本論文針對奈米級半導體材料在微腔體內之發光性質研究。研究動機除了腔體高Q值的興趣外,更利用半導體奈米材料的特殊發光性,結合腔體成為光學應用。所利用奈米粒子為可發光的螢光粒子—CdSe(5.6 nm)作為發光光源。此CdSe外包裹ZnS作為保護層,再加以利用硫醇分子(MPTS),利用Zn-S的化學鍵結,成功結合CdSe粒子與腔體球,成為共振腔體。腔體球的部分,選用了大小兩種腔體,大腔體為玻璃球(3~10 micrometer),小腔體為silica球(0.4 micrometer)並且在大腔體球內成功觀測到腔體模組的現象(cavity mode)。光性分析的部分,主要利用Argon雷射為主要的激發光,激發螢光粒子使得光源在玻璃球上共振,並架設微區域光致激發螢光光譜(Micro- Photoluminescence)裝置,量測單一腔體結構的光性。 本文的重點在於觀測球形的腔體模,也稱為回音壁波(Whispering Gallery mode, WGM),利用散射平面波的Mie theory作為理論背景,並成功觀測到下列現象:WGM模組態(發光在∼620 nm)、WGM模的spacing(37 meV)、Quality factor(Q ~ 500 )、Purcell Factor(F ~9.1)、不同偏振方向(TE/TM)分析、類似自發輻射的現象(threshold voltage ~ 320 kW/cm2)、低溫CdSe的光譜等等。將奈米螢光粒子結合腔體球,觀測球形的共振模,為本文的重點。並期許未來此種高Q值的雷射腔體,能作為光學上應用元件。
This thesis studied the photoluminescent properties of semiconductor nanomaterials in photonic microcavities. Glass spheres (3~ 10 micrometer) covered CdSe nano-dots (5.6 nm) are applied to microcavities. The emission (~620 nm, visible light spectrum) of the single microcavity is measured by Micro-PL system. Cavity mode, called Whispering Gallery Mode (WGM), is observed by us and explained by Mie theory. Observed phenomenon: Cavity enhancement (20 times), spacing between WGM (37 meV), small mode volume (1.3 × 10-12 cm3), spectrums of different polarizations (TE / TM), stimulated emission (320 kW/cm2), low temperature CdSe spectrum etc.