標題: | 無應變GaAs/AlGaAs量子點在[111]成長方向的光學異向性 Optical anisotropy of unstrained GaAs/AlGaAs quantum dots in [111] growth direction |
作者: | 廖國峰 Liao, Kuo-Feng 鄭舜仁 Cheng, Shun-Jen 電子物理系所 |
關鍵字: | 量子點;液滴磊晶;光學異向性;價電帶混成;激子;[111]成長方向;座標轉換;亮激子;暗激子;quantum dots;droplet epitaxy;optical anisotropy;valence band mixing;exciton;[111] growth direction;coordinate transformation;bright exciton;dark exciton |
公開日期: | 2012 |
摘要: | 糾纏光子對在量子資訊領域為一個關鍵的要素,而能否形成糾纏光子對的條件為精細結構匹裂要遠小於線寬(約1μeV),然而實際上因為形狀、應變、原子擴散……等原因會使精細結構匹裂變大,而無應變GaAs/AlGaAs量子點可以單純研究形狀的影響。
價電帶混成(輕重電洞混成)對光偏振、精細結構匹裂扮演著一個重要的角色。本篇論文使用簡單模型研究量子點不同晶面方向、暗激子亮激子耦合如何影響輕重電洞混成,而進一步改變光偏振。結果顯示在[111]晶面方向的光偏振小於[001]方向;在零磁場之下暗激子亮激子耦合效應極小。 Polarization-entangled pairs are a key element in the field of quantum information. The condition for generating polarization-entangled pairs is that fine structure splitting (FSS) must be smaller than the linewidth(~1μeV); however, many factors like shape, strain, atomic diffusion may increase FSS. And unstrained GaAs/AlGaAs quantum dots (QDs) is an excellent candidate easy to study due to nearly pure shape effect. Valence band mixing (VBM) plays a crucial role on optical polarization (DOP) and FSS. In this thesis, studying by using simple model how growth directions or bright-exciton (BX) and dark-exciton (DX) coupling affect component of light-hole (LH) of QDs, further changing DOP. The results show DOP in the [111] direction is smaller than the one in the [001] direction and BX-DX coupling is weak without magnetic field. |
URI: | http://140.113.39.130/cdrfb3/record/nctu/#GT070052025 http://hdl.handle.net/11536/73411 |
顯示於類別: | 畢業論文 |