氮化銦鎵、氧化鋅和氮化銦薄膜之拉塞福散射分析及其相關研究

Abstract

在本論文中主要在討論拉塞福散射對氮化銦鎵，氧化鋅，氮化銦薄膜之研究及相關分析。由於有相近的晶格及熱擴張系數，氧化鋅被考慮用來當作三族氮化物磊晶成長的基板材料。因此我的工作包含了使用有機金屬化學氣相沈積磊晶技術在晶格匹配的氧化鋅基板上成長氮化鎵磊晶層的分析及研究。然而，在使用有機金屬化學氣相沈積磊晶在氧化鋅上成長氮化鎵仍有數個數個議題待解決。其中一個是氧化鋅基板的熱穩定性，鋅及氧原子擴散到磊晶層板，這會造成氮化銦鎵較不佳的品質。拉塞福背向散射可分析出在氧化鋅上成長的氮化銦鎵及氮化鎵薄膜厚度及組分，此外，還可發現鋅原子的擴散及磊晶層的表面粗度。透過室溫的光激發螢光檢測及二次離子質譜儀縱深剖面能譜，我們可得到樣品的光學及結構特性。我們接下來繼續探討在磊晶時的成長溫度對氮化銦鎵的結晶品質影響，利用拉塞福背向散射得到氮化銦鎵及氮化鎵薄膜厚度及組分，並由分析中可得在磊晶層中較低的成長溫度可得較高的銦含量，此模擬結果同樣在室溫的光激發螢光檢測及拉曼光譜中得到驗證。 氧化鋅是下個世代最熱門的光電材料，有著3.3eV的寬能隙，以及60meV的激子侷限能，加上可以與鎂及鎘共同組成三元或四元化合物，與氮化鎵基的光電材料相類似。我們探討氧化鋅薄膜成長於業界常用的藍寶石基板，由拉塞福背向散射分析我們可得氧化鋅薄膜的厚度及組分；再由室溫的光激發螢光檢測，穿透譜，橢偏儀，進階探討其光學性質。 氮化銦材料擁有0.7電子伏特的直接能隙，被預期能運用在高頻高速的元件和光通訊的材料上。我們利用分子束磊晶來成長氮化銦。其中，電漿槍的瓦數對氮化銦的電性有極大的影響。 另外，從光激發螢光實驗及拉曼光譜可得其光學性質。我們同時也利用拉塞福背向散射分析出在不同的電漿槍強度下的氮化鎵薄膜厚度及組分，並在近一步研究出在較低的電漿強度下可得較均勻的薄膜。

Rutherford Backscattering Spectrometry (RBS) technology was employed to study the structure of nanometer scale InGaN/GaN grown on ZnO substrate. Through penetrating simulation, Zn diffusion from substrate and interlayer diffusion between InGaN/GaN and GaN/ZnO have been clearly revealed and determined quantitatively. The fuzz of InGaN and GaN layers is about 7 nm and the fuzz of GaN and ZnO layers is about 9 nm. InxGa1-xN layers have been grown on ZnO substrates by metalorganic chemical vapor deposition utilizing a low temperature grown thin GaN buffer. InGaN layers were grown at temperatures ranging from 656 to 736°C. Rutherford Backscattering technology was employed to analyze this structure. Through simulation, the detailed information on the grown InGaN layers containing higher In composition in the higher growth temperature is obtained, which are suitable for wide light range InGaN multiple quantum well light emitting diode device applications. A series of ZnO thin films with different thicknesses grown on sapphire substrates by metalorganic chemical vapor deposition (MOCVD) have been studied by different characterization techniques. The optical properties are investigated by photoluminescence (PL), optical transmission (OT) and 1st order derivatives, various angle scanning ellipsometry (VASE). Rutherford Backscattering (RBS) shows the atomic Zn:O ratios with a few percentage aviation from 1:1, and thicknesses in range of 10~230 nm, roughness layer with 10~30nm, which are corresponding to results from atomic force microscopy (AFM), and scanning electron microscopy (SEM). The optical and structure characterization measurements have confirmed the good quality of these epitaxial ZnO materials. We also report the optical properties of a series of InN thin films grown on sapphire substrates via plasma-assisted molecular beam epitaxy (PA-MBE) with different Nitrogen plasma power. It was confirmed that the films quality improved by decreasing the plasma power of Nitrogen. A series of characterization techniques, including Hall, photoluminescence, Rutherford backscattering, Raman scattering, and scanning electron microscopy have been employed to study these InN films. In these experiments, it was obvious that Eg of InN depends on the crystal growth condition of plasma level. The alloy compositions and thickness were accurately determined using Rutherford backscattering spectrometry and it can obtained that the InN film grown under lower plasma power level is shown with better film uniformity.