Lattice-matched interface between GaN and ZrB2

We present first-principles calculations for the atomic and electronic structure of GaN/ZrB2 interfaces to provide microscopic information on GaN epitaxy on ZrB2 substrates. Both GaN epilayer and ZrB2 substrate almost maintain the bulk structures when the epitaxial growth begins with the formation of N-Zr bonds. On the other hand, a remarkable zigzag structural change, which seems to deteriorate the lattice-matched nature of ZrB2 substrates, is found in the interfacial B-plane when B-N bond formation occurs at the interface. These results indicate that suppression of B-N bond formation is a key point for the effective use of ZrB2 as a substrate of GaN. We also estimate the Schottky barrier heights of these interfaces. For the interface, which contains three N-Zr bonds, the calculated p-type Schottky barrier height is small enough to form ohmic contacts. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim