請用此 Handle URI 來引用此文件:
http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/74957
標題: | 碳化矽及低維度材料特性之光學分析技術研究 The Study of Optical Characterization Techniques on Silicon Carbide and Low-dimensional Materials |
作者: | Shee-Min Tan 鄧思敏 |
指導教授: | 陳學禮(Hsuen-Li Chen) |
關鍵字: | 碳化矽,矽空缺,高純度半絕緣碳化矽,零聲子線,光學特性,溫度效應,聲學聲子,空缺穩定性,生物相容測試,毒性檢測, silicon carbide,silicon vacancy,high-purity semi-insulating silicon carbide,zero phonon line,optical characterization,temperature effect,acoustic phonon,vacancy stability,bio-compatibility,toxicity, |
出版年 : | 2019 |
學位: | 碩士 |
摘要: | 碳化矽 (Silicon carbide, SiC) 由於其寬能隙、高電阻率和高導電性而被研究用於下一代半導體,這些特性使其適合用於高功率,高頻率或極端溫度工作環境下。因這些需求需高品質與高電阻率的晶片,因此碳化矽的製程與建立其檢測方法同樣重要。在所有晶體形態中,4H-SiC由於其能隙最寬、原生載子濃度較低,因此較廣泛地被研究作高純度半絕緣(high-purity semi-insulating, HPSI) 半導體材料。在本論文中,我們通過量測SiC的拉曼光譜,利用SiC的光學特性計算載子濃度並推算出理論值的電阻值。此方法能夠突破傳統上量測電阻值的限制,以非接觸式的量測與估算SiC淺層的的片電阻值。接著利用光致發光譜 (Photoluminescence, PL spectra)發現SiC中的矽空缺 (Silicon Vacancy, VSi) 是不可避免的並且會直接影響電阻率, 進而可能造成低估了SiC的載子濃度。
其次,我們研究了VSi的零聲子線 (Zero Phonon Line, ZPL) 對溫度的光致發光譜 (Photoluminescence, PL spectra),從中我們了解到了其缺陷來源和放光機制。我們更進一步研究HPSI-SiC裡VSi的ZPL與電阻率的關係。隨後,我們探討HPSI-SiC在83K以上的溫度、且因低載子濃度而造成較少電子-聲子相互作用的情況下討論ZPL的極化。進一步結果發現,於橫截面的試片其成長方向 (C軸) 垂直於電場 (Electric field, E-field),通過減少聲學聲子與電子之間的耦合來觀察ZPL。最後依據結果我們推測2B1(TA) 聲學聲子的振盪模態會干擾ZPL的出現。 SiC除了應用在半導體產業之外,本論文也研究VSi用於生醫檢測的可能性。因VSi的放光波段在近紅外光 (800~1000 nm)的範圍內,因此能更好的穿透皮膚,而利於開發成生物標記。首先我們探討溫度對於缺陷的穩定性,利用拉曼光譜儀測量碳化矽粒子(Silicon carbide particle, SiCP)再通過升溫,計算並求出其原位溫度。結果表明,VSi可以維持在近700℃並且保留其放光特性。接著,我們也對SiC粒子進行了生物相容性的測試,以測試其對生物體的毒性。在初步的實驗結果中發現碳化矽粒子對健康細胞完全無害。 關鍵字:碳化矽、矽空缺、高純度半絕緣碳化矽、零聲子線、光學特性、溫度效應、聲學聲子、空缺穩定性、生物相容測試、毒性檢測 Silicon Carbide (SiC) has been studied for the next generation semiconductor materials due to its wide bandgap, high resistivity, and high conductivity which make it suitable for working under high power, high frequency, and high temperature environments. Because of those requirements, growing the high quality and high resistivity SiC is in immediate need corresponding along with the efficient inspection methods. Within all polytypes, 4H-SiC has been studied the most for developing into high-purity semi-insulating (HPSI) semiconductor materials due to its widest bandgap and lowest intrinsic carrier concentration. In this thesis, we discussed the optical inspection on SiC with Raman spectra and used the optical characterization of SiC in Raman spectra to calculate the theoretical carrier concentration and estimate the resistivity. Thus, provided an alternative method to estimate the resistivity with no direct contact to samples and overcome the limitation of conventional resistivity measurement. Moreover, we found that the silicon vacancy (VSi) in SiC was inevitable and would affect the resistivity and underestimated the carrier concentration of SiC. Secondly, we studied the Zero Phonon Lines (ZPLs) of VSi with temperature dependence Photoluminescence (PL) spectra which gave us the understanding of the origin and the PL mechanism of VSi. Based on the measured spectra, we discovered that ZPLs could further disclose that the ZPLs of VSi were related to the carrier concentration in HPSI-SiC. Subsequently, we introduced the polarization of ZPLs above 83K yet the electron-phonon interaction was low under the temperatures because of the low carrier concentration in HPSI-SiC. Moreover, the E-field of excitation light perpendicular to the growth direction (C-axis) of cross-section samples could maximize the peak intensity of ZPLs because of reducing the coupling of the acoustic phonon with electrons. Furthermore, we suggest that the 2B1(TA) phonon mode would hinder on the emerging of ZPLs. Furthermore, we suggest that SiC can also be explored for bio applications with its stable PL emission in near-infrared (NIR) regime. The emission of VSi could be useful for bio-marker since it had an emission in the range of NIR (800~1000 nm) and had a better penetration through human skin. For testing the defect stability, we first demonstrated a method by increasing the temperature meanwhile measuring the Raman spectra. After calculating the in-situ temperature of silicon carbide particle (SiCP) from the Raman shift, we showed that VSi could hold up to nearly 700℃ yet still reserving its emission. Moreover, we performed a bio-compatibility test on SiCP for testing the toxicity of SiCP on the living organism. The preliminary result showed the SiCP was harmless to healthy cell. Keywords: silicon carbide, silicon vacancy, high-purity semi-insulating silicon carbide, zero phonon line, optical characterization, temperature effect, acoustic phonon, vacancy stability, bio-compatibility, toxicity |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/74957 |
DOI: | 10.6342/NTU201904112 |
全文授權: | 有償授權 |
顯示於系所單位: | 材料科學與工程學系 |
文件中的檔案:
檔案 | 大小 | 格式 | |
---|---|---|---|
ntu-108-1.pdf 目前未授權公開取用 | 5.23 MB | Adobe PDF |
系統中的文件,除了特別指名其著作權條款之外,均受到著作權保護,並且保留所有的權利。