The Effect of Al Interlayers on the Growth of AlN on Si Substrates by Metal Organic Chemical Vapor Deposition

The influence of an Al interlayer on the crystalline quality and surface morphology of AlN epitaxial layers is investigated. 100 nm thick (0002) oriented AlN layers were grown on Si (111) substrates by metal organic chemical vapor deposition. Al interlayers were introduced through Al soaking, followed by nitridation for different lengths of time. When the nitridation time was 0 s, the AlN surface was uneven. At a nitridation time of 15 s, the AlN epilayer started to transform into a smooth surface. When the nitridation time was increased to 40 s, the AlN films had rough surfaces. X-ray diffraction measurements showed that the full width at half maximum of the (0002) peak decreased to 801.9 arcsec by introducing the Al interlayer for a nitridation time of 25 s. The roughness of the AlN surface was reduced from 5.30 nm to 1.91 am compared with the films without an Al interlayer. The Al interlayer improved the crystalline quality and surface roughness of the AlN films. An optimized nitridation time was important in achieving an appropriate surface roughness for high quality crystals of AlN on Si (111) surfaces.