- 學位論文
鎳鐵 / 氧化鋅複合薄膜之結構、磁、光、介電性質研究
Study of structural, magnetic, optical and dielectric properties of NiFe / Zinc Oxide multilayer thin films
摘要
本研究是利用濺鍍法(Sputtering)，以氬電漿轟擊氧化鋅和鎳鐵靶材，在Si(100),SiO2(100),PET與玻璃基板上製備氧化鋅/ 鎳鐵/ 氧化鋅複合薄膜結構。在本研究中，製備氧化鋅/ 鎳鐵/ 氧化鋅複合薄膜結構，整個過程分為三大部分，其中改變其鎳鐵中間層厚度分析其薄膜微結構、表面形貌、磁性質、光學性質極介電性質。本論文第一部分探討鎳鐵、氧化鋅個別薄膜性質利用操控射頻(RF)功率(75W~200 W)與製程壓力(1×10-2Pa)，並探討在不同製程參數下對於形成(0002)織構的氧化鋅薄膜之影響。由實驗結果顯示：於製程壓力1×10-2Pa、RF功率125W、所沉積之氧化鋅薄膜有較佳之c軸(0002)織構能力，並具有優異的紫外光發光效率。另外隨RF功率增加時，從光致螢光光譜儀(Photoluminescence Spectrophotometer, PL)分析得知有明顯的紅移(Red shift)。第二部分製備氧化鋅/ 鎳鐵/ 氧化鋅複合薄膜結構，隨著中間層鎳鐵薄膜厚度增加，其氧化鋅薄膜內部缺陷增加，造成更明顯的紅移現象，此複合薄膜材料的介電常數大小與中間層鎳鐵層的厚度關係，在頻率 40Hz到30MHz之間被精密量測。在本研究中，研究資料顯示多層薄膜(氧化鋅/ 鎳鐵/ 氧化鋅)的介電常數大小受奈米尺度鎳鐵層的厚度影響而達到一極值，我們發現奈米級厚度(10~40nm)的鎳鐵層使得氧化鋅/ 鎳鐵/ 氧化鋅的複合薄膜之介電常數達到50。
並列摘要
During the past decade , Zinc Oxide is one of the promising materials because of advantages over other wide bandgap semiconductors such as GaN and SiC.. This paper attempts to investigate the structure, magnetism, optical and dielectric properties of ZnO thin films. The ZnO films were deposited onto Si and glass substrates at room temperature by radio-frequency magnetron sputtering without introducing any oxygen source under different sputtering powers ranging from 75 to 175W (75, 100, 125, 150, 175W) with low Ar working pressure of 1×10-2 Pa. From the x-ray diffraction patterns indicated that the (0002) peak intensity increased with increasing the sputtering power, accompanying the getting higher satellite peak intensity of ZnO(0004). ZnO film exhibits a remarkable near-band-edge emission peak located at around 375 nm with a bandgap of 3.24 eV confirmed by room temperature photoluminescence spectra. It is observe that the value of dielectric constant for ZnO thin film is 11. Subsequently, by constructing ZnO / NiFe / ZnO sandwich structure films, we discussed optical and magnetic properties of NiFe layers, the crystallization of thin films, and its dielectric properties. Also, we compared these NiFe sandwich films with ZnO thin films . By increasing the thicknesses of NiFe layer, we discussed its influence on dielectric properties. It was discovered that by increasing the thickness of NiFe layer, the interface polarization was induced by the thicknesses of NiFe more than 5 nm, and the dielectric constant increased to. Besides, by applying magnetic field to the samples, it was discovered that the changes of the dielectric constant were less than 0.1%.