Crystal Potential and Energy Bands of Semiconductors. II. Self-Consistent Calculations for Cubic Boron Nitride

Abstract

A self-consistent crystal potential is constructed for cubic BN. Exchange is included according to the Slater free-electron approximation. The effect of the heteropolar character of the potential is included explicitly in an approximately self-consistent treatment of the valence-electron charge density. The energy gap is found to be about twice that of diamond, consistent with the results of other zincblende crystals and their diamond-type analogs. The maximum of valence band and the minimum in the conduction band are at the center and (100) face of the Brillouin zone, respectively. It is suggested that the heteropolar potential splits the valence band into two sub-bands. The lower sub-band width is about 5 ev, while the higher (which contain three times as many states) has a band width of about 4 ev. The energy gap between the sub-bands is about 10 ev. The effect should be common to all zincblende crystals and may be observable by soft x-ray emission.