High-temperature thermal annealing of nonpolar (1 0 [formula omitted] 0) AlN layers sputtered on (1 0 [formula omitted] 0) sapphire.

Thermal annealing at high temperatures of nonpolar (1 0 1 ¯ 0) m -plane AlN layers directly sputtered on m -plane sapphire was investigated. The crystallinity of the layers increased with increasing annealing temperature. The full-width at half maximum of the symmetric (1 0 1 ¯ 0) X-ray rocking curves along [0 0 0 1]/[1 1 2 ¯ 0 ] AlN decreased from about 3.5/2.0 ° to 0.24/0.19 ° . The density of basal stacking faults of the annealed layers was found to decrease from ∼ 1 × 10 5 to ∼ 5 × 10 3  cm −1 . The annealed layers had a larger optical bandgap energy than the as-sputtered layers due to their better crystallinity and structural order. [ABSTRACT FROM AUTHOR]