Interface characteristics of cubic AlN film on MgO (100) substrate

Highly oriented cubic AlN film was deposited on MgO (100) substrate by laser molecular beam epitaxy (LMBE) technique, and the interface characteristics were investigated. Cubic AlN film and MgO substrate show the well-defined orientation relationship of AlN [001]//MgO [001] and AlN (100)//MgO (100). The AlN/MgO interface is characterized by coherent regions separated by periodically spaced misfit dislocations, forming a semi-coherent interface. The experimentally measured interface dislocation spacing is slightly smaller than that calculated from the lattice mismatch, implying that the lattice mismatch between cubic AlN film and MgO substrate is accommodated mainly by interface misfit dislocations.