High Resolution X-ray Diffraction Analysis of Defect Density of Gallium Nitride Epitaxial Layer

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 deposition (MOCVD) on a 4H-SiC substrate with an AlGaN buffer layer. The crystal face tilting angle, in-plane twisting angle, grain size and crystal bending radius were investigated by symmetry and oblique symmetry diffraction methods.