氧硒化鋅變溫拉曼光譜研究; Temperature-dependent Raman scattering of ZnSeO

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题名:	氧硒化鋅變溫拉曼光譜研究;Temperature-dependent Raman scattering of ZnSeO
作者:	林坤政;Lin,Kun-Zheng
贡献者:	物理學系
关键词:	氧硒化鋅;變溫拉曼光譜;拉曼光譜
日期:	2013-07-29
上传时间:	2013-08-22 11:46:47 (UTC+8)
出版者:	國立中央大學
摘要:	本論文所研究之氧硒化鋅氧濃度範圍0%≦x≦11.6%。因為氧在硒化鋅的溶解度有限情況下，增加了長晶的困難度。Nabetani團隊有提到氧硒化鋅合金氧濃度至多到6.4%[1]。本研究所使用的系列樣品氧濃度最高到11.6%。先前的研究中，光激發螢光光譜(PL)中發現室溫能隙隨氧參雜比例變化符合能帶互斥理論[3]。並且高參雜下螢光強度下降，半高寬變寬[7]。7%以上沒有辦法觀察到PzR微分訊號[8]，代表高參雜下晶格出現了些問題。因此之後我們以拉曼光譜研究樣品晶格特性，並進一步探討變溫拉曼光譜。在10K拉曼光譜中，因為聲子頻率受基板應力與有效質量(effective mass)影響，參氧後聲子頻率往低能量移動，氧濃度大於2.2%移動趨緩。氧濃度大於9.3%後應力釋放，以有效質量主導，聲子頻率開始往高能量移動。在變溫拉曼方面，氧濃度上升，非諧和效應增加，聲子頻率隨溫度變化量增加。同時氧濃度上升，晶格亂序加劇，LOZnSe寬度增加。生命期方面，氧濃度上升LOZnSe生命期下降，代表光學聲子衰變為聲學聲子時間變短。 The oxygen concentrations of ZnSe1-xOx alloys studied in this thesis are in the range of 1.5%x11.6%. Because of the limited oxygen solubility, Nabetani had proposed that ZnSeO alloy composition up to 6.4%. Our highest concentration up to 11.6%.In our previous study indicate the results of photoluminescence (PL) indicate that the relationship between band gap and oxygen composition can be well described in the framework of band anti-crossing model (BAC model). However, the full width of half maxima (FWHM) of signals becomes broader and the intensities become weaker in the higher O concentration range. These results indicate that the crystal structures may have changed. Thus we investigated the crystal structure via Raman spectrum. In 10K Raman scattering experiments, the phonon frequency is influenced by strain and effective mass. With ZnSe mixes O, the phonon frequency become slower than ZnSe, but when oxygen concentration higher than 9.3%, the frequency is dominated by effective mass. The phonon frequency becomes faster. In temperature-dependent Raman scattering, we can find as the oxygen concentration increases, the anharmonic effect will increase. Besides, the FWHM of LOZnSe becomes broader than ZnSe. In the end, we will discuss optical phonon life time. When increasing the oxygen concentration, the life time will become shorter than ZnSe.
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