Trends in band-gap pressure coefficients in boroncompounds BP, BAs, and BSb

Abstract

We have performed an ab initio investigation for a series ofboron compounds, BP, BAs, and BSb, and have compared theirstructural and electronic properties with those of c-BN. Thecalculations are performed using a plane-wave expansion within the localdensity approximation and the pseudopotential approximation.Results are given for lattice constants, bulk moduli, bandstructures, and band-gap pressure coefficients. The electronicproperties of these compounds are shown to have features that differfrom those of other III-V materials. We found that the direct-band-gap pressure coefficient in boron compounds is nearlyindependent of the anion substitutions. As a result, this trend issimilar to the one resulting from cation substitutions in otherzinc-blende compounds. This is another anomalous behaviour whichcan be characterized by reversing the standard assignments for theanion and cation in these compounds.