選擇成長不同直徑之氮化鎵奈米線

Diameter-Selective Growth of GaN Nanowires

許志偉(Chi-Wei Hsu)

指導教授 ： 陳家俊 ； 陳貴賢 ； 林麗瓊

國立臺灣師範大學/理學院/化學系/碩士(2002年)

摘要

利用金做為催化劑合成氮化鎵奈米線的瓶頸已經可以克服了。進一步控制氮化鎵奈米線的直徑可以利用金的奈米粒子做為催化劑來達成。為了防止金的奈米粒子發生預先聚合的情況，我們對矽基板的表面做了對於金的奈米粒子有較強吸附力的官能基修飾，例如：末端為硫醇或胺基的三甲氧基矽烷類。經由VLS機制成長的氮化鎵奈米線的直徑會被這些金的奈米粒子的直徑所限制住，進而得到直徑分佈均勻的氮化鎵奈米線。SEM的照片顯示出我們利用3.2±0.8 奈米， 7.2±1 奈米 與 20.4± 3 奈米的金奈米粒子當作催化劑所得到的氮化鎵奈米線的直徑分別為11±3 奈米， 16±4 奈米與 50±7奈米。利用TEM作結構鑑定的結果顯示出我們合成出來的氮化鎵奈米線與塊材的氮化鎵一致，是六方晶系的wurtzite結構，其偏好的成長方向是沿著其（100）晶面堆疊的方向。隨溫度變化的光激發螢光光譜分析發現我們所合成的氮化鎵奈米線其放光位置與各種光學性質係數與高品質的氮化鎵薄膜幾乎是一致的。CL對於單根，不同直徑的氮化鎵奈米線放光研究發現，其放光峰值的能量由隨著氮化鎵奈米線逐漸減小而有向高能量（短波長）的方向偏移的現象，但是這些氮化鎵奈米線表現出來的藍位移現象比起經由量子力學預期出現的量子限量化效應要大出許多。

關鍵字

氮化鎵 ； 奈米線 ； 陰極激發發光光譜 ； 金奈米粒子

並列摘要

Gallium nitride (GaN) nanorods were synthesized successfully by coating Au thin film as the catalyst. Further improvement, size selective growth of GaN nanorods, was achieved by using Au nanoparticles of well-defined diameter as the catalyst. To avoid pre-aggregation of Au nanoparticles, surface-modification was done by treating the surface with different kinds of thiol- or amine-terminated alkoxysilanes to increase the interaction between Au nanoparticles and substrates. The diameter of preformed Au nanoparticles defines the diameter of GaN nanorods via a Vapor-Liquid-Solid process. SEM micrographs show the obtained GaN nanowires were 11±3 nm, 16±3 nm and 50±7 nm by using Au nanoparticles of 3.2±0.8 nm, 7.2±1 nm and 20.4± 3 nm diameter, respectively. TEM analysis reveals that our results are in good agreement with bulk single crystalline h-GaN with the growth direction along (100) plane. By fitting our temperature-dependent photoluminescence (PL) results with Varshni equation, the peak positions and optical property parameters are consistent with those of high quality GaN thin films. Cathodoluminescence (CL) measurement was carried out to study the size dependence of the CL properties. A blue shift of the band-edge emission with decreasing diameter of GaN nanowires is observed. However, the magnitude of the peak shift (~40 meV) is much more pronounced than that estimated from quantum confinement theory (~1 meV).

並列關鍵字

Gallium Nitride ； Nanowires ； Cathodoluminescence ； Au nanoparticles

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