以液相磊晶法研製砷化鎵量子結構之研究

The Study of GaAs Quantum Structures by Liquid Phase Epitaxy

謝明峰(Ming-Fong Hsieh)

指導教授 ： 溫武義

中原大學/工學院/電子工程研究所/碩士(2006年)

https://doi.org/10.6840/cycu200600517

摘要

在本研究中，我們使用鉍(Bi)作為溶液，以液相磊晶法進行砷化鎵(GaAs)同質磊晶之探討。除了建立同質磊晶最佳成長條件外，並嘗試改變成長飽和度以及利用選擇性成長之技術，企圖成長具有量子效應之砷化鎵同質磊晶層。
我們在使用鉍作為成長溶液、並於高度過飽和(△T=25℃)及摻雜鍺(Ge)之成長條件下所成長之砷化鎵同質磊晶層，經由表面結構與光特性的分析後，發現具有量子發光現象。針對磊晶層表面結構分別使用Normarski微分干涉顯微鏡與掃描式電子顯微鏡(SEM)進行觀察分析，發現在磊晶層的表面上除了平坦區域外，同時亦散佈著長菱形島狀結構，此島狀結構沿著一定的方向密集地排列著，並對於磊晶層的發光特性有所影響。經由光激螢光光譜(Photoluminescence)分析其光特性，所獲得之發光波長自870nm (Eg=1.43 eV)大幅度地藍位移至770nm (Eg=1.61 eV)，所對應之能量非常相似砷化鎵量子點之發光波段。除此之外，在變功率及低溫之光激螢光光譜分析中可觀察到磊晶層的發光波段並不受溫度以及功率變化影響，這亦為量子效應所具有的特性。最後經由穿透式電子顯微鏡(TEM)驗證磊晶層中的確具有量子點的存在。

關鍵字

光激螢光 ； 長菱形島狀結構 ； 量子效應 ； 液相磊晶 ； 砷化鎵

並列摘要

In this study, we use bismuth (Bi) as a solvent to grow GaAs homoepilayer by liquid phase epitaxy (LPE). In addition to investigating the optimum condition for homoepitaxy from Bi solution, we also try to grow GaAs quantum structures using a highly super-saturated solution for LPE and its high selective growth capability.
The GaAs homoepilayer, grown from the Bi solution with an extremely large super-cooling (ΔT=25 薡) and with a deliberate doping of germanium (Ge), was found to present the quantum effect for the first time. The surface morphology of epilayers was evaluated by a Normarski differential interference contrast microscope (N-DICM) and cross-sectional views of films were taken by a scanning electron microscope (SEM). It was found that numerous rhomboidal island structures distributing over the surface affected greatly the optical properties of the epilayer. The optical properties of the epilayers were analyzed by photoluminescence (PL) measurements. The luminescent peak of the epilayer was found to shift substantially to 770 nm (Eg=1.61 eV), which is close to that from the GaAs quantum dots with a bulk luminescence band peaking at 870 nm (Eg=1.43 eV). Besides, the peak positions of PL spectra were maintained during the temperature and power dependent PL measurements, suggesting a phenomenon of the quantum confinement effect. Eventually, transmission electron microscopy (TEM) observations presented a direct image of the 4 - 20 nm sized GaAs quantum dots to support our new finding.

並列關鍵字

Liquid phase epitaxy(LPE) ； Quantum effect ； Gallium arsenide(GaAs) ； Photoluminescence ； rhomboidal island structures

參考文獻

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