图形化蓝宝石衬底GaN基LED的研究进展

蓝宝石衬底作为发光二极管最常用的衬底,经过不断发展,在克服其与GaN间晶格失配和热膨胀失配问题上,研究人员不断提出解决方案。近期发展起来的图形化衬底技术,除了能减少生长在蓝宝石衬底上GaN之间的差排缺陷,提高磊晶质量以解决失配问题,更能提高LED的出光效率。从衬底图形的形状、尺寸、制备工艺出发,回顾了图形化蓝宝石衬底GaN基LED的研究进展,详细介绍了近年来关于图形化衬底技术与其他技术在提高LED性能方面的结合,总结了图形化蓝宝石衬底应用于大尺寸芯片的优势,并对其未来在大功率照明市场的应用进行了展望。

Research progress of Patterned Sapphire Substrate for GaN-Based Light-Emitting Diodes

Nowadays,the patterned sapphire substrate technology is used as a fundamental technology to overcome the material stress that the results from a combination of lattice mismatch and thermal expansion coefficient mismatch,and achieves high efficiency light emitting diodes(LED).This article briefly reviews recent development of patterned sapphire substrate for GaN-based LEDs.It starts with an introduction to the epitaxial growth of GaN on sapphire substrate and a number of new technologies to create LEDs with enhanced performance.The influences of uniformed shaped pattern,nano sized pattern and the pattern fabricating method,i.e.dry-or wet-etching methods on the light extraction efficiency of LEDs are presented.It is demonstrated that a combination of patterned substrate with other technologies is able to improve the performance of LEDs.The future directions in this area,like the possibility of appliance to large-size chips,design and optimization of nano-scale patterns,as well as to combine optical simulations,are mentioned.