Synthesis and optical characterization of single-crystalline AlN nanosheets

Uniform and smooth AlN nanosheets were fabricated on Si substrates by a vapour-phase transport method, using Al powder and ammonia as the source materials. Their morphology and structure were examined by scanning and transmission electron microscopy, and X-ray diffraction. They have a perfect rectangular shape. The growth is favoured along the 〈11̄00〉 and 〈0001〉〈0001〉 crystallographic directions within the 〈112̄0〉 plane. Their growth mechanism is discussed on the basis of data gathered. The linewidth of E2E2 (high) longitudinal optical phonon mode is about 7 cm−1, indicating their high quality. Their photoluminescence property is also investigated.