PERMANENT DIPOLE CONTRIBUTION TO THE LINEAR ELECTROOPTIC EFFECT AND VALENCE-BAND DISPERSION IN ZINCBLENDE SEMICONDUCTORS

We show theoretically that the built-in permanent dipole moment of pol ar tetragonal bonds in zincblende semiconductors plays an important ro le in their near-band-gap electro-optic properties. When an external f ield is applied, permanent dipoles cause the anisotropy of the band st ructure in the vicinity of the Gamma point and, consequently, the anis otropy of optical properties near the band edge, whose magnitude we es timate here. [S0031-9007(98)07501-2].