Effect of growth temperature of an AlN intermediate layer on the growth mode of AlN grown by MOCVD.

High-temperature AlN (HT-AlN) films inserted with a thin AlN intermediate layer were grown on c-sapphire directly by MOCVD, and the influence of growth temperature of the AlN intermediate layer on the growth mode of HT-AlN was investigated. The results showed that with the temperature of the AlN intermediate layer increasing from 470 to 670 ?C, the growth mode was changed from three-dimensional (3D) growth to two-dimensional (2D) growth. However, when the temperature was further increased to 870 ?C, the growth mode was changed into 3D growth again. This suggested that the thin AlN intermediate layer could alter the growth mode of the HT-AlN film by varying the growth temperature, which provides a possible way to improve the morphology and quality of AlN films. The reasons responsible for this phenomenon were probed by Raman spectral, reciprocal space map and growth evolutions of AlN, and a model was developed to explain the effects of IM-AlN on the growth mode of HT-AlN. [ABSTRACT FROM AUTHOR]