We proposed the heteroepitaxial lateral overgrowth technique using grooved sapphire (0 0 0 1) and (1 12 0) SiC( 0 0 1)(si) and Si(1 1 1) substrates to prepare AlxGa1-xN single crystalline films with low dislocation density. Straight grooves of these substrates were aligned parallel to the < 1 (1) over bar 0 0 > or < 1 1 (2) over bar 0 > direction of AlxGa1-xN. In this technique, neither a selective growth mask nor patterned GaN single crystal film was used. Dislocation densities lower than about 10(6) cm(-2) were ascertained via plan-view TEM. This technique is promising for growing low-dislocation-density nitride-based semiconductors. (C) 2002 Elsevier Science B.V. All rights reserved.