Microstructure of N-face InN grown on Si (111) by plasma-assisted MBE using a thin GaN–AlN buffer layer

The structural properties of 2 mm thick N-face InN film, grown on Si (111) by plasma source molecular beam epitaxy after the initial deposition of 20 nm AlN and 40 nm GaN, were examined by transmission electron microscopy. The lattice mismatched GaN/AlN and InN/GaN interfaces limited the propagation of threading dislocations (TDs). Dislocation annihilation interactions occurred in the first ~200 nm of the InN film and reduced the TD density. However, the density of screw and mixed type TDs was four times higher than edge type ones. This was attributed to the observed GaN/InN interfacial roughness, which was introduced by terminating TDs from the GaN/AlN buffer layer. Strain measurements showed that the InN film, as well as both buffer layers, was relaxed.