The growth of AlN thin films on (00▪1) sapphire by metal-organic chemical vapor-phase epitaxy was investigated 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 109/cm2 for a 2.1μm thick film compared to partially coalesced 1.05μm films exhibiting a threading dislocation density of 1.1 x 1010/cm2. The reduction in dislocation density resulted from a decrease in the number of edge character threading dislocations, while the screw character density remained virtually unchanged, as determined by X-ray rocking curve measurements of the AlN off-axis (20▪1) and on-axis (00▪2) reflections, respectively. Cross-sectional transmission electron microscopy indicated the presence of a number of inversion domains in the AlN films.

Growth and Laser-Assisted Lift-Off of Low Dislocation Density AlN Thin Films for Deep-UV Light-Emitting Diodes. J.F.Kaeding, Y.Wu, T.Fujii, R.Sharma, P.T.Fini, J.S.Speck, S.Nakamura: Journal of Crystal Growth, 2004, 272[1-4], 257-63