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GaN基LED的电流横向扩展导致电流分布不均匀的现象仍是目前亟待解决的难题,对于高压倒装LED更是如此。传统的LED工艺把负电极直接制作在n-GaN材料表面,而提出的优化结构是负电极内嵌于n-GaN材料。首先通过LED电流扩展的简单建模来探讨器件内部的电流分布情况,得出优化结构有利于改善芯片内部电流分布的理论推导。再进一步用SILVACO软件对优化结构和传统结构芯片内部电流分布进行了仿真对比,结果表明前者电流密度仅为后者的55%。最后制作了相关LED芯片样品进行热阻测试对比,实验表明优化结构芯片的结温和热阻较传统结构分别下降了13%和26%。可见芯片结构的优化设计方案是有效可行的。
GaN-based LED current lateral expansion leads to uneven current distribution is still the problem to be solved, especially for high-voltage flip-LED. The traditional LED process makes the negative electrode directly on the surface of n-GaN material, and the optimized structure is that the negative electrode is embedded in the n-GaN material. Firstly, the current distribution inside the device was explored by the simple modeling of LED current expansion, and the theoretical derivation of optimizing the structure to improve the current distribution inside the chip was obtained. The simulation results show that the current density of the former is only 55% of that of the latter with SILVACO software. The LED chip samples were finally fabricated for thermal resistance comparison. The experimental results show that the junction temperature and the thermal resistance of the optimized structure chip are reduced by 13% and 26% respectively compared with the traditional structure. Visible chip structure optimization design is effective and feasible.