- 學位論文
以氮化銦和氮化銦為基礎之薄膜結構及磁性性質分析
Structal and Magnetic Analysis of InN and InN-base thin film
摘要
我們探討表面形貌與離子掺雜，對氮化銦與氮化銦基（InN-based）薄膜結構與磁性之影響。樣品分別為由MBE與MOCVD成長之氮化銦基薄膜結構，XRDθ-2θ的量測結果顯示其為wurtzite結構之高品質結晶薄膜結構。我們藉由超導量子干涉儀（superconductor quantum interference device，SQUID）量測磁性, 並且以掃瞄電子顯微鏡（scanning electron microscope，SEM）與X光電子能譜儀（X-ray photoemission spectroscopy，XPS）分析樣品之表面。 電子能量散佈能譜儀（Electron dispersive spectroscopy，EDS）的分析結果顯示，InN表面以銦離子、氮離子以及氧離子為主，鎂與錳離子掺雜之樣品則分別可看到鎂離子與錳離子的訊號。我們比較不同樣品之In/N/O比例，結果顯示樣品分別有不同之In離子、N離子以及氧離子濃度；濃度不同使得N離子與In離子價數也會改變，我們藉由XPS分析其價數，探討對磁性之影響。 Mg離子掺雜會影響InN磁性，因濃度不同而分別有鐵磁性與超導性之結果。Mn離子掺雜InN之量測結果顯示超導性，詳細之超導相至今未明，這是我們未來的研究方向。 我們的實驗結果說明在釐清氮化銦基薄膜結構的磁性來源時，除了檢測銦離子的價數外，銦離子周圍的局域微結構之探討也是很重要的因素。
並列摘要
We study effects of surfaces and ion doping on the magnetic properties of InN and InN-based thin films. Samples were prepared by MBE and MOCVD respectively. XRDθ-2θscans of InN and InN-based thin films show wurtzite structure indicating good crystalline quality. Magnetic properties were measured by superconductor quantum interference device （SQUID）. Surfaces analysis were performed by scanning electron microscope（SEM）and X-ray photoemission spectroscopy（XPS）, respectively. Electron dispersive spectroscopy（EDS）analysis show that there are Indium、Nitrogen and Oxygen on the surfaces. For the Mg-doped and Mn-doped InN samples, there are Magnesium and Manganese signals respectively. The ratio of In/N/O show there are different In (N) ion concentrations in the samples. Therefore, the charge states of In as well as N are different. The oxidization in InN films were studied by XPS analysis. The observed change on magnetic properties could be related to the variations of the microstructure measuring by XPS. For Mg-doped InN thin films, ferromagnetism and superconductivity were observed with different Mg concentrations. For Mn-doped InN thin film, superconductivity was observed but the origins are still not clear this moment. Our experimental results suggest that both the charge states of In ion as well as the local structure surrounding In ion are important to clarify the origins of magnetic properties of InN and InN-based thin films.