Computer simulation of atomic displacements in Si, GaAs, and AlAs

Abstract

Low energy displacement events produce simple point defects such as Frenkel pairs. Computer simulations of these events are useful as they provide information concerning the nature of damage in semiconductors, and can generate input parameters required for a theoretical study of cascades. Using molecular dynamics simulations we have investigated low energy displacement in Si, GaAs and AlAs for ejections below 32 eV. These materials are modelled using the Si Tersoff potential, which has been modified for the compound semiconductors. For each atomic species we have determined the displacement threshold energy, and its angular dependence together with an estimate of recombination distances. Several ejection processes have been identified. Their directional and energy dependencies will be discussed. The results for Si, GaAs and AlAs are compared and physical reasons are given for the similarities and differences.