GaN-based light emitting diodes are extensively used for light emitting' diodes in the green to ultraviolet (UV) wavelength region and have already been widely used in traffic signals, outdoor displays, full-color displays and back lighting in liquid-crystal displays. Although GaN-based light emitting diodes are commercially available, it is still difficult to manufacture highly efficient GaN-based light emitting diodes due to the high dislocation density and the low light extraction efficiency. Patterned sapphire substrates for GaN-based light-emitting diodes have attracted much interest in recent years because it can not only reduce the threading dislocation density of epitaxial GaN films, but also improve the light extraction efficiency of GaN-based light-emitting diodes. A comprehensive review is presented on the mechanisms responding for performance enhancement of GaN-based light emitting diodes on patterned sapphire substrates, methods of preparing patterned sapphire substrates and pattern-size of patterned sapphire substrates. What is more, improved performance of GaN-based light-emitting diodes on patterned sapphire substrates prepared by different methods and pattern-size are further discussed in detail. In view of the existing problems, the prospects for future development of patterned sapphire substrates are also proposed.%近几年,图形化蓝宝石衬底因其作为GaN基发光二极管外延衬底,不仅能降低GaN外延薄膜的线位错密度,还能提高LED的光提取效率而引起国内外许多科研机构的广泛研究兴趣.本文综述了图形化蓝宝石衬底提高GaN基发光二极管性能的作用机理,重点评述了目前图形化蓝宝石衬底的制备方法(湿法刻蚀、干法刻蚀、固相反应)和图形尺寸(微米图形化、纳米图形化),分析比较了不同制备方法和图形尺寸制备蓝宝石图形衬底对GaN基发光二极管性能改善,最后针对蓝宝石图形衬底制备存在的问题对其今后的发展方向做出了展望.
展开▼
