斜向入射電子束蒸鍍法製作超低折射率奈米孔洞薄膜以及其在布拉格反射鏡和抗反射薄膜上的應用

Fabrication of Ultra-Low-Refractive-Index Nanoporous Thin Film by E-Beam Oblique-Angle Deposition and The Applications for Distributed Bragg Reflector (DBR)/ Anti-Reflection (AR) Thin Films

劉俊廷(Jun-Ting Liu)

指導教授 ： 李允立

國立臺灣大學/電機資訊學院/光電工程學研究所/碩士(2008年)

https://doi.org/10.6342/NTU.2008.00982

摘要

折射率是光學元件中最重要的光學性質。對於許多光學元件來說如望遠鏡和眼鏡，還有光學鍍膜如布拉格反射鏡和抗反射薄膜，折射率匹配的設計主宰了整個光學應用的表現。事實上對於光學元件中，某些特定折射率數值的需求是常被需要的。但是等效折射率數值常被用來彌補這個需求的空缺。斜向入射電子束蒸鍍法可以用來製造可調變折射率和超低折射率的奈米孔洞薄膜。我的實驗中奈米孔洞的薄膜是利用二氧化矽，二氧化鈦和矽蒸鍍源蒸鍍而成，並分別討論他們的奈米孔洞結構，折射率的變化，奈米孔洞結構的薄膜厚度減少量和空洞佔奈米孔洞薄膜的比率。其中我們做出最低的折射率是折射率等於1.08的奈米孔洞薄膜。
在奈米孔洞薄膜的應用上面，已經利用只有二氧化鈦的材料製作出單對和雙對在矽基板的布拉格反射鏡並且將反射率提高至74%。而在載玻片上面製作的單層抗反射層也將反射率從原先中心波長的7%下降至0.1%。四層的漸近折射率抗反射層在矽基板也使反射率降至小於5%的區域從527奈米到1279奈米，反射率小於1 % 的區域從618奈米到972奈米，這個抗反射層提供了廣波段的抗反射頻譜圖。
奈米孔洞氧化的現象在之前也被討論過，我的實驗主要針對因為不同蒸鍍的角度對於不同氧化程度的量測，而奈米孔洞氧化現象對於抗反射鍍膜上面的影響也被證實，這裡並且提供一個簡單的方法去避免這種氧化問題。

關鍵字

斜向入射電子束蒸鍍法 ； 抗反射鍍膜 ； 奈米孔洞薄膜 ； 布拉格反射鏡 ； 氧化

並列摘要

The refractive index is the most important property for optical devices. For optical devices, i.e. telescopes and eyeglasses, optical coatings, i.e. Distributed Bragg Reflector (DBR) and Anti-Reflection (AR) coating, the designs of the refractive index matches are dominating the performance of those optical applications. In reality, some desires of specific refractive index values are often needed for specific optical device designs. However, the effective refractive index can be used to redeem these refractive indices desires. E-beam oblique-angle deposition is a technique to fabricate the tunable and ultra-low-refractive-index nanoporous thin films. In my experiments, the nanoporous thin films deposited by SiO2, TiO2 and Si evaporation sources are discussed with the structure analysis, refractive indices change, reduction thickness and porosity of nanoporous thin films. The lowest refractive index of these nanoporous thin film is as low as 1.08.
In my application experiments, the single and double pair DBRs on silicon substrate deposited by only TiO2 evaporation source were successfully fabricated and enhancing the reflectivity above 74%. The reflectivity at central wavelength of single layer AR coating on glass slider substrate is eliminated from R= 7% to R=0.1%. The gradient-index 4-layer modified quintic AR coating on silicon substrate also diminish the reflectivity R< 5% from 527 nm to 1279 nm and reflectivity R< 1% from 618 nm to 972 nm. It provides a broad-band very low reflection region.
Oxidation phenomena of silicon nanoporous thin film were discussed before. Discussion for oxidation degree of different nanoporous thin film with different incident flux angles is made in my experiment. Moreover, the effect of degradation of silicon nanoporous thin film for optical AR coating is demonstrated and I provide a simple way to solve this kind of problem.

並列關鍵字

oblique-angle deposition ； Anti-Reflection (AR) coating ； nanoporous thin film ； Distributed Bragg Reflector (DBR) ； oxidation

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