Structural properties of Si and Mg doped and undoped Al0.13Ga0.87N layers grown on sapphire substrates by metalorganic chemical vapor deposition were studied using high-resolution X-ray diffraction (HRXRD) and transmission electron microscopy. For both low SiH4 and low Cp2Mg flow rates, the full width at half maximum values of rocking curve and total threading dislocation density in Al0.13Ga0.87N layers rapidly decrease due to the increased island size by surfactant effect. The origin of the broadening of HRXRD rocking curve in Al0.13Ga0.87N layers with high SiH4 and Cp2Mg flow rates results from the increase of total threading dislocation density and stacking fault density, respectively. Beside, it was observed that while for Si doping the lattice constant c is decreased continuously with the SiH4 flow rate, the lattice constant c of Mg doped AlGaN layers is rapidly increased with a Cp2Mg flow rate of 3.172 mu mol/min.