- 學位論文
錳摻雜氮化銦薄膜磁各向異性與結構之分析
Analysis of magnetic anisotropies and structural properties of Mn-implanted InN thin film
摘要
本篇研究主要探討錳離子參雜濃度對氮化銦薄膜結構與磁各向異性的影響。 我們利用離子佈植方式參雜氮化銦薄膜研製成氮化銦錳薄膜，離子佈植劑量分別為1*1016cm-2 與8*1016cm-2。X光繞射儀(X-ray diffractionmeter,XRD)分析顯示氮化銦錳薄膜為c軸取向之烏采結構，由能量散佈能譜儀(EDX)半定量分析得知氮化銦錳薄膜之錳離子濃度分別約為0.1 at.%與1 at.%。 藉由超導量子干涉儀(SQUID)量測樣品的變溫磁化強度M可以得到隨溫度變化之關係曲線函數M(T)。我們以外加磁場B平行樣品c軸與垂直樣品c軸兩種量測模式分析，探討樣品正常態與超導態之磁各向異性；另外藉由零場冷卻(ZFC, zero field cooling)以及場冷卻(FC, field cooling)模式定性分析樣品超導態之磁通釘紮能力。我們得到以下之結論: 1.低錳離子濃度之氮化銦錳薄膜在3 K出現超導相變;高錳離子濃度之薄膜則出 現在2.8 K，其超導為第二類超導體; 各向異性參數(γ= )分析顯示高錳離子 濃度之薄膜各向異性參數(γ=3.2)大於低錳離子濃度之樣品(γ=2.9)。外加磁場B 平行樣品c軸之磁通釘紮能力，大於B垂直樣品c軸。 2.氮化銦錳薄膜正常態溫度區間之變溫磁化強度M(T)曲線函數可以朗之凡反磁 性(-Mo)與居里-魏斯定律擬合之。居里常數C值表示樣品具有之順磁磁矩之大小，高參雜之氮化銦薄膜有較大之C值。各向異性參數(γ= )分析顯示高錳離子濃度之薄膜各向異性參數(γ=1.68)，大於低錳離子濃度之樣品(γ=1.09)。
並列摘要
InN thin films irradiated by Mn ion with different concentration were investigated here. InN thin films were grown on sapphire substrate with a 1.5 μm GaN buffer by molecular beam epitaxy (MBE). Mn ions were implanted in InN thin films with doses of 1*1016 cm-2 and 8*1016 cm-2 respectively. The room-temperature Hall mobility and carrier concentration were determined by Hall measurement with Van der Pauw geometry. The atomic percentage of Mn in InN increases with the dose concentration. The percentages were 0.1 at.% and 1 at. % espectively by EDX measurements. Magnetic properties and Superconductivity Meissner effect have been measured by Superconducting quantum interference device (SQUID) measurements. Anisotropic properties were characterized by the applied magnetic field parallel and vertical to the c-axis of InN thin films. The properties of flux pinning in mixed state were characterized by zero field cooling (ZFC) and field cooling (FC) methods. Our results show that InN:Mn(0.1 at.% ) thin films shows superconductivity at 3K and InN:Mn(1 at.% ) thin films shows superconductivity at 2.8K with type II characteristics. The anisotropic parameters are 3.2 and 2.9 respectively. When the applied magnetic field parallel the c-axis of InN thin films, there are larger flux pinning effect. The temperature-dependent magnetization curve in normal state can be fitted by Curie-Weiss Law and Langevin diamagnetic component. InN:Mn(1 at.% ) thin films show larger Curie constant than InN:Mn(0.1 at.% ). The anisotropic parameters of InN:Mn(1 at.% ) thin film is 1.68 and that of InN:Mn(0.1 at.% ) is 1.09 respectively.