Atomic arrangement at the AlN/Si (111) interface

High-quality GaN epilayers have been grown on Si (111) substrates by metalorganic vapor phase epitaxy using a low-temperature AlN nucleation layer. The atomic arrangement at the epilayer/substrate interface has been investigated by high-resolution electron microscopy. A crystallographically abrupt interface is observed along most of the epilayer, indicating that the AlN/Si interface is thermodynamically stable and of high crystalline quality. Lattice images at the interface show a periodic array of misfit dislocations. The lattice images have been analyzed in detail in order to obtain information about the atomic arrangement, and interface bonding models are proposed.