光子晶體的簡易製造法

Abstract

本文探討以膠體粒子自組裝現象，製造三維的光子晶體。利用離心力與毛細作用力，將膠體粒子排列在設計過的基板上。期望降低三維光子晶體的缺陷問題，並在短時間內得到排列一致的堆積結構，提升其應用價值。 實驗分成兩部份：第一，基板的製作。將基板設計成以微通道的方式，引導奈米膠體球排列；第二，讓膠體球在不同的條件下堆積成光子晶體結構。使用矽基板與PDMS做出具有通道的基板，再以旋轉塗佈法、開放式和覆蓋微流體通道的方式，將聚苯乙烯(PS)或二氧化矽(SiO2)膠體粒子排列在通道內。三種方式，各具不同的特點：旋轉塗佈在最短時間內得到小範圍光子晶體；毛細作用力可以得到最大片低缺陷結構；覆蓋式PDMS通道可以精確控制晶體成長的大小。 在面積五乘五厘米的基板上，可以看到直徑兩百奈米至三百五十奈米的聚苯乙烯膠體球，在通道中堆積成有顏色的晶體。經可見光光譜的測量，每一種直徑的膠體粒子，都會得到一狹窄的反射峰(reflectance peak)；直徑大於四百奈米之膠體球，會呈現混合性的墨綠色光澤，在可見光範圍得到數個峰值。電子顯微鏡影像顯示，膠體球在通道內形成低缺陷的排列結構。 本實驗以最簡便的方式，利用微米等級的通道，成功的讓膠體粒子短時間內形成低缺陷的光子晶體。希望未來用微通道成長晶體的方式，能控制膠體球成長的外形。

This article presents a simple process to grow photonic crystals by colloidal spheres. Colloidal spheres are array in designed channels with spin-coating, capillary force. Using additional forces and designed substrate, it is expect to grow low defect photonic crystals in a short time and put it in more use. The experiment is derived into two parts: First, substrates fabrication. Design substrate that can make colloidal spheres into order array; the second, controlling parameter to produce low defect photonic crystals. There are three types growing photonic crystals in silicon wafer and PDMS channels: (1).spin coating, (2).capillary force channels and (3).covering fluidic channels. Each type has its own characteristic. Spin coating can growth small area photonic chip in the shortest time. Capillary force channels can easily growth low defect crystals. Covering fluidic channels can precise control growing area of crystals. As the result of colloidal array, there are different colors with different colloidal sphere diameter ranging 200nm to 350nm. Each size has a sharp peak in visible light range. Photonic crystals with diameter large than 400nm are present mixed blackish green color. We find several peaks in visible light range. SEM images show low defect and single type array in large area of the crystals. It is successfully to arrange colloidal sphere in micrometer channels. Using the simple process we can control shape of the crystals. As this result, it might form other shapes of photonic crystals to put it in other use.