设计了用于发光二极管(LED) 微显示器折射率匹配层结构, 可以提高LED 微显示器的光学性能。倒装结构的LED微显示器出光面为蓝宝石(折射率约1.76), 它和空气的折射率(约为1.0)相差较大, 会有很大一部分光因为全反射而反射回器件内部被吸收, 导致器件的光效率降低。本文通过涂敷折射率匹配层硅胶(折射率约1.41～1.53)的方法, 改变器件表层的折射率使其和空气的折射率相匹配, 增加光逃逸锥角, 从而提高器件的光效率。结果表明涂敷硅胶可以提高光效率约25.75%, 在涂敷硅胶基础上盖玻璃片(折射率约1.47)可提高光效率约32.78%, 且硅胶涂敷前后器件的电学、光学、结温稳定性好。尽管增加的是侧方向的光通量, 但是其光效率的增加为高效率LED微显示的实现提供了参考依据。

The structure based on a refractive index matching layer on light emitting diode (LED) microdisplay is designed to improve its optical performance. The light-emitting surface of the flip-chip LED microdisplay device is a sapphire (refractive index about 1.76), which is significantly different from the refractive index of air (refractive index about 1.0). A large part of the light is reflected back to the internal of the device due to total reflection, resulting in low luminous efficiency. By coating a refractive index matching layer of silica gel (refractive indexes about 1.41～1.53), the surface layer of the device is changed to match the refractive index of the air to increase the light escape cone angle to improve the luminous efficiency of the device. The results show that: the application of the silica gel layer can improve the luminous efficiency by about 25.75%, and then covering a glass (refractive index about 1.47) on the silica gel layer can improve the luminous efficiency to about 32.78%, and the device has good electrical, optical and junction temperature stability before and after silicone coating. Although the increased light flux is in the lateral direction, this technique provides a reference for a realization of high-efficiency LED microdisplay.