Role of 3C-SiC intermediate layers for III-nitride crystal growth on Si

The role of 3C-SiC intermediate layers in III-nitride crystal growth has been studied by observing III-nitride epilayers grown on Si substrates. We found that better quality epilayers were obtained by using such intermediate layers than by direct growth on Si substrates. In the case of III-nitride epilayers grown directly on Si, the layers grown at the initial stage are not flat. High-resolution transmission electron microscopy observations showed that a non-crystalline layer exists at the interface between the AlN layer and the Si substrate. Thus, the initial growth of III-nitride becomes disordered. On the other hand, the interface between 3C-SiC and the AlN layer is atomically flat, and there is no non-crystalline layer present. We concluded that III-nitride epilayers on Si substrates with 3C-SiC intermediate layers are promising for the fabrication of vertical devices.