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題名 鉍銻碲硒系列拓樸絕緣體長成與物理特性之研究
Synthesis and Characterization of Topological Insulator Bi1.5Sb0.5Te3-ySey , y=1.1, 1.2, 1.4 and 1.6作者 王冠淵
Wang, Kuan Yuan貢獻者 陳洋元
Chen, Yang Yuan
王冠淵
Wang, Kuan Yuan關鍵詞 拓樸絕緣體
Topological Insulator日期 2012 上傳時間 2-九月-2013 16:56:56 (UTC+8) 摘要 三維拓樸絕緣體，其擁有表面可以導電但內部卻屬於絕緣體的特殊性質；近年來成為熱門的研究領域。拓樸保護表面態此種獨特性質使得拓樸絕緣體有潛力成為自旋電子學研究材料。在已發表的文獻中可以得知Bi2Te3系列材料已經被證實為拓樸絕緣體。我們製作了一系列的Bi1.5Sb0.5Te3-ySey材料，希望藉由硒元素的摻雜改變在狄拉克錐體附近的能帶結構以更詳加了解拓樸絕緣體表面性質以及其物理特性。他們的晶格結構為菱形六角面體；當摻雜量y=1.6時，a軸及c軸的晶格常數分別為4.25 Å以及29.80 Å；同時也發現晶格常數隨著硒元素的摻雜量提高而逐漸遞減。為了更進一步了解拓樸絕緣體物理性質，我們做了電阻率、磁阻以及霍爾效應的量測以及分析。電阻率的結果顯示，樣品在高溫時呈現絕緣體的電阻性質，但在低溫時表面態傳導電子開始主導而電阻上升趨勢轉趨於平緩。在霍爾效應中看到低溫至高溫由p-type轉n-type，並且其變化溫度和硒元素摻雜有直接關聯。高溫的n-type載子歸咎於於能隙間的Donor Level受熱後激發電子至傳導帶，最後取代原有的電洞使材料變成n-type。透過阿瑞尼士方程式，可由電阻對溫度曲線計算其活化能，同時可以了解低溫下電阻反曲及載子型態改變之間的關係。我們在磁阻量測中觀察到了弱反局域效應，並且從2 K的數據中顯示此現象和硒元素的摻雜沒有直接關聯性。
3D Topological insulator (TI), a type of material that insulates inside bulk and conducts on the surfaces, becomes a popular topic in recent years. The unique topologically protected surface states turn topological insulator to be a potential spintronic material. Bi2Te3 based materials have been studied and identified as topological insulators. In order to study the properties of the surface states, a series of specimens of Bi1.5Sb0.5Te3-ySey (BSTS) with y=1.1, 1.2, 1.4, and 1.6 were fabricated for tuning the band gap around Dirac cone. The lattice structure of Bi1.5Sb0.5Te3-ySey is confirmed to be rhombohedral. For the specimen y=1.4 the lattice constants a ̂ and c ̂are 4.25Å and 29.80Å respectively. The lattice constants decrease with Se substitution increase. To characterize the TI properties, the resistivity, magnetoresistance and Hall effect were studied. Resistivity showed an insulator behavior at high temperatures and surface conduction behavior at low temperatures. The dominate carriers are p-type at low temperatures and become n-type at high temperatures. According to the correlations of resistivity and Hall effect of Bi1.5Sb0.5Te3-ySey, we observed that thermal activation can be tuned by Selenium dopants. The weak anti-localization was also observed in our bulk samples. From the 2 K magnetoresistance, we observed that weak anti-localization was independent on Selenium and Tellurium concentrations in all specimens.參考文獻 [1] L. Fu, C. L. Kane, and E. J. Mele, Phys. Rev. Lett. 98, 106803 (2007)[2] Z. Ren, A. A. Taskin, S. Sasaki, K. Segawa, and Y. Ando, Phys. Rev. B 82, 241306 (2010)[3] J. S. Thakur, R. Naik, V. M. Naik, D. Haddad, G. W. Auner, J. Appl. Phys. 99, 023504 (2006)[4] S. Sangiao, N. Marcano, J. Fan, L. Morellón, Europhys. Lett. 95, 37002 (2011)[5] H. -T. He, G. Wang, T. Zhang, I. -K. Sou, G. K. L. Wong, Phys. Rev. Lett. 106, 166805 (2011)[6] H. T. He, B. K. Li, H. C. Liu, X. Guo, Z. Y. Wang, Appl. Phys. Lett. 100, 032105 (2012)[7] Y. S. Kim, M. Brahlek, N. Bansal, E. Edrey, G. A. Kapilevich, Phys. Rev. B 84, 073109 (2011)[8] Z. Ren, A. A. Taskin, S. Sasaki, K. Segawa, and Y. Ando, Phys. Rev. B 84, 165311 (2011)[9] D. Hsieh, D. Qian, L. Wray, Y. Xia, Y. S. Hor, R. J. Cava, Nature (London) 452, 970 (2008)[10] L. Fu and C. L. Kane, Phys. Rev. B 76, 045302 (2007)[11] M. Z. Hasan*, C. L. Kane†, Rev. Mod. Phys, Volume 82, October-December (2010)[12] H. B. Zhang, H. L. Yu, D. H. Bao, S. W. Li, C. X. Wang , Phys. Rev. B 86, 075102 (2012) 描述 碩士
國立政治大學
應用物理研究所
100755011
101資料來源 http://thesis.lib.nccu.edu.tw/record/#G0100755011 資料類型 thesis dc.contributor.advisor 陳洋元 zh_TW dc.contributor.advisor Chen, Yang Yuan en_US dc.contributor.author (作者) 王冠淵 zh_TW dc.contributor.author (作者) Wang, Kuan Yuan en_US dc.creator (作者) 王冠淵 zh_TW dc.creator (作者) Wang, Kuan Yuan en_US dc.date (日期) 2012 en_US dc.date.accessioned 2-九月-2013 16:56:56 (UTC+8) - dc.date.available 2-九月-2013 16:56:56 (UTC+8) - dc.date.issued (上傳時間) 2-九月-2013 16:56:56 (UTC+8) - dc.identifier (其他 識別碼) G0100755011 en_US dc.identifier.uri (URI) http://nccur.lib.nccu.edu.tw/handle/140.119/59449 - dc.description (描述) 碩士 zh_TW dc.description (描述) 國立政治大學 zh_TW dc.description (描述) 應用物理研究所 zh_TW dc.description (描述) 100755011 zh_TW dc.description (描述) 101 zh_TW dc.description.abstract (摘要) 三維拓樸絕緣體，其擁有表面可以導電但內部卻屬於絕緣體的特殊性質；近年來成為熱門的研究領域。拓樸保護表面態此種獨特性質使得拓樸絕緣體有潛力成為自旋電子學研究材料。在已發表的文獻中可以得知Bi2Te3系列材料已經被證實為拓樸絕緣體。我們製作了一系列的Bi1.5Sb0.5Te3-ySey材料，希望藉由硒元素的摻雜改變在狄拉克錐體附近的能帶結構以更詳加了解拓樸絕緣體表面性質以及其物理特性。他們的晶格結構為菱形六角面體；當摻雜量y=1.6時，a軸及c軸的晶格常數分別為4.25 Å以及29.80 Å；同時也發現晶格常數隨著硒元素的摻雜量提高而逐漸遞減。為了更進一步了解拓樸絕緣體物理性質，我們做了電阻率、磁阻以及霍爾效應的量測以及分析。電阻率的結果顯示，樣品在高溫時呈現絕緣體的電阻性質，但在低溫時表面態傳導電子開始主導而電阻上升趨勢轉趨於平緩。在霍爾效應中看到低溫至高溫由p-type轉n-type，並且其變化溫度和硒元素摻雜有直接關聯。高溫的n-type載子歸咎於於能隙間的Donor Level受熱後激發電子至傳導帶，最後取代原有的電洞使材料變成n-type。透過阿瑞尼士方程式，可由電阻對溫度曲線計算其活化能，同時可以了解低溫下電阻反曲及載子型態改變之間的關係。我們在磁阻量測中觀察到了弱反局域效應，並且從2 K的數據中顯示此現象和硒元素的摻雜沒有直接關聯性。 zh_TW dc.description.abstract (摘要) 3D Topological insulator (TI), a type of material that insulates inside bulk and conducts on the surfaces, becomes a popular topic in recent years. The unique topologically protected surface states turn topological insulator to be a potential spintronic material. Bi2Te3 based materials have been studied and identified as topological insulators. In order to study the properties of the surface states, a series of specimens of Bi1.5Sb0.5Te3-ySey (BSTS) with y=1.1, 1.2, 1.4, and 1.6 were fabricated for tuning the band gap around Dirac cone. The lattice structure of Bi1.5Sb0.5Te3-ySey is confirmed to be rhombohedral. For the specimen y=1.4 the lattice constants a ̂ and c ̂are 4.25Å and 29.80Å respectively. The lattice constants decrease with Se substitution increase. To characterize the TI properties, the resistivity, magnetoresistance and Hall effect were studied. Resistivity showed an insulator behavior at high temperatures and surface conduction behavior at low temperatures. The dominate carriers are p-type at low temperatures and become n-type at high temperatures. According to the correlations of resistivity and Hall effect of Bi1.5Sb0.5Te3-ySey, we observed that thermal activation can be tuned by Selenium dopants. The weak anti-localization was also observed in our bulk samples. From the 2 K magnetoresistance, we observed that weak anti-localization was independent on Selenium and Tellurium concentrations in all specimens. en_US dc.description.tableofcontents Abstract I摘要 IIContents IIIFigure of contents IVTable of contents VChapter 1 Introduction 11.1 Topological Insulator 11.1.1 2D Topological insulator & Quantum hall state 31.1.2 3D Topological Insulator 71.2 Weak Anti Localization 81.3 Seebeck Effect 9Chapter 2 Experimental Techniques 102.1 Equipment & Nomenclature 102.2 Bulk Fabrication 112.3 X-ray Diffraction 142.4 Physical property measurement system 152.4.1 Resistivity 162.4.2 Magneto-resistance 182.4.3 Hall Effect 192.6 Composition Analysis 222.6.1 X-ray Florence 222.6.2 Energy Dispersive Spectrometer 222.7 Seebeck coefficient measurement 24Chapter 3 Experimental Results 253.1 Composition Analysis 253.1.1 XRF & EDS 253.1.2 X-Ray Diffraction 273.1.3 Refinement 313.2 Resistivity 353.3 Hall measurement 393.4 Magneto-resistance 46Chapter 4 Conclusion and Discussion 49Reference 51 zh_TW dc.format.extent 5452567 bytes - dc.format.mimetype application/pdf - dc.language.iso en_US - dc.source.uri (資料來源) http://thesis.lib.nccu.edu.tw/record/#G0100755011 en_US dc.subject (關鍵詞) 拓樸絕緣體 zh_TW dc.subject (關鍵詞) Topological Insulator en_US dc.title (題名) 鉍銻碲硒系列拓樸絕緣體長成與物理特性之研究 zh_TW dc.title (題名) Synthesis and Characterization of Topological Insulator Bi1.5Sb0.5Te3-ySey , y=1.1, 1.2, 1.4 and 1.6 en_US dc.type (資料類型) thesis en dc.relation.reference (參考文獻) [1] L. Fu, C. L. Kane, and E. J. Mele, Phys. Rev. Lett. 98, 106803 (2007)[2] Z. Ren, A. A. Taskin, S. Sasaki, K. Segawa, and Y. Ando, Phys. Rev. B 82, 241306 (2010)[3] J. S. Thakur, R. Naik, V. M. Naik, D. Haddad, G. W. Auner, J. Appl. Phys. 99, 023504 (2006)[4] S. Sangiao, N. Marcano, J. Fan, L. Morellón, Europhys. Lett. 95, 37002 (2011)[5] H. -T. He, G. Wang, T. Zhang, I. -K. Sou, G. K. L. Wong, Phys. Rev. Lett. 106, 166805 (2011)[6] H. T. He, B. K. Li, H. C. Liu, X. Guo, Z. Y. Wang, Appl. Phys. Lett. 100, 032105 (2012)[7] Y. S. Kim, M. Brahlek, N. Bansal, E. Edrey, G. A. Kapilevich, Phys. Rev. B 84, 073109 (2011)[8] Z. Ren, A. A. Taskin, S. Sasaki, K. Segawa, and Y. Ando, Phys. Rev. B 84, 165311 (2011)[9] D. Hsieh, D. Qian, L. Wray, Y. Xia, Y. S. Hor, R. J. Cava, Nature (London) 452, 970 (2008)[10] L. Fu and C. L. Kane, Phys. Rev. B 76, 045302 (2007)[11] M. Z. Hasan*, C. L. Kane†, Rev. Mod. Phys, Volume 82, October-December (2010)[12] H. B. Zhang, H. L. Yu, D. H. Bao, S. W. Li, C. X. Wang , Phys. Rev. B 86, 075102 (2012) zh_TW
