Ab initio modeling of optical functions after strain wave perturbation for defect detection

摘要

We model the change in the linear optical functions due to the propagation of a strain wave through a crystalline slab. Defects in the slab are introduced by arbitrarily displacing one of the atomic layers. The perturbing wave is assumed to be produced by laser light absorption; the properties of the propagating wave are explicitly related to the laser and material properties. We apply this model to a Si(111)(1x1):H slab and find that the reflectance varies significantly at photon energies above 2.5 eV and that the disordered slab produces significant changes in the reflectance when compared to the unperturbed slab. We then induce a defect layer in the slab by uniformly translating an atomic layer. As the strain wave passes through the material, the behavior of the calculated reflectance difference spectrum changes according to the defect layer, allowing us to discern the depth of the defect.