Structural Modifications in Free-Standing InGaN/GaN LEDs after Femtosecond Laser Lift-Off
Structural Modifications in Free-Standing InGaN/GaN LEDs after Femtosecond Laser Lift-Off
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DOI：
10.3390/proceedings2130897
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发表时间：
2018-11
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影响因子：
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通讯作者：
S. Bornemann;N. Yulianto;T. Meyer;Jan Gülink;C. Margenfeld;M. Seibt;H. S. Wasisto;A. Waag
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文献类型：
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作者：
S. Bornemann;N. Yulianto;T. Meyer;Jan Gülink;C. Margenfeld;M. Seibt;H. S. Wasisto;A. Waag
发展了一种激光剥离(LLO)工艺，利用超快激光将InGaN/GaN发光二极管(LED)从原来的蓝宝石衬底上分离出来。LIO通常基于强烈的紫外光照射，紫外光透过蓝宝石衬底，然后在外延生长的GaN堆栈的界面处被吸收。在这里，我们介绍了一种基于双光子吸收机制的两步LLO过程的成功实现，该过程在绿色光谱范围(520 Nm)内获得了350飞秒的短脉冲。阴极和电致发光实验证明了LLO芯片的功能。用扫描电子显微镜和透射电子显微镜分析了辐照对材料质量的影响，揭示了某些情况下GaN层内部的结构变化。
A laser lift-off (LLO) process has been developed for detaching thin InGaN/GaN lightemitting diodes (LED) from their original sapphire substrates by applying an ultrafast laser. LLO is usually based on intense UV irradiation, which is transmitted through the sapphire substrate and subsequently absorbed at the interface to the epitaxially grown GaN stack. Here, we present a successful implementation of a two-step LLO process with 350 fs short pulses in the green spectral range (520 nm) based on a two-photon absorption mechanism. Cathodo- and electroluminescence experiments have proven the functionality of the LLO-based chips. The impact of radiation on the material quality was analysed with scanning (SEM) and transmission electron microscopy (TEM), revealing structural modifications inside the GaN layer in some cases.