矽基板上鍺薄膜的拉曼光譜研究;Raman spectroscopy study of Germanium thin film on Silicon subtracts

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題名:	矽基板上鍺薄膜的拉曼光譜研究;Raman spectroscopy study of Germanium thin film on Silicon subtracts
作者:	陳明琪;Chen, Ming-Chi
貢獻者:	物理學系
關鍵詞:	鍺;拉曼光譜;光放射光譜;低溫;矽基板;電子迴旋共振化學氣相沉積;Germanium thin film;Raman spectroscopy;Optical emission spectroscopy;low temperature;Si substrate;ECR-CVD
日期:	2016-10-20
上傳時間:	2017-01-23 16:42:20 (UTC+8)
出版者:	國立中央大學
摘要:	本論文藉由拉曼散射光(Raman scattering)來分析調變不同製程參數(如:氣體流量、工作壓力與內磁場線圈的電流)下鍺薄膜的晶格品質與應力張量的變化，再以光放射光譜(OES)探討調整製程參數時，製程環境的電漿狀態變化情形，最後利用光激螢光(PL)檢測以鍺薄膜作為緩衝層後，磊晶於鍺上方之砷化鎵薄膜的品質好壞。由拉曼光譜可知，未退火鍺薄膜中皆出現明顯的非晶拉曼訊號，非晶的晶格結構排列無序，原子之間的作用力相較於結晶較弱，並且可能有較多的晶格缺陷，因此除了訊號出現在低能量範圍，造成拉曼訊號不對稱的肩峰(Shoulder)，鍺薄膜內的應力也因此為伸張應力。利用OES光譜的分析發現，非晶訊號產生的多寡與製程環境中的氫解離濃度成正相關，這是因為氫的自由基化性活潑，容易使基板原子形成懸鍵(Dangling Bond)，這使其他鍺原子更容易與基板上的原子鍵結，而GeH4氣體流量上升、工作壓力變大與內磁場線圈的電流變小等製程參數調變對氫解離濃度下降有著明顯的影響，因而導致非晶訊號強度上升。然而在退火後，因高溫提供足夠能量使原子能移動到正確的晶格位置，不但使晶格結構排列整齊，使非晶轉為結晶，也減少鬆散的區域而使薄膜緻密化，薄膜內的應力因而得到釋放，甚至轉為壓縮應力。光激螢光光譜的結果中顯示，利用鍺薄膜做為緩衝層的效果十分良好，砷化鎵樣品的能隙發光範圍與砷化鎵塊材的發光範圍近乎相同，且當2 μm砷化鎵樣品在能隙的發光訊號之半高寬相較1 μm砷化鎵樣品之半高寬更小，此外，砷化鎵的厚度增加到2 μm時缺陷在低能量區的訊號強度明顯的下降，整體顯示晶格品質變佳。;This work investigates the Raman spectroscopy of low temperature (180 ℃) growth germanium thin film on Si (100) substrate using electron cyclotron resonance chemical vapor deposition. The film quality and stress with various process parameters during deposition process, such as flow rates of GeH4, working pressures and inner sub-magnetic coil current, have been discussed. As the GeH4 flow rate increased, the crystallinity of Ge thin film was increased and the tensile strain was decreased. In addition, if the working pressure was increased, the Ge phonon peak position shifted to low energy more and the crystallinity was decreased, as well as the result by increasing GeH4 flow rate. However, if the inner sub-magnetic coil current was increased, the crystallinity of Ge thin film was increased and the tensile strain was decreased. Through the investigation of the OES spectroscopy, these results were depended on the hydrogen dissociation, which enhances germanium lattice structure arranged neatly during deposition process. If the flow rates of GeH4 increased, and the working pressure increased or the inner sub-magnetic coil current was decreased, the hydrogen dissociation would decrease obviously and caused the crystallinity of Ge thin film and the stress decreased. After the annealing process, the qualities of germanium thin films were getting better. The bandgap peak of GaAs grown on such germanium buffer layer was observed successfully in photoluminescence spectra.
顯示於類別:	[物理研究所] 博碩士論文

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