The Surface Morphologies and Optical Characteristics of GaSb/GaAs type-II Quantum Dots

Type-II銻化鎵/砷化鎵量子點結構之表面形貌及光學特性

麥樹成

指導教授 ： 吳孟奇 ； 林時彥

國立清華大學/電機資訊學院/電子工程研究所/碩士(2010年)

https://doi.org/10.6843/NTHU.2010.00080

摘要

In this thesis, the surface morphologies and optical characteristics of GaSb QDs grown under different growth parameters are investigated. Without any observation of GaSb QDs with coverage lower than 2.0 mono-layer (ML), the critical thickness of GaSb QDs is determined to be ~ 2.5 ML by using the in situ reflection high-energy electron diffraction measurement (RHEED). By decreasing the V-III ratios during GaSb deposition, the growth mode would gradually change from interface-miss-fit-array (IMF) to the Stranski–Krastanov (S-K) growth mode. It is observed that to obtain GaSb QDs with S-K growth mode, the V/III ratio should be kept at ~1.2. The results of Sb soaking after GaSb QD growth have demonstrated that with longer soaking time, enhanced PL intensity is observed, which has revealed lower defect formation is obtained with longer soaking times. The influence of growth temperatures is also investigated. It is found that a sample with higher growth temperature 490 oC is of the best optical characteristics. The influence of As atoms on the morphologies of GaSb QDs is investigated. Without any special treatment, GaSb QRs are observed in the embedded GaSb layer even when the uncapped layer reveals QD-like morphologies. The phenomenon suggests that insufficient Sb atoms on the GaSb QDs would lead to the QD-to-QR transition as in the case for the embedded GaSb layers. With extended Sb soaking time 75 sec. after GaSb deposition, QD structures could be maintained for the embedded GaSb layers.

關鍵字

量子點 ； 砷化鎵 ； 銻化鎵 ； Type 2

並列摘要

無資料

並列關鍵字

QDs ； GaAs ； GaSb ； Type II

參考文獻

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