- 學位論文
金催化成長氧化鋅奈米線結構之變功率光致螢光光譜研究
Photoluminescence of Zinc Oxide Nanowires Grown with Gold Catalyst
摘要
在本實驗中，使用金薄膜或奈米金粒子催化碳熱還原法於矽(111)基板上生長氧化鋅奈米線。除了熱退火金薄膜上生長的奈米線直徑約70~150 nm，其餘所有生長出的奈米線，直徑皆落在約70~90 nm。由於奈米線之間彼此有纏繞的情形，因此我們無法由SEM準確判斷奈米線長度，但可判斷出平均長度約在10-5 m數量級。 在光激螢光光譜中，所有樣品皆在UV 波段的近能隙發光峰值出現隨激發功率增強而紅移的現象，紅移範圍在377~407 nm 之間，隨著不同樣品而紅移範圍大小不一。這可能是由於載子行為由激子轉變為電子-電洞電漿態所主導。 在發光強度方面，皆符合power law。UV 光α 值(power law 中的指數)在1.387~1.979 之間，可見光α 值在.471~0.807 之間，這些數據顯示我們的光散射程度和比表面積與文獻上的奈米棒和微米粒子較接近。從UV 光和可見光比值的α 值，顯示無法從單一激發功率的光譜圖判斷樣品結晶品質的好壞。由於我們的樣品的α 值變動範圍較大，顯示可能還有其他還未控制的變因影響奈米線的生長。
並列摘要
In this experiment, ZnO nanowires were grown on Si (111) substrates by the carbon thermal reduction method with catalytic gold nanoparticles or thin films. The diameters of the nanowires were about 70 ~ 90 nm. Due to that the nanowires were entangled with each other, we could not determine the lengths of nanowire from the scanning electron microscopy (SEM) images accurately. However, the lengths were observed in the order of magnitude of 10-5 m. In the photoluminescence (PL) spectra, all samples showed that the peak of the near-band edge emission (UV) has a red-shift with the increased excitation power. The red-shift range is from 377 nm to 407 nm. It may be because the dominate carrier behavior was mainly from electron-hole plasma instead of excitons. The dependence between the PL intensity and the excitation power follows the power law. The α value (exponent) for the UV emission is from 1.387 to 1.979; The α value of the visible emission is from 0.471 to 0.807. These data show that the light scattering behavior and the specific surface area of our samples was similar to those of the nanorods and microparticles studied in the previous literatures. The α value of the ratio of the UV intensity to the visible intensity shows that the quality of the samples cannot be judged by one single excitation power spectrum. The wide range of the α values shows that some factors may still not be well controlled in the growth of nanowires.