脈衝雷射蒸鍍法製備氧化銪鋅薄膜之探討：結構、光學與磁性研究
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2016
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本論文利用脈衝雷射沉積法在氧氣壓力3×10-1 mbar、溫度750°C環境下，在c方向的藍寶石基板上製備厚度100 nm的氧化銪鋅薄膜，其中銪的原子莫耳濃度介於0~15 %之間、雷射能量密度1.6 J/cm2，檢測氧化銪鋅薄膜的結構、光學以及磁特性。
利用XRD分析樣品成份發現所有實驗比例皆小於配方比例。X光繞射圖譜和拉曼光譜顯示樣品沒有雜晶相產生，隨著Eu摻雜濃度上升樣品粒徑大小減少。純氧化鋅PL光譜只有本質發光，缺陷發光是Eu摻雜造成，為氧間隙、鋅空缺、和氧空缺。而高濃度的氧化銪鋅(8%、10%、15%)樣品多了鋅間隙發光機制。藉由橢圓偏振光譜和穿透光譜發現銪摻雜的比例上升能隙有逐漸變大的趨勢。藉由SQUID量測3 %、5 %、8 %的氧化銪鋅薄膜在室溫及5 K的溫度下表現出順磁性。
Pulsed-laser deposition (PLD) was applied to grow 100 nm thick Europium (Eu)- doped ZnO (Eu:ZnO) thin films on c-sapphire substrate under 3×10-1 mbar of Oxygan. The Eu concentration ranges from 0 to 15 at.%, temperature of substrate is 750°C, and laser fluence is 1.6 J/cm2. The deposition rate, structural properties, optical properties and magnetic properties of Eu:ZnO thin films were investigated in this study. Eu concentrations determined by the X-ray photoelectron spectroscopy (XPS) were slightly smaller than the nominal concentration. X-ray diffraction (XRD) and Raman-scattering spectra revealed Eu incorporation into ZnO without secondary phase. As Eu density increased, the grain size of Eu:ZnO thin films decreased. Photoluminescence (PL) spectroscopy showed that all the thin films had oxygen interstitials , zinc vacancies and oxygen vacancies. In addition, high Eu concentration thin films (8%,10%,15%) had zinc interstitials. By both spectroscopic ellipsometry and optical transmission spectroscopy, the direct band gap of Eu-doped ZnO thin films was found to increase with increasing Eu concentration. At T = 5 K and 300 K ,magnetic investigations with a superconducting quantum interference device(SQUID) magnetometer showed paramagnetism for all Eu-doped ZnO thin films.
Pulsed-laser deposition (PLD) was applied to grow 100 nm thick Europium (Eu)- doped ZnO (Eu:ZnO) thin films on c-sapphire substrate under 3×10-1 mbar of Oxygan. The Eu concentration ranges from 0 to 15 at.%, temperature of substrate is 750°C, and laser fluence is 1.6 J/cm2. The deposition rate, structural properties, optical properties and magnetic properties of Eu:ZnO thin films were investigated in this study. Eu concentrations determined by the X-ray photoelectron spectroscopy (XPS) were slightly smaller than the nominal concentration. X-ray diffraction (XRD) and Raman-scattering spectra revealed Eu incorporation into ZnO without secondary phase. As Eu density increased, the grain size of Eu:ZnO thin films decreased. Photoluminescence (PL) spectroscopy showed that all the thin films had oxygen interstitials , zinc vacancies and oxygen vacancies. In addition, high Eu concentration thin films (8%,10%,15%) had zinc interstitials. By both spectroscopic ellipsometry and optical transmission spectroscopy, the direct band gap of Eu-doped ZnO thin films was found to increase with increasing Eu concentration. At T = 5 K and 300 K ,magnetic investigations with a superconducting quantum interference device(SQUID) magnetometer showed paramagnetism for all Eu-doped ZnO thin films.
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稀磁性半導體, 氧化鋅, 銪, 順磁性, DMS, ZnO, Eu, pulsed-laser deposition