Research on vertical-type deep UV LEDs using new-concept substrate lift-off techniques

该项目的重点是通过去除基板来开发垂直结构的深紫外光LED。在传统的蓝光LED衬底去除技术中，激光剥离是用来去除衬底和GaN外延层之间界面处的衬底。对于深紫外光LED，激光剥离设备应该进行修改，以适应AlN层以下界面的移除。通过改善AlN层的结晶质量以及发展用于激光剥离的异质结构，已经实现了超过几mW的发射。此外，还使用了硅衬底作为试验衬底。改善了晶体质量和裂纹形成，证明了湿法刻蚀去除硅衬底的可行性。

This project focused on development of vertically-constructed deep UV LEDs by removing substrates. In the conventional substrate-removing techniques for blue LEDs, laser-lift off is used to remove substrates at the interfaces between substrate and GaN epi-layers. For deep UV LEDs, laser-lift off equipment should be modified to fit to remove at the interface below AlN layers. By improvement of crystalline quality of AlN layers as well as development of hetero-structures for laser-lift off, over several mW emission has been achieved. In addition, Si substrates were used as substrates on trial. Crystalline quality and crack formation were improved, and removing Si substrates by wet etching was demonstrated.