Microstructure of thick AlN grown on sapphire by high‐temperature MOVPE

Thick AlN layers with atomically flat surfaces were successfully grown directly on sapphire substrates by metal‐organic vapor phase epitaxy at high temperatures between 1300 °C and 1600 °C. Dislocations such as those of the edge, screw and mixed types exhibited different behaviors in the AlN epilayers. The dislocation density of AlN was less than 2 × 109 cm–2. Free and bound excitons of AlN were observed with peak energies of 6.084 eV and 6.063 eV, respectively. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)