MOVPE growth and high-temperature annealing of (101¯0) AlN layers on (101¯0) sapphire

Heteroepitaxial growth of AlN layers on (101¯0) m-plane sapphire substrates was investigated by metalorganic vapour phase epitaxy. Different nucleation temperatures were used to achieve single phase (101¯0) AlN layers. The crystallinity of the layers further increased with increasing annealing temperature and annealing time. The full-width at half maximum of the symmetric (101¯0) X-ray rocking curves decreased from about 2900/1940 arcsec to 1030/800 arcsec along [0001]/[112¯0]AlN. The density of basal stacking faults of the annealed layers was found to decrease from ∼2.8 × 105 to ∼1.5 × 104 cm−1. The annealed layers had a larger effective optical bandgap energy of ∼6.15 eV than ∼6.04 eV of the as-grown layers due to their better crystallinity and structural order.