Investigation of AlN growth on sapphire substrates in a horizontal MOVPE reactor

AlN growth was performed on c-plane sapphire substrates by metalorganic vapor phase epitaxy (MOVPE) using trimethylaluminium (TMAl) and ammonia. The influence of the carrier gases H2 and N2 and their mixtures on the surface morphology and structural characteristics was investigated as well as the influence of the growth temperature of the total source partial pressure and of the TMAl substrate pretreatment. It was found that smoother layers and better structural characteristics are obtained for lower source partial pressures. Decreasing of growth temperature led to improvement of surface morphology, and increasing of nitrogen in gas phase led to improvement structural quality of the layer. A pretreatment of the substrate leads to rougher layers.