Structural and thermodynamic properties of cubic boron nitride (c-BN) under pressure and for varying temperature are studied by molecular-dynamics (MD) simulation with the use of a well-tested Tersoff potential. Various physical quantities including the thermal expansion coefficient and heat capacity are predicted. Our simulation is extended to study liquid boron nitride at various densities.

First-principles calculations, by means of the full-potential augmented plane wave method using the local density approximation, were carried out for the structural and electronic properties of the Al x Ga 1−x N, In x Ga 1−x N and In x Al 1−x N alloys in the wurtzite structure. We have investigated the lattice parameters and band gap energies. The lattice constants a and c are found to change linearly for the Al x Ga 1−x N alloy, while for both In x Ga 1−x N and In x Al 1−x N alloys the lattice parameters, a, exhibit an upward bowing. The calculated band gap variation for the three alloys exhibit a downward bowing of 0.71 eV, 1.7 eV and 4.09 eV for Al x Ga 1−x N, In x Ga 1−x N and In x Al 1−x N, respectively.

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