| 摘要: | 在本次研究中，我們首先先利用奈米球鏡微影術(Nanospherical-Lens Lithography, NLL)製作金屬奈米橢圓盤陣列，這個方法可以使用很低的成本以快速的大面積製程製作出所需的金屬奈米橢圓盤陣列。另外我們搭配氮化鎵材料二次蝕刻的製程技術製作出氮化鎵發光二極體的橢圓奈米柱陣列。這個奈米柱陣列先前就已經被證明可以用來製作可發出線偏振光的發光二極體。
本研究將使用這個相同的橢圓奈米柱結構，進一步測試其是否可以用來量測線偏振光。並藉著調整各項製程參數，包括橢圓的長短軸比及圓柱高等參數以達成最大的偏振選擇比。另外我們也將研究變換一些重要結構的設計，包括絕緣層以及遮光層的材料選擇，以達成更好的元件表現。另外我們也會對目標的元件進行電磁模擬分析，以進一步設計出更適合應用的元件結構。
在過去的研究中，我們知道奈米柱LED的輸出光是沒有偏振選擇的。但是，若我們在奈米柱之間，蒸鍍上一層不透光的金屬薄膜(如Ni)，作為光阻擋層，以此金屬層反射一部分的發射光，若在Ni金屬表面再鍍上一層絕緣層(如SiO2)，避免元件短路，接著再鍍上金屬電極，就可得到高偏振選擇比的奈米LED陣列。
我們發現，如果用硫化銀（Ag2S）取代Ni遮光層及SiO2絕緣層，可有效簡化製程步驟。這是因為當銀與硫化物產生化學反應後，會產生絕緣的硫化銀。在大氣的環境下，硫化銀為黑色立方晶系晶體，是一種不透光的材料，因此也可以當成光阻擋層。因此我們將Ag2S作為實驗組試著將遮光層與覺層的兩次製程簡化成一次。
雖然在實驗的分析上偏振選擇比不太理想，但最後我們模擬分析得到了一個還不錯的參數，可以使Photodetector的Polarization Difference Ratio的數值提高至0.753，換算成Selection Ratio 可以得到Ex：Ey = 7.09，我們也從模擬發現短軸要在50nm左右才會有比較高的偏振選擇比，所以我們會用用模擬的最佳參數，去製作出我們的Photodetector。
;In this research, we first use Nanospherical-Lens Lithography (NLL) to fabricate metal nano-elliptical disk arrays. This method can be used to fabricate a large-area process at a very low cost. The required metal nano-elliptical disk array. In addition, we used the secondary etching process technology of GaN material to fabricate an elliptical nanopillar array of LED. This nanopillar array has previously been proven to be used to make LED that emit linearly polarized light.
This study will use this same elliptical nanopillar structure to further test whether it can be used to measure linearly polarized light. And by adjusting various process parameters, including the ratio of the major axis of the ellipse to the minor axis and the height of the pillar, the maximum polarization selection ratio can be achieved. In addition, we will also study and change the design of some important structures, including the material selection of the electric insulating layer and the light blocking layer, in order to achieve better component performance. In addition, we will also conduct electromagnetic simulation analysis on the target component to further design a more suitable component structure for the application.
In past research, we know that the output light of nanopillar LED is not polarization sective. However, if we evaporation an opaque metal film (such as Ni) between the nanopillars as a light blocking layer, the metal layer reflects a part of the emitted light, and if a layer of Ni metal is coated on the surface an electric insulating layer (such as SiO2) is used to avoid short of components, and then metal electrodes are plated to obtain a nano-LED array with a high polarization selectivity ratio.
We found that if the Ni light-shielding layer and the SiO2 insulating layer are replaced with Ag2S, the process steps can be effectively simplified. This is because when silver reacts chemically with sulfide, insulating silver sulfide is produced. In the atmospheric environment, silver sulfide is a black cubic crystal, which is an opaque material, so it can also be used as a light blocking layer. Therefore, we took Ag2S as the experimental group and tried to simplify the two processes of the light-shielding layer and the sensory layer into one.
Although the polarization selection ratio is not ideal in the experimental analysis, in the end, we obtained a good parameter by simulation analysis results, which can increase the value of the Polarization Difference Ratio of the photodetector to 0.753, and convert it into the Selection Ratio to get Ex : Ey = 7.09, we also found from the simulation that the minor axis must be around 50nm to have a relatively high polarization selection ratio, so we will use the best parameters of the simulation to make our photodetector. |
