在本篇論文中，我們利用次微米灰階週期性光柵結構和發光二極體 (light-emitting diodes LED) 整合，在發光二極體表面製作出次微米的週期性氮化矽膜灰階結構，近似陣列式的微光學元件，並且能夠對發光二極體的光型做調制。從分析與模擬的結果得知，利用此週期性結構可控制發光二極體的出光特性，由光型分析看出，我們能使LED出光集中在 ±30°的範圍，亦可使LED在±60° 的範圍均勻出光，因此，我們所提出的次微米灰階光柵結構，可有效的調制LED光型。
我們製作結構尺度為次微米光柵，其週期為500 nm，線寬為200 nm，是利用電漿蝕刻等乾式蝕刻法製作出來，不需遷就晶體本身的晶格面，因此，經由設計蝕刻參數可使光柵的形狀做改變，並且可在次波長的尺度下製作出灰階的結構，能拓展灰階結構的應用面。由於灰階週期性光柵本身具有折射率漸變的性質，利用此特性，在微光學元件中，原本需要在結構上方或下方鍍上匹配膜層來修整頻譜，現在僅需利用灰階光柵即可達到類似效果，這對未來次微米結構的整合與設計亦具有更高的自由度與便利性。

In our study, we modulate far-field patterns of LED by using silicon nitride micro structures. We use gray level structures as sub-micro optical elements array, and analyze the far-field patterns of LED modulated by silicon nitride sub-micro structures. From our analysis，we can concentrate far-field pattern intensity above 0.8 in ±30° or spread far-field pattern intensity uniformly above 0.8 in ±60° of LED.
The purpose of structures is a micron scale, which period is 500 nm and the structures is 200 nm. The structures are etched by Inductively-Coupled-Plasma-Etching System. In our study, the purposed sub-micro silicon nitride gray-level grating can be realized. For the far-field patterns modulation of LED, the sub-micro structures can be integrated in array and fabricated on LED to extend the application of LED optical system.

【1】 T. Fujii , Y. Gao , R. Sharma , E. L. Hu , S. P. DenBaars , and
S. Nakamura “ Increase in the extraction efficiency of GaN-based light-emitting diodes via surface roughening ” Appl. Phys. Lett., Vol. 84, No. 6 ( 2004 )
【2】 Cathleen Rooman , Maarten Kuijk , Roger Vounckx , Paul Heremans “ Reflective-refractive microlens for efficient lightemitting-
diode-to-fiber coupling” Optical Engineering 44(9) , 095005 ( 2005 )
【3】 H. W. Choi, C. Liu, E. Gu , G. McConnell , J. M. Girkin, I. M. Watson, and M. D. Dawson “ GaN micro-light-emitting diode arrays with monolithically integrated sapphire microlenses ” Appl. Phys. Lett., Vol. 84, No. 13, ( 2004 )
【4】 J. J. Wierer , M. R. Kramesa , J. E. Eplera , N. F. Gardnera , J. R. Wendtb , M. M. Sigalasc , S. R. J. Brueckd , D. Lid , and M. Shagame “III-Nitride LEDs with photonic crystal structures ” SPIE Vol. 5739 ( 2005 )
【5】 M.D.B. Charlton , M.E. Zoorob , T.Lee “ Photonic Quasi-Crystal LEDs : Design, modelling, and optimisation. ” SPIE Vol. 6486 64860R-1
( 2007 )
【6】 Mukul Agrawal , Yiru Sun , Stephen R. Forrest , Peter Peumans “ Enhanced outcoupling from organic light-emitting diodes using aperiodic dielectric mirrors ” Appl. Phys. Lett. 90, 241112 ( 2007 )
【7】 Aurélien David , Tetsuo Fujii , Rajat Sharma , Kelly McGroddy ,Shuji Nakamura , Steven P. DenBaars , Evelyn L. Hu , Claude Weisbuch ,Henri Benisty “ Photonic-crystal GaN light-emitting diodes with tailored guided modes distribution ” Appl. Phys. Lett. 88, 061124 ( 2006 )