Increased effective reflection and transmission at the GaN-sapphire interface of LEDs grown on patterned sapphire substrates

• Published in: 半导体学报：英文版 2016, Vol.37 (10), p.60-64
• Main Author: 吴冬雪 马平 刘波亭 张烁 王军喜 李晋闽
• Format: Article
• Language: English
• Subjects: 倒装芯片; 反射; 发光二极管; 图案化; 生长; 界面层; 蓝宝石衬底; 透射
• ISSN: 1674-4926

The effect of patterned sapphire substrate（PSS） on the top-surface（P-Ga N-surface） and the bottomsurface（sapphire-surface） of the light output power（LOP） of Ga N-based LEDs was investigated, in order to study the changes in reflection and transmission of the Ga N-sapphire interface. Experimental research and computer simulations were combined to reveal a great enhancement in LOP from either the top or bottom surface of Ga N-based LEDs, which are prepared on patterned sapphire substrates（PSS-LEDs）. Furthermore, the results were compared to those of the conventional LEDs prepared on the planar sapphire substrates（CSS-LEDs）. A detailed theoretical analysis was also presented to further support the explanation for the increase in both the effective reflection and transmission of PSS-Ga N interface layers and to explain the causes of increased LOP values. Moreover, the bottom-surface of the PSS-LED chip shows slightly increased light output performance when compared to that of the top-surface. Therefore, the light extraction efficiency（LEE） can be further enhanced by integrating the method of PSS and flip-chip structure design.