The measurement of dislocation densities in heteroepitaxial semiconductor GaN film is important for the developement of blue light-emitting diodes, laser diode and high temperature, high-frequency electronic devices. As there is no matching substrate material, GaN thin films prepared by epitaxial growth often contain a large number of defects, most of which are edge dislocations. High resolution X-ray diffraction method and the mosaic model were used to measure and analyze the dislocation density of GaN film fabricated by metal organic chemical vapor deposi-tion (MOCVD) on a 4H-SiC substrate with an AlGaN buffer layer. The crystal face tilting angle, in-plane twisting an-gle, grain size and crystal bending radius were investigated by symmetry and oblique symmetry diffraction methods. By eliminating the instrumental broadening width (mainly the incident beam divergence), grain size and wafer curva-ture influenced on the contribution to the full width at half maximum of rocking curves, Screw dislocation density and edge dislocation density of the GaN film were accurately determined to be 4.62×107 cm-2 and 5.20×109 cm-2, respectively. The total dislocation density was 5.25×109 cm-2. There were less than 1% screw dislocations, and the ratio of mixed to edge dislocation failed to be determined.%利用高分辨 X 射线衍射方法,分析了在4H-SiC(0001)面上采用金属有机物化学气相沉积(MOCVD)生长的GaN 薄膜的位错。采用对称面衍射和斜对称面衍射等方法研究了晶面倾转角、面内扭转角、晶粒尺寸和晶面弯曲半径等参数,通过排除仪器、晶粒尺寸及晶面弯曲对摇摆曲线半高宽的影响,从而获得 GaN 薄膜的螺位错密度和刃位错密度分别为4.62×107cm-2和5.20×109 cm-2,总位错密度为5.25×109 cm-2。
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