The direct growth technique, using periodically grooved substrates of sapphire(00•1), sapphire(11•0) and 6H-SiC(00•1)Si, was used to grow low dislocation-density AlGaN with AlN molar fractions of below 0.14. The dislocation densities observed in lateral growth areas were of the order of 107/cm2 or less, and similar to those in GaN prepared by using the same technique. It was also found that doping Mg into AlGaN films was very effective in assisting lateral growth, and lateral coalescence was possible within a shorter growth time.

Growth Mechanism and Characterization of Low-Dislocation-Density AlGaN Single Crystals Grown on Periodically Grooved Substrates. T.Detchprohm, S.Sano, S.Mochizuki, S.Kamiyama, H.Amano, I.Akasaki: Physica Status Solidi A, 2001, 188[2], 799-802