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標題: | 銻砷化鎵/砷化鎵量子井與應力補償結構之研究 Studies on strained and strain-compensated GaAsSb-related quantum well structures |
作者: | Cheng-Tien Wan 萬政典 |
指導教授: | 林浩雄 |
關鍵字: | 砷銻化鎵,量子井,模擬, GaAsSb,quantum well,simulation, |
出版年 : | 2006 |
學位: | 碩士 |
摘要: | 本篇論文的主題為砷銻化鎵/砷化鎵量子井結構之特性探討,我們探討位障層厚度之影響,在載子濃度4x1012cm-2時,5nm結構材料增益為600cm-1,80nm結構材料增益為400cm-1,使用5nm結構可使起振電流降低一半,並可減低藍移現象;量子井材料部分我們探討了加入銦形成砷銻化銦鎵材料用以改變能帶排列情形之增益特性,在加入少量銦形成In0.02Ga0.98As0.66Sb0.34時確實可以有效增加電子電洞複合效率,降低起振電流約12%,延後放光躍遷由低能階往高能階主導之情形,並且發光波長仍可達到1300nm。另外,由於量子井砷銻化鎵之壓縮應力過大導致無法成長多週,必須用應力補償結構,我們也成長了一系列樣品做比較探討,發現使用應力補償確實可以縮小光激螢光光譜之半寬,應力補償結構之半寬為43.7meV,較無應力補償結構之半寬71.4meV為佳,並由模擬計算多週量子井可得週數較多時,起振電流較大,注入載子後增益增加速度較快,放光波長也可以較長。 In this thesis, we report the optical properties of strained and strain- compensated GaAsSb-based quantum well (QW) structures. First, we investigated the effects of barrier thickness on the gain spectrum of GaAsSb/GaAs QW. For a QW with a well thickness of 7 nm and a carrier density of 4x1012 cm-2, the material gain can be enhanced from 400 to 600 cm-1 as the GaAs barrier thickness is decreased from 80 to 5 nm. The reduction in barrier thickness can decrease the threshold carrier density by 50% with a constrained blue-shift in peak wavelength. Second, we investigated GaAsP/GaAs/GaAsSb strain-compensated QW structure. The introduction of tensile-strained GaAsP in GaAsSb/GaAs system can compensate the compressive strain resulted from GaAsSb and makes multiple quantum well (MQW) structure possible. Our simulation results show that MQW structure has larger threshold carrier density, higher differential gain and less blue shift in peak wavelength as compared with single QW structure. Preliminary experimental study reveals that the strain-compensated MQW structure has narrower photoluminescence linewidth than the ordinary MQW structure, indicating the better interface properties due to strain compensation. Third, we studied InGaAsSb/GaAs QWs. Incorporating indium into GaAsSb can reduce the conduction band offset between the GaAsSb and GaAs and enhance the wavefunction overlap of electron and hole. However, it also results in blue shift in gain peak. A trade-off between gain and blue-shift is considered. As the indium composition is 0.02, the threshold carrier density can be reduced by 12% while the emitting at 1300 nm is sustained. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/32481 |
全文授權: | 有償授權 |
顯示於系所單位: | 電子工程學研究所 |
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