MOLECULAR-DYNAMICS SIMULATIONS OF THE STABILITY OF AMORPHOUS-SILICON

We have performed molecular-dynamics simulations as a first step towards understanding the Staebler-Wronski effect in amorphous silicon, utilizing classical silicon potentials and computer-generated amorphous silicon structures. A localized hot spot is used to model the nonradiative transfer of photoexcited carrier energy to the lattice. This leads to structural degradation in a-Si networks in which weak Si-Si bonds are broken and dangling bonds are produced, requiring a threshold energy of about 0.8-1.0 eV. Thermal annealing of an a-Si model with coordination defects is also described.