https://scholars.lib.ntu.edu.tw/handle/123456789/173864
標題: | 前瞻性量子元件 | 作者: | 林浩雄 | 關鍵字: | 分子束磊晶;含銻化合物半導體;銻砷化 鎵量子井;砷化銦量子點;量子點雷射;彎曲係數;價電帶差比;調變頻寬;雷射等效電路;雙能態現 象;molecular beam epitaxy;Sb-based compound semiconductor;GaAsSb quantum well;InAs quantum dot;quantum-dot laser;bowing parameter;valence-band-offset ratio;modulation bandwidth;laser equivalent circuit;two-state phenomenon | 公開日期: | 31-七月-2005 | 出版社: | 臺北市:國立臺灣大學電子工程學研究所 | 摘要: | 本計畫包括以分子束磊晶法在砷化鎵基板上成長 銻砷化鎵/砷化鎵第二型量子井、砷化銦鎵/砷化銦 量子點結構雷射二極體的研究、以及量子點雷射動 態調變特性等研究。在第二型量子井的部分我們利 用共振腔長度調整雷射波長,並利用雷射增益的計 算來模擬銻砷化鎵/砷化鎵第二型量子井能帶排列 的關係。我們獲致的GaAs0.64Sb0.36/GaAs量子井主動 層其GaAsSb之彎曲係數為 -1.31 eV,而價電帶差與 能隙差比為1.02。在量子點雷射結構的部分,我們 發展了一種新型的耦合量子點主動層結構。與非耦 合量子點結構相比,此種結構的雷射特性並沒有劣 化,但其波長可以延長。在量子點雷射動態特性研 究的部分,我們創新提出量子點雷射之小訊號等效 電路,並且可使用P-SPICE來模擬阻抗響應與光學 響應,並且藉由與已知的雷射調變特性模擬來驗證 此模型的有效性。此外,研究量子點雷射雙能態頻 譜動態解析也是首度被實驗觀察到。激發態雷射動 作早於基態雷射行為,此與理論的模擬是一致的。 The studies of this project include the molecular beam epitaxial (MBE) growth of GaAsSb type-II quantum well (QW) and InGaAs/InAs quantum dot (QD), and the modulation properties of QD laser diodes. In the first portion, GaAsSb/GaAs type-II QW lasers were fabricated. Because of the band-bending effect, the emission wavelength of the laser has a blue-shift as the cavity length is shortened. We utilized this effect to investigate the band line-up of the GaAsSb/GaAs QW. Through a simulation based on solving the Poisson and Schrödinger equations simultaneously for the band structure and optical gain of GaAsSb/GaAs QW, we found that the valence band offset ratio (Qv) of the unstrained GaAs0.64Sb0.36/GaAs is 1.02, and the unstrained band-gap bowing parameter of GaAsSb is -1.31 eV. For QD lasers, we present a novel coupled-QD structure. The structure contains two closely coupled InAs QD layers and one InGaAs capping layer on top QD layer. Cross-sectional TEM images reveal that the coupled-QDs have larger size and lower density as compared with the controlled sample. The laser of coupled-QD structure demonstrates longer emission wavelength and slightly higher threshold current density than its counterpart, which indicates the coupled-QD structure is promising for long wavelength applications. In the portion of the dynamic properties study, the small-signal equivalent circuit model of quantum-dot lasers is proposed for the first time. We use P-SPICE to simulate their impedance and optical responses. The validity of this model is confirmed by the well-known laser modulation properties. Finally, spectrally resolved dynamics of two-state lasing in QD lasers is also experimentally demonstrated for the first time in this study. The onset of excited-state lasing prior to ground-state lasing is consistent with our theoretical prediction. |
URI: | http://ntur.lib.ntu.edu.tw//handle/246246/20047 | 其他識別: | 932215E002024 | Rights: | 國立臺灣大學電子工程學研究所 |
顯示於: | 電子工程學研究所 |
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932215E002024.pdf | 456.05 kB | Adobe PDF | 檢視/開啟 |
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