X-ray diffraction analysis of the defect structure in Al _xGa _1-xN films grown by metalorganic chemical vapor deposition

The reduction of the defects in Al _xGa _1-xN films by increasing Al content was investigated. The films of 1 μm thickness were grown by metal organic chemical vapor deposition (MOCVD) on sapphire (0001) substrates with 20 nm low temperature GaN buffer layers. The grain size was calculated by using x-ray diffraction analysis, and the metal organic sources were trimethygallium (TMGa) and trimethylaluminum (TMAl). The results show that the dislocation density decreases with increasing Al contents up to 0.2.