The growth of AlN thin films on (0 0 0 1) sapphire by metal-organic chemical vapor-phase epitaxy has been investigated to serve as the template layer of deep-ultraviolet light-emitting diodes. Delayed coalescence of AlN films resulted in a low threading dislocation density of 5 x 10(9) cm(-2) for a 2.1 mum thick film compared to partially coalesced 1.05 mum films exhibiting a threading dislocation density of 1.1 X 10(10) cm(-2). The reduction in dislocation density results from a decrease in the number of edge character threading dislocations, while the screw character density remains virtually unchanged, as determined by X-ray rocking curve measurements of the AlN off-axis (2 0 11) and on-axis (0 0 0 2) reflections, respectively. Cross-sectional transmission electron microscopy indicates the presence of a number of inversion domains in the AlN films. Electrically injected, 317 nm AlxGa1-xN LEDs were successfully fabricated, with a maximum output power of 17.7 muW tested on wafer at 160 mA DC. Using a 248 nm KrF excimer laser, a 2.8 mum thick AlN film was debonded from the sapphire substrate using a laser pulse power of I J/cm(2). However, substrate debonding of an Al(x)G(a1-x)N/AlN LED layer Could not be achieved. (C) 2004 Published by Elsevier B.V.