AlGaN/GaN heterostructure grown on 1∘ -tilt sapphire substrate by MOCVD

AlGaN/GaN epitaxial layers were grown on 0∘-tilt and 1∘-tilt sapphire substrates by metalorganic chemical vapor deposition (MOCVD). With exactly the same growth conditions, it was found that dislocation density was smaller and crystal quality was better for the AlGaN/GaN epitaxial layers prepared on 1∘-tilt sapphire substrate. We also found that AlGaN/GaN epitaxial layers on 1∘-tilt sapphire substrate were grown with step growth mode while those on 0∘-tilt substrate were grown with two-dimensional island growth. From the temperature-dependent mobility, it was found that crystal quality of the AlGaN/GaN epitaxial layer prepared on 1∘-tilt sapphire substrate is better.