Interface stabilization by Al in GaN and AlN epitaxies on Nb B 2(0001)

Abstract

Plasma-assisted molecular beam epitaxy of GaN and AlN is investigated on a boron-terminated transition-metal diboride (0001) surface: Nb B2 (0001). In contrast to metal-terminated Zr B2 (0001), GaN does not grow epitaxially on this surface. Instead, a thin hBN layer is formed. On the other hand, AlN does grow epitaxially on this boron-terminated surface. Moreover, only a monolayer of predeposited Al effectively changes the hBN formation into the GaN epitaxial growth. Such a thin Al-related interface species cannot function as a physical buffer layer to relax the lattice stress, but it does give a chemical effect that lowers the nitride-boride interface energy. © 2006 American Institute of Physics.