以奈米壓印技術開發氮化鎵量子結構晶格之數值分析研究

本論文之主題在研究一個人造二維晶體結構”量子結構晶格”，討論其製作與光學效應之研究。其結構為二維正交結構，且其間距符合布拉格繞射之條件以控制表面放射。藉由時域有限差分法的模擬環境，探討在此次波長的結構中電磁波之傳遞現象，藉由光學晶體能帶圖，找出其特徵解於週期性結構之倒晶格邊界。並且透過品質因子的模擬，來探討量子結構晶格之共振波長。最終在其共振波長下呈現出光聚束之效果。本研究使用軟性奈米壓印，實現量子結構晶格於氮化鎵/氮化銦鎵單層量子井磊晶結構中。軟性奈米壓印是將一經抗黏著鍍膜後之母片製作成一高分子軟膜，並透過其軟膜將奈米圖形轉印至所需基板上。在光致發光頻譜量測中，由於光在平面薄膜間的多重反射，導致多干涉峰值並影響量測，本研究發展一半經驗法則，藉由判斷原光致發光頻譜之干涉峰位置，產生一組餘弦校正方程式，來達到消除光在平面薄膜間的多重返射。最終，量子結構晶格實現於氮化鎵/氮化銦鎵結構中，實驗結果與模擬結果相互符合。並針對其量子結構晶格提出未來改善與其光電元件實作可能性。

關鍵字

氮化鎵；氮化銦鎵；發光二極體；有限差分時域；奈米壓印；光子晶體

並列摘要

In this dissertation, the fabrication of an artificial structure “Quantum Structure Lattice” (QSL) and its optical properties have been investigated. The QSL consists of a two dimensional orthogonal array of artificial structures with a pitch matches with the Bragg diffraction condition such that it can be used to control the surface emission. The numerical analysis technique based on “finite-difference time-domain (FDTD)” is used to explore the propagation behavior of electromagnetic waves in these sub-wavelength structures. By calculating the optical band structure, the eigenvalue can be found at the boundary of the periodic structure in the reciprocal lattice. After that, the resonant wavelength of QSL is analyzed by the quality factor simulation. Finally, the collimation effect is demonstrated by simulation at the resonant wavelength. In this study, a soft nanoimprint (soft-NIL) technique is employed to fabricate QSL in InGaN/GaN single quantum well (SQW) structures. The soft-NIL uses a polymer mold to transfer nanoscale pattern to the targeted substrate, where the soft mold is made from an anti-sticking coated Si master. In photoluminescence (PL) measurement of multiple layer heterostructures, numerous interference peaks are observed due to multiple reflections between planar interfaces, which make the interpretation of the PL spectrum difficult. A semi-empirical approach is developed. A correction cosine function is generated by judging positions of interference peaks of the PL spectrum to eliminate multiple reflections of planar multiple layered films. Finally, QSL is successfully demonstrated in InGaN/GaN SQWs. The experiment results are verified by FDTD simulations. Some improvements of pattern design and the possibility of optoelectronic device applications are discussed.

並列關鍵字

GaN ； InGaN ； LED ； FDTD ； Nanoimprint ； Photonics Crystal

參考文獻

[35] Chen, Y., et al. "Soft nanoimprint lithography." Photonics Asia 2004. International Society for Optics and Photonics, 2005.

[37] Kobrin, Boris, et al. "Molecular vapor deposition (MVD) for improved SAM coatings." MOEMS-MEMS Micro & Nanofabrication. International Society for Optics and Photonics, 2005.

[34] Xia, Younan, and George M. Whitesides. "Soft lithography." Annual review of materials science 28.1 (1998): 153-184.

[2] Yim, W. M., et al. "Epitaxially grown AlN and its optical band gap." Journal of Applied Physics 44.1 (1973): 292-296.

[3] Nakamura, Shuji, et al. "Blue InGaN-based laser diodes with an emission wavelength of 450 nm." Applied Physics Letters 76.1 (2000): 22-24.

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以奈米壓印技術開發氮化鎵量子結構晶格之數值分析研究

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