High quality AlN film grown on a nano-concave-circle patterned Si substrate with an AlN seed layer

We have investigated the growth of AlN films on hexagonal nano-concave-circle patterned Si substrates using metal–organic chemical vapor deposition. By depositing a thin AlN seed layer on the Si substrate before the pattern process, a high quality AlN film with a thickness of 2 μm has been obtained. The full width at half maximum values of X-ray diffraction rocking curves are as low as 409 and 677 arc sec for AlN (002) and (102) planes, respectively. Further experimental results indicate that the AlN seed layer can suppress the misorientation of the adjacent grains, as revealed by the lower twist and tilt angles of the mosaic structure, and thus only a few dislocations generated during the grain coalescence. In addition, the migration of Al adatoms is enhanced on the Al terminated surface of the AlN seed layer, which accelerates the coalescence process. All these improvements are attributed to the lower binding energy and diffusion barrier for Al adatoms on the Al terminated surface than that on the Si surface. Our results demonstrate an effective approach to obtain high quality AlN films for high performance ultraviolet light-emitting diodes on the Si substrate.