本論文主要藉由X-光雙晶繞射曲線(DCXRD)分析及穿透式電子顯微術檢測探討生長於氧化釓/(111)面矽基板上之氮化鎵薄膜內部的缺陷特性。依Pseudo-Voigt 函數概念將DCXRC氮化鎵半高寬(FWHM)值套入以研究基板與薄膜間扭轉(twisting)與傾斜(tilting)作用之關係。並估算出薄膜內各類差排之密度。實驗利用化學蝕刻計算氮化鎵之差排密度，穿透式電子顯微術(TEM)與X光繞射技術(XRD)量測分析，並將量測成果與理論估算值相互比較。氧化釓/矽基板之氮化鎵內部刃差排密度較螺旋差排密度還高。藉由穿透式電子顯微術本研究進一步了解氮化鎵薄膜、矽基板與氧化釓緩衝層間之方位關係，尤其藉由TEM影像消失準則分析可觀察到薄膜內部包括差排之缺陷分布與型態。高解析度穿透式電子顯微分析並發現高晶格錯配致使氮化鎵內部存在大量錯配差排、差排環和疊差等缺陷。 Characteristics of the defects in the GaN film prepared on the Gd2O3-coated (111) Si substrate were studied in this thesis. The line widths of various double-crystal rocking curves were fitted to Pseudo-Voigt function to evaluate twisting and tilting operations between GaN mosaic cells and substrate so that the densities of different kinds of dislocations in the GaN film were calculated. The densities and characteristics of dislocations in the GaN film were evaluated experimentally by etching pit counts, transmission electron microscopy (TEM) and DCXRC measurements. It was found that the density of dislocations having edge-component is larger than that of dislocations having screw component. The orientation relationships between GaN / Gd2O3 and Gd2O3 / (111)Si were also revealed by TEM analyses. Using g‧b=0 invisibility criterion, various types of dislocations in GaN film were further identified. High resolution TEM (HRTEM) observations show the presence of various kinds of atomic-scaled defects in the GaN film including dislocation loop, stacking fault and misfit dislocations.