Epitaxial growth mechanisms of AlN on SiC substrates at room temperature

Abstract

Epitaxial AlN films have been grown on atomically flat 6H-SiC (0001) and 4H-SiC (0001) substrates at room temperature (RT), and their growth mechanisms have been investigated. It has been revealed that the growth of AlN at RT proceeds in a layer-by-layer mode from the initial stage. During the growth, AlN nucei have an equilateral triangular shape probably due to the anisotropy in growth rates. The triangular AlN nuclei at the adjacent terraces formed on the 6H-SiC substrates are rotated by 60°, whereas the triangular AlN nuclei on the 4H-SiC were formed in the same direction on all of the terraces. This phenomenon can be explained by the difference in the arrangement of the atoms for the topmost layers.