PIEZOELECTRIC FIELDS IN ONE-DIMENSIONAL AND 2-DIMENSIONAL HETEROSTRUCTURES FABRICATED ON HIGH-INDEX SURFACES

We present a theoretical study of the strain-induced piezoelectric fie lds which may occur in one- and two-dimensional III-V compound semicon ductor heterostructures on high-index surfaces. The strain tensor comp onents of the low-dimensional structures are calculated by minimizatio n of the strain-energy density and by imposing appropriate constraints at the heterointerfaces. We obtain a tetragonal deformation for two-d imensional heterostructures grown on the high symmetry surfaces, while in the case of high-index surface orientations a monoclinic lattice d eformation is obtained. For the one-dimensional heterostructures, whic h are fabricated from superlattices grown on thick substrate crystals and are laterally confined by air, a lower symmetry lattice deformatio n than a tetragonal one may also occur for the [001]-substrate orienta tion, as a result of the anisotropic elastic lattice relaxation. In zi ncblende heterostructure, these particular strain fields can generate high internal electric fields. In two-dimensional heterostructures, th ese piezoelectric fields appear for the [111] or for higher-index inte rface orientations. However, in one-dimensional heterostructures the s train fields can generate high piezoelectric fields even for the high- symmetry [001]-interface orientation.