激光剥离转移衬底的薄膜GaN基LED器件特性分析  

Thin Film GaN-Based LEDs on Cu Substrates Fabricated by Laser Lift-Off

作　　者：孙永健[1] 陈志忠[1] 齐胜利[1] 于彤军[1] 康香宁[1] 刘鹏[1] 张国义[1] 朱广敏 潘尧波 陈诚 李仕涛 颜建峰 郝茂盛 

机构地区：[1]北京大学物理学院介观物理实验室,北京100871 [2]上海蓝光科技有限公司,上海200120

出　　处：《半导体技术》2008年第S1期219-223,共5页Semiconductor Technology

基　　金：国家自然科学基金(60676032;60406007;60607003;60577030);国家"973"重点基础研究项目(TG2007CB307004)

摘　　要：制备了基于蓝宝石衬底的GaN基LED(C-LED)以及由激光剥离技术(LLO)制作的基于Cu衬底的相同电学结构的薄膜GaN基LED(LLO-LED)。通过研究发现,经过激光剥离过程后,器件的反向漏电流明显增加,其等效并联电阻下降了近两个数量级。通过对变温I-V曲线的分析,反向偏压下隧穿漏电机制的主导地位被发现并证实,而激光剥离前后样品腐蚀后的AFM照片显示缺陷密度没有明显改变。隧穿机制的增加是由于激光剥离过程激发了更多缺陷的隧穿活性。然而,蓝宝石衬底LED以及激光剥离薄膜Cu衬底LED的相似的理想因子和等效串联电阻说明激光剥离过程并未对器件的正向电学特性造成大的伤害。因此,高质量、高功率的激光剥离LED器件是可以期待的。对L-I曲线的分析显示,激光剥离过程引入了更多的非辐射复合中心,但激光剥离薄膜Cu衬底LED器件在大电流注入下仍然有着超出常规器件的表现。在300mA注入电流内,激光剥离薄膜Cu衬底LED展示的最大光功率是蓝宝石衬底GaN基LED的1.8倍,饱和电流超过2.5倍。这些结果显示,激光剥离Cu衬底LED仍然是高功率高亮LED的首选方案。The conventional GaN-based light-emitting diodes(LEDs)on sapphire substrates and laser lift-off(LLO)lateral current structure GaN LED thin film chips on Cu substrates were fabricated.The study results show that after the LLO process,the reverse bias leakage current obviously increases and equivalent parallel resistance decreases 2 orders accordingly.From analysis of I-V curves the fact that tunneling behavior dominates under the reverse bias is confirmed.The AFM image of the conventional LEDs and LLO LEDs after etched reveals that the defect density has no obviously changes after the LLO process.Thereby,the increase of tunneling current should caused by the increase of the defects' tunneling activity after the LLO process.Whereas the similar ideality factors and equivalent series resistance of the LLO-LEDs on Cu and the conventional LEDs on sapphire suggest that the LLO process does not much damage the electrical characteristics at forward bias.The analysis of L-I curves reveals that the LLO process induces more nonirradiation centers.However,the LLO-LEDs show superior performance under large injection current.The LLO-LEDs have 1.8 times greater maximum output power and 2.5 higher current operation capabilities than the conventional LEDs within 300 mA for the good thermal conductivity of Cu.

关 键 词：氮化镓 发光二极管 激光剥离 漏电流 

分 类 号：TN304[电子电信—物理电子学]