Epitaxial growth of AlN films on Si substrates by ECR plasma assisted MOCVD under controlled plasma conditions in afterglow region

Wurtzite-type aluminum nitride h-AlN.films were epitaxially grown on off-axis Si 111.substrates by electron– cyclotron–resonance plasma-enhanced metalorganic chemical vapor deposition ECRMOCVD.using trimethylalminum TMA.and ammonia NH3.as source gases. Plasma space potential in the growth chamber was lowered by setting the magnetic field distribution as a mirror field. For the growth of h-AlN with excellent crystallinity on Si substrates, nitridation of the substrate surface, growth of a low-temperature LT.buffer layer, and epitaxial growth of AlN films were performed under a mirror field condition in a growth chamber. Thermal nitridation at 10508C prior to the epitaxial growth appreciably improved the crystallinity of AlN films. The growth of buffer layer at temperatures below 6508C was not so effective for the improvement of the crystallinity and crystal orientation of AlN epitaxial layer. The proportion of domain including stacking faults and that whose c-axis was parallel to the substrate surface was very small I 0002.r I 10 – 10.qI 10 – 11..)700., irrespective of the gas feed ratio of N source to Al source NH3rTMA.during the epitaxial growth process. Under a small gas feed ratio NH3rTMA-200., however, the diffraction peak intensities from the non-epitaxial domains became large. q2000 Elsevier Science B.V. All rights reserved