图形化蓝宝石衬底形貌对GaN基LED出光性能的影响

近年来,图形化蓝宝石衬底(PSS)作为GaN基LED外延衬底材料被广泛应用.通过干法刻蚀和湿法腐蚀制备了不同规格和形状的蓝宝石衬底图形,并进行外延生长、芯片制备和封装验证,采用扫描电子显微镜(SEM)和3D轮廓仪进行形貌表征,研究了不同规格和形状的衬底图形对LED芯片出光性能影响,并与外购锥形衬底(PSSZ2)进行对比.结果表明,在20 mA工作电流下,PSSZ2的LED光通量为8.33 lm.采用类三角锥和盾形衬底的LED光通量分别为7.83 lm和7.67 lm,分别比PSSZ2衬底低6.00％和7.92％.对锥形形貌进行优化,采用高1.69 μm、直径2.62 μm、间距0.42 μm的锥形衬底(PSSZ3)的LED光通量为8.67 lm,比PSSZ2衬底高4.08％,优化的PSSZ3能有效地提高LED出光性能.

Influences of Patterned Sapphire Substrate Morphology on the GaN-Based LED Luminescence Properties

In recent years,the patterned sapphire substrate (PSS) has been widely applied as the epitaxial substrate material for the GaN-based LED.Sapphire substrate patterns in different sizes and shapes were prepared by dry etching and wet etching and the epitaxial growth,chip fabrication and packaging verification were completed on different samples.The morphology of the PSS was characterized by using the scanning electron microscope (SEM) and 3D profiler,respectively.The effects of substrates with different sizes and patterns on the luminous properties of LED chips were studied,and compared with purchased conical substrates (PSSZ2).The results show that the luminous flux of the LED with the PSSZ2 substrates is 8.33 lm at the 20 mA operating current.The luminous flux of the LED with triangular cone and shield substrates are 7.83 lm and 7.67 lm,which is 6.00％ and 7.92％ lower than that of the PSSZ2 substrate,respectively.The conical surface morphology was optimized by using the conical substrate (PSSZ3) with the height,diameter and distance of 1.69,2.62 and 0.42 μm,respectively.The luminous flux of the LED with the PSSZ3 substrate is 8.67 lm,which is 4.08％ higher than that of the PSSZ2 substrate.The optimized PSSZ3 substrate can effectivly improve the luminescence properties of LED.