Binary-collision-cascade simulation of hyperchanneling of high-energy helium ions in silicon

Abstract

The binary-collision-cascade code, marlowe, was modified to include an accurate electron-density distribution of silicon and an electronic-energy-loss (EEL) model that is suitable for high-energy studies. The EEL model is based on a theory that relates the energy loss and local valence-electron density via a phenomenological band-structure model. The enhanced marlowe is applied to simulate transmission spectra due to the hyperchanneling of high-energy α particles in silicon along the [110] and [111] directions. The transmission spectra due to a ''random'' incident direction was also studied. The channeling peak positions in the energy-transmission spectra agree fairly well with the measurements. The effects of transverse-energy distribution of the incident beam, the effects of electron-multiple scattering and energy-loss straggling, and the effects of nonuniformity of the electron density on the transmission spectra are discussed. The electron-density effects reproduce the stopping-power measurements based on the peak and leading edge of the energy spectrum. The importance of energy-loss straggling, of core-electron contribution to the energy loss at high energies, and of charge-state effects at intermediate energies is also discussed. © 1993 The American Physical Society.