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標題: | 銻磷砷化鎵材料特性研究 Material Properties of GaAsPSb |
作者: | Han-Sheng Tsai 蔡漢聲 |
指導教授: | 林浩雄 |
關鍵字: | 光激發螢光,時間解析光激發螢光,拉曼散射, Photoluminescence,Time-Resolved Photoluminescence,Raman Scattering., |
出版年 : | 2012 |
學位: | 碩士 |
摘要: | 本論文以二次離子質譜儀分析法得到樣品的成分組成;使用高解析度X光繞射儀進行倒置晶格圖譜,得到晶格結構參數;使用X光精細結構吸收光譜分析晶體內部資訊,並與價力場模型的理論記算結果比對分析;為了正確取得X光精細結構吸收光譜的實驗數據,建立了一套資料選取方法;利用變溫光激發螢光頻譜、低溫變光激發強度頻譜以及拉曼散射頻譜研究銻磷砷化鎵材料的光學特性,並使用時間解析光激發螢光頻譜得到實驗樣品的次要載子生命週期。
從X光晶細結構吸收光譜實驗資料中可發現,由於實驗樣品成分較低、厚度較薄等因素,使得在萃取實驗數據上的準確性降低。因此我們嘗試各種不同的資料選取方式,結果顯示我們必須在擬合過程中一次只改變單一變因,並先將最後所要擬合的資料曲線選取到各波峰皆明顯區別出來,再進行遞迴式資料選取以獲得最佳結果,在此我們建立一套可信且合理的X光晶細結構吸收光譜資料處理方法。 光激發螢光頻譜的實驗之中,我們量測砷化鎵基極 HBT變溫光激發螢光頻譜,並參考文獻利用線性外差低能量斜邊方式,得到在各溫度下實際放光能量值。使用Varshni equation擬合資料點,得到常溫300K時的放光能量,計算能隙縮減(BGN)量以證明此方式的合理性,最後將此方法套用到以銻磷砷化鎵基極HBT的變溫光激發螢光頻譜分析上,得到在常溫300K的放光能量為1.247eV。 時間解析光激發螢光頻譜實驗,利用變溫光激發螢光頻譜實驗得到的常溫放光能量值,量測HBT結構基極層在特定放光波長下的次要載子生命週期,四元材料銻磷砷化鎵基極次要載子生命週期為16.6ps。 拉曼散射光譜實驗,比較無摻雜、重摻雜的單層塊材結構與層狀結構,在激發光強度改變之下的線形變化。單層結構隨著激發光強度變強各峰值強度等速度增加,層狀結構由於存在接面內建電場,我們認為激發光強度增強時光激發載子也隨之增加,但由於內建電場游離光激發載子,導致部分內建電場被游離的電子或電洞屏蔽,促使LO模態強度相對較弱,此外我們以合金位能擾動以及非簡諧性震盪解釋半寬不對稱與峰值偏移。 In this thesis, we use secondary ion mass spectroscopy to acquire mole fractions of our samples; Using high resolution X-ray diffraction to do the reciprocal space mapping, and obtain the information about lattice structure; Using Extended X-ray absorption fine structure experiment to investigate the information about bond length. Besides, we calculate valence force field model to the result of Extended X-ray absorption fine structure experiment; In order to acquire a reasonable set of data from EXAFS experiment, we construct a data selection process; Using low temperature power dependent PL, temperature dependent PL, and Raman scattering experiment to acquire optical properties of material; And using Time resolved PL to acquire the minority carrier lifetime of HBT base structure. In EXAFS experiment, we found that if our samples are thin or have low mole fraction of the element we want to detect, it would be difficult to obtain a reasonable set of data. So we test different regions of data selections, conclude that we can only change one parameter at a time, and do data selections repeated in both R-space and K-space. In the end, judge the quality of data by R-factor. In Photoluminescence experiment, we measure the temperature dependent PL of GaAs base HBT structure, by doing linear extrapolation of low energy shoulder of spectrum, we can obtain emission energy for each temperature we measured, then using Varshni equation to fit data point in order to get room temperature emission energy, compared it with BGN model to modify this process is adoptable. In the end, using this process to obtain the room temperature emission energy GaAsPSb base HBT structure, which is 1.247eV. In TRPL experiment, using the room temperature emission energy obtained from PL to measure minority carrier lifetime of pre-selected wavelength, the minority carrier lifetime of GaAsPSb base is 16.6ps. In Raman scattering experiment, we discuss the differences between one layer structure and multilayer structure of the influence from excitation power. The result shows there might exist electric field in multilayer structure, causing photo excited electron-hole pair dissociation, and screening a partial of electric field, leading to the different growth rate of each peak. Besides, we use alloy potential and anharmonicity effect to describe asymmetry and peak shift. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/64866 |
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顯示於系所單位: | 電子工程學研究所 |
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