN interface, the total reflection causes photon loss, which limits the optical efficiency of the vertical structure LED chip. The characteristic of changing the surface structure by using the N polarity surface Ga N luminous surface is easy to be etched by KOH solution.Using KOH solution as etching solution, the surface structure optimization of normal surface GaN based LED chips and chips with periodic surface microstructures was studied respectively.When the etching concentration is 6 mol / L, the etching temperature is 80 鈩，

本文编号：1765217