Electronic structure and total energy of diamond/BeO interfaces

Abstract

Electronic structure calculations are used to study the bonding at diamond/BeO interfaces. The {110} interface between zinc blende BeO and diamond is used as a representative model for general reconstructed interfaces characterized by an equal amount of Be–C and O–C bonds. The interface energy is calculated to be 2 J/m2 and combined with the estimated free surface energies to obtain an estimate of the adhesion energy. It is found to be close to the adhesion of BeO to itself, but somewhat lower than that of diamond to itself. The effects of the 7% lattice mismatch on the total energy and the band structure for a biaxially strained pseudomorphic diamond film are investigated. The effect of misfit dislocations, expected to occur for thicker films, on the adhesion energy is estimated to be lower than 10%. The bulk properties, such as equilibrium lattice constant, bulk modulus, cohesive energy, and band gap of BeO are shown to be in good agreement with experimental values and previous calculations. The valence-band offset is calculated to be 3.9 eV and found to take up most of the large band gap discontinuity. The nature of the bonding is discussed in terms of the local densities of states near the interface. The interface localized features are identified in terms of Be–C and O–C bonding and antibonding states.