以矽奈米柱陣列作為具疏水性質之次波長抗反射結構

Abstract

從近幾十年以來，抗反射模的概念已經普遍地落實於光學的應用上，用以抑制多餘的反射光，由其是現今發展蓬勃的太陽能產業與面板產業。例如，多層膜結構，並且廣泛地利用在光電元件中，但是卻存在黏著性較差、熱穩定性不好以及晶格不匹配...等問題。相比較之下，週期性次波長表面結構，比起傳統的鍍膜技術，具有更好的抗反射效果，像是抑制波段與角度範圍較寬、優異的疏水性和不受材料選擇限制...等優點；在製作上亦不很困難，具有相當高的發展性。到目前為止，次波長結構已經藉由各種的方法被製作在矽基板上。另外，透過加強光電元件的表面疏水性將可使元件具有自我清潔的能力，將會更具有吸引力。 本文中將會利用週期性次波長結構以結合抗反射與疏水性的特性。透過奈米米球膠體顯影技術，可以迅速地獲得奈米週期性的圖案，避免其它複雜且昂貴的奈米顯影技術，較傳統製程具備有更好的成本優勢，再配合反應離子蝕刻的過程，得到具有高度可調性的抗反射奈米柱陣列。最後，配合反射光譜儀的量測，我們成功地製作出寬波段與廣角度的抗反射結構。同時，在不同外表形貌（直徑、高度和邊壁斜度）下的奈米柱陣列，會有著接觸角與反射率的變化表現，在本文中會有更進一步的討論與分析。

The antireflection (AR) coatings are utilized to suppress undesired reflection between different optical media for various optical applications. For example, Multilayered coatings are widely used on the surface of optical and optoelectronic devices. However, it is suffered from the problems, such as poor adhesion, thermal instability, and lattice mismatch. An alternative to multilayered coatings is to pattern the surface with a periodically structured array with the periodicity smaller than the wavelength of the incident light. Compared with multilayered AR coatings, subwavelength structure (SWS) surfaces show several advantages over the conventional dielectric AR coating, including broad spectral and angular response, hydrophobicity, and durable, because the AR structures are directly etched in the surface and there are no other materials involved. So far SWSs has been fabricated on silicon have been fabricated by various methods. Moreover, enhance-hydrophobic effect on surfaces of optoelectronic devices has attracted attention because of their self-cleaning effect. In the present work, the SWSs combining AR and enhanced hydrophobic effects was reported. A simple method, which combines sub-wavelength-scale monolayer nanospheres (Colloidal lithography) with a reactive ion etching process, to fabricate AR structures of Si nanorod arrays (NRAs) was used. Spectral reflectance measurements of Si substrates with NRA SWSs showed drastic reduction in reflection over a broad range of wavelengths and a wide range of angle of incidence, demonstrating its ability to broadband and omnidirectional antireflection. The reflectivity and the contact angle as a function of diameter, height, slope of Si NWAs were discussed.