具有奈米結構的金屬薄膜作為透明電極之理論分析

Abstract

現代科技文明中，透明導電電極廣泛地應用在各式光電元件中。目 前主流透明電極為金屬氧化物材料，其中又以氧化銦錫為最大宗。但 是氧化銦錫含量稀有，以致於價格居高不下，因此相關產業不斷嘗試 使用其他低成本的材料來取代氧化銦錫作為導電電極。本篇論文嘗試 使用奈米結構金屬薄膜作為透明導電電極，將金屬的表面電漿特性列 入考量，利用耦合模態法分析奈米結構金屬薄膜的光穿透特性，並藉由簡化模型定義了奈米微結構的等效片電阻。以這些分析結果，我們提出一個設計結構範例，其光穿透率從可見光區域到紅外線區域都在90% 以上且片電阻的值可低至0.015662 Ω/sq。同時，我們也模擬了多狹縫週期和不同金屬作為材料的結果。和其他材料做比較，奈米結構金屬薄膜具有取代氧化銦錫作為透明導電電極的潛力。藉由理論分析，我們提出了奈米結構金屬薄膜作為透明導電電極的設計準則。綜合本篇論文的討論結果，我們能夠使用具有奈米結構的金屬薄膜設計一個 可用的透明電極，其具有高光穿透率以及低片電阻，若可結合現代製程及使用低價金屬則可以有效降低生產成本。

Transparent electrodes are widely used in optoelectronic devices. Nowadays, the commonly used materials for this purpose are metal oxides. Tin doped indium oxide (ITO) is the dominant material in this category. The problems of ITO mainly centered on its scarcity of supply, and its ceramic nature. Thus, there has been interest in replacing them. In this study, we demonstrate theoretical analysis of optical properties of nanostructure metal films with coupled-mode method and its effective sheet resistance defined by a simplified model. The surface plasmon properties of metal are considered. An example of transmission over 90% across visible range to IR range and Rs of 0.015662 Ω/sq is reported. The structures with more than one slit in a period and with different metal are also calculated in our formalism. The nanostructure metal films shows potential for replacing ITO as transparent electrodes when comparing with other materials. By the theoretical analysis, we provide design principles of nanostructure metal film-based transparent electrodes. Concluding the results of this thesis, we are able to design a qualified transparent electrode, which possess high transparency and low sheet resistance. If it is possible to combine modern process and use low priced metal the production cost can be lowered greatly.