The shape dependence of vicinal Si(001) surfaces on the applied uniaxial strain direction is studied. This dependence is intimately related to the anisotropic nature of the intrinsic strain field which originates from the surface dimerization. The strain relief mechanism is shown to be different in two orthogonal directions. Normal to the steps, step-pair bunching and waving lead to formation of hillocks and pits. Along the step direction, bending of step pairs forms a cusp which later develops into a deep groove.

• Received 23 May 1996

DOI:https://doi.org/10.1103/PhysRevLett.77.2021