ELASTIC LATTICE DEFORMATION IN QUANTUM-WIRE HETEROSTRUCTURES

We report on the lattice deformation of quantum-wire heterostructures with cubic symmetry deposited on arbitrarily oriented substrate surfac es. The elasic strain and the stress-tensor components are calculated by using Hooke's law and applying the appropriate boundary conditions at the wire-substrate interface. We assume that the lattice coherence at the wire-substrate interface is achieved only along the wire direct ion, due to the limted lateral extension of the wires. We show that ei ther a tetragonal or an orthorhombic or a lower-symmetry lattice defor mation of the quantum-wire structure may occur depending on the cohere nce direction and substrate orientation. In some particular cases, eve n for high-symmetry substrate orientations ([001] and [110]), it is po ssible to obtain one shear strain element different from zero, leading to a monoclinic lattice deformation. Moreover, for the [111] or low-s ymmetry substrate orientations a triclinic lattice deformation can als o be obtained. In the case of an orthorhombic lattice deformation our theoretical results are found to be in good agreement with the few exp erimental data available.