Structural properties of Si and Mg doped and undoped Al_0.13Ga_0.87N layers grown by metalorganic chemical vapor deposition

Structural properties of Si and Mg doped and undoped Al_0.13Ga_0.87N 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 Al_0.13Ga_0.87N layers rapidly decrease due to the increased island size by surfactant effect. The origin of the broadening of HRXRD rocking curve in Al_0.13Ga_0.87N 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 3.172μmol/min.