Depth-dependent disordering ina-Si produced by self-ion-implantation

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Abstract
Raman scattering from amorphous silicon (a-Si) produced by self-ion-implantation reveals an exciting wavelength-dependent scattering-intensity ratio of the optical- and the acoustic-phonon-like peaks. The results show that this wavelength-dependent scattering originates from a depth-dependent disordering. The surface part (∼200 Å) of the samples demonstrates weaker long-range disordering, while the internal part demonstrates stronger long-range disordering. After annealing at 500 °C for an hour this inhomogeneity disappears. This is explained as the elimination of certain defects that strongly influence the longer-range order of the lattice. These defects relax spontaneously at the surface during the ion implantation.