MBE of AlN on SiC and influence of structural substrate defects on epitaxial growth

Aluminum nitride layers were grown on Si-terminated SIC (0 0 0 1) at variou s substrate temperatures, growth rates, and V/III-ratios in a RF-plasma enh anced MBE system. Surface morphology detected by AFM is strongly influenced by V/III-ratio. Smooth surfaces with a RMS-roughness below 1 nm are obtain ed for stoichiometric growth conditions giving the smallest FWHM of the XRD -rocking curves of 190 arcsec. For the growth of a more rough AlN-surface l ayer (RMS 2-24 nm) atomically smooth areas have been detected around microp ipes by AFM indicating changed growth conditions. Lateral extension of this area is increased by reducing the growth rate or the V/III-ratio. (C) 1999 Published by Elsevier Science B.V. All rights reserved.