Epitaxial lateral overgrowth (ELO) of high-quality AlN layers on trench-patterned AlN underlying layers has been demonstrated by high-temperature metal-organic vapor phase epitaxy. Under optimized conditions, a high growth rate and an atomically flat surface of thick ELO-AlN without cracks were obtained. Fully coalesced ELO-AlN epilayers were obtained on AlN templates having (10 (1) over bar0) trenches. AlN grown above the groove had low dislocation density due to filtration caused by the grooves. In addition, most of the dislocations threading from the AlN template were annihilated by the formation of a loop structure during growth with increasing thickness of AlN. The average dislocation density of the ELO-AlN was calculated to be 4 x 10(7) cm(-2). (c) 2006 Elsevier B.V. All rights reserved.