溫度與氧壓對氧化鋅摻雜釓的光學性質與磁性影響

Effect of Temperature and Oxygen Pressure on Optical Properties and Magnetic Properties of Zinc Oxide Doped Gadolinium

姚壬茨(Yao Ren-Ci)

指導教授 ： 駱芳鈺

國立臺灣師範大學/理學院/物理學系/碩士(2019年)

https://doi.org/10.6345/NTNU201900940

摘要

本論文利用脈衝雷射蒸鍍法(PLD)在c方向的單晶藍寶石基板上製備150 nm厚的氧化鋅(ZnO)與氧化釓鋅(ZnGdO)，並探討薄膜鍍膜速率、薄膜的結構特性、光學性質及磁性的和基板溫度、鍍膜氧壓關係。薄膜的製備條件PLD單位面積雷射能量為2.5 J/cm2，鍍膜氧壓分別為3×10-1 mbar與3×10-2 mbar，釓的摻雜比例為5 at.%，鍍膜溫度為室溫到750 ℃。
X光繞射及拉曼散射光譜顯示薄膜並沒有雜質或其他晶相產生，表示釓成功的取代氧化鋅。鍍膜溫度在750℃時，薄膜結晶品質最好，其中氧化鋅薄膜的最佳鍍膜氧壓為3×10-1 mbar，氧化釓鋅薄膜的最佳鍍膜氧壓則為3×10-2mbar。在最佳鍍膜條件下，氧化鋅和氧化釓鋅薄膜的晶粒大小分別為31.82 nm、16.87 nm；拉曼光譜也出現E2L-B1H特徵峰。
螢光光譜顯示氧化鋅與氧化釓鋅薄膜皆可觀察到近能隙發光，而氧化鋅薄膜主要來自鋅間隙、鋅空闕的缺陷發光；氧化釓鋅主要來自鋅間隙、鋅空缺和氧空缺的缺陷發光。超導量子干涉磁量儀測量結果顯示氧化鋅薄膜與氧化釓鋅皆為順磁性，飽和磁矩隨著鍍膜溫度下降而上升，有摻雜釓的氧化鋅的磁矩較氧化鋅高。飽和磁矩的來源除了摻雜的釓原子，還包含薄膜中的缺陷，但這些缺陷並沒有辦法增強耦合交互作用，因此雖然摻雜5 %的釓仍為順磁性，沒有變成鐵磁性。

關鍵字

氧化鋅 ； 釓 ； 脈衝雷射蒸鍍 ； 鍍膜氧壓 ； 基板溫度

並列摘要

In this paper, 150 nm thick zin oxide (ZnO) and gadolinium (Gd) doped ZnO (ZnGdO) thin films were prepared by pulse-laser deposition (PLD). For the thin films growth, the laser energy fluence is 2.5 s/cm2, the growth temperatures range between room temperature and 750 ℃, and the oxygen partial pressure are 3×10-1 and 3×10-2 mbar, respectively. The relationship between films deposition rate, structural, optical, and magnetic properties of the thin films versus the growth temperature and oxygen partial pressure were explored.
X-ray diffraction (XRD) and Raman-scattering spectra showed Gd incorporation into ZnO without secondary phase. The best growth temperature is 750 ℃, where the best oxygen partial pressures for ZnO and ZnGdO are 3×10-1 and 3×10-2 mbar, respectively. Under the best growth conditions, the grain sizes for ZnO and ZnGdO are 31.82 nm and 16.87 nm, respectively; the E2L-B1H characteristic peak appears in Raman-scattering spectra.
Near band edge (NBE) emission peaks as well as emission peaks related to zinc vacancy, zinc interstitial are observed in photolumiscence (PL) spectra for both ZnO and ZnGdO thin films. In addition, oxygen vacancy emission peaks are identified for ZnGdO thin films.
Magnetic investigations with a superconducting quantum interference device (SQUID) magnetometer showed that both ZnO and ZnGdO thin films are paramagnetic without long-range ordering. The saturation moment increases as the growth temperature decreases. Both Gd dopant and defects contribute to total magnetic moment, but the defects do not involve in magnetic interaction – therefore, the thin films are paramagnetic.

並列關鍵字

Zin oxide ； gadolinium ； pulsed-laser deposition ； oxygen partial pressure for deposition ； substrate temperature

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