新穎型可發光電子束光阻與磁性電子束光阻之開發研究與應用

Abstract

本研究目前已經開發數種新穎的電子束光阻，例如可發光型電子束光阻：CdSe/PMMA光阻、MEHPPV/PMMA光阻和P3HT/PMMA光阻，以及磁性光阻：La0.7Sr0.3MnO3光阻和La0.6Ca0.4MnO3光阻。相較於CdSe/PMMA光阻，本研究所開發的P3HT/PMMA光阻展現較高的解析度，且具備較好的互溶性和熱穩定性。而對於磁性光阻系統而言，La0.6Ca0.4MnO3光阻相對於La0.7Sr0.3MnO3光阻展現了較佳的磁性性質。利用這些光阻，我們可以輕易的用電子束顯影技術，製作出奈米結構的圖案，再運用表面電漿共振理論和光子晶體的原理，來調控材料的光學性質和増強發光效率。 對於光子晶體的應用，我們利用電子束曝光La0.7Sr0.3MnO3光阻來製備二維的光子晶體。在製程中，La0.7Sr0.3MnO3光阻使用環保無毒性的水作為顯影劑。而且因La0.7Sr0.3MnO3光阻的高折射率(n=2.38)使其在光子晶體的應用上，容易獲得完全能隙(complete bandgap)的優點。此外，我們也可以藉由調整電子束曝光的劑量，於一個固定的設計圖案上，來調控La0.7Sr0.3MnO3光子晶體的能帶位置，而目前此能帶位置範圍可以涵蓋整個可見光的波長區段(450~680 nm)。 面電漿共振理論的應用，我們除了利用電子束顯影的技術來調整CdSe/PMMA光阻的幾何結構外，並使用熱蒸鍍來製備表面覆蓋金的CdSe/PMMA陣列。當我們調整金陣列的幾何結構時，因表面電漿效應，使得吸收波長隨著金陣列結構改變而有位移的情形，當此陣列的吸收波長符合激發波長時，螢光強度將會增強達2.5倍。而本論文同時也將金蒸鍍於La0.7Sr0.3MnO3的週期結構上，利用Extinction性質的平面定位掃瞄的量測，可以明顯判別出具有週期結構和不具週期結構之間的差異性；並藉由調控金的表面電漿效應，利用光子數平面定位掃瞄的量測，可以發現因表面電漿效應的影響使得P3HT/PMMA的光致發光產生的單位面積光子數，大幅增強20倍。

We have successfully developed several novel luminescent electron beam resist systems and magnetic electron beam resist systems. The luminescent resists are made from CdSe/PMMA composite, MEHPPV/PMMA blend or P3HT/PMMA blend. The magnetic resist are made from sol-gel precursor of La0.7Sr0.3MnO3 or La0.6Ca0.4MnO3. Among the luminescent electron beam resist systems, P3HT/PMMA electron beam resist exhibits higher resolution than that of CdSe/PMMA composite resist does. The compatibility and stability of P3HT/PMMA is also better than that of CdSe/PMMA. For the magnetic electron beam resist systems, the same magnetizing field imposed on La0.6Ca0.4MnO3 causes larger magnetization than it on La0.7Sr0.3MnO3. Periodic arrays can be fabricated using these resists and further tailored by surface plasmons or photonic crystal to enhance and modulate their optical properties. For the photonic crystal applications, we have created unique periodical structures using water-developable La0.7Sr0.3MnO3 electron beam resist using an environmentally-friendly- one-step method. Both positive and negative patterns are readily fabricated by only varying the electron beam dosage. Different reflectance spectra of the patterned La0.7Sr0.3MnO3 in the visible light range (450 ~ 680 nm) can be obtained with a fix design pattern. When considering the surface plasmon applications, we can tune the surface plasmon resonance by adjusting the lattice constant and the column diameter of the patterned array to coincide with the excitation wavelength. Since there occurs an efficient energy transfer from the gold surface plasmon to the CdSe quantum dots, the composite film exhibits enhanced photoluminescence intensity up to 2.5 times at 570 nm. Therefore, our approach provides excellent opportunities for the CdSe quantum dots usage in high efficient optoelectronic devices. Our research also looks into the surface plasmon effect on Au coated periodic structured La0.7Sr0.3MnO3. From the extinction mapping measurement, we can easily distinguish the difference between the material with and without periodical structures. Also, by controlling the gold surface plasmon, we discover 20 times increases in photo counts of P3HT/PMMA.