Abinitiopseudopotential study of structural and high-pressure properties of SiC

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Abstract
An ab initio pseudopotential method is used to study the structural properties of SiC at low and high pressures. For cubic SiC, the calculated ground-state properties, such as the equilibrium lattice constant, bulk modulus, and cohesive energy, are in good agreement with experiment. The indirect band gap of cubic SiC is predicted to decrease with increasing pressure; this behavior is similar to Si but not to C. To study the structural phase stability at high pressures, the rocksalt and tetragonal β-Sn phases are considered. Our calculations suggest that the zinc-blende structure of SiC transforms into the rocksalt phase under a hydrostatic pressure of 660±50 kbar. The calculated value should be regarded as an upper bound for the pressure of a structural phase transition from the zinc blende. The valence-charge distribution for cubic SiC resembles those for other zinc-blende semiconductors.