Depth-dependent disordering in<i>a</i>-Si produced by self-ion-implantation

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 (\ensuremath{\sim}200 \AA{}) of the samples demonstrates weaker long-range disordering, while the internal part demonstrates stronger long-range disordering. After annealing at 500 \ifmmode^\circ\else\textdegree\fi{}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.