EVIDENCE OF ENHANCED EPITAXIAL CRYSTALLIZATION AT LOW-TEMPERATURE BY INELASTIC ELECTRONIC SCATTERING OF MEGA-ELECTRON-VOLT HEAVY-ION-BEAM IRRADIATION

The inelastic electronic scattering of Kr-84 at energies of 0.5-5 MeV and Xe-131,Xe-132 ions at energies of 1-5 MeV is directly confirmed to play a role in the ion-beam-induced epitaxial crystallization (IBIEC) of amorphous Si layers on crystalline Si substrates at 310-450 degree s C. The crystallization rate per unit vacancy (normalized crystalliza tion rate) created by the elastic nuclear scattering of the incident i on beam at the amorphous-crystalline (a/c) interface is increased 40%- 50% by increasing the inelastic electronic scattering three- to fourfo ld while maintaining the same elastic nuclear scattering conditions at the a/c interface. This normalized crystallization rate also increase s with the inelastic electronic scattering at the a/c interface. Howev er, the percentage of increase falls to about 20% as the absolute valu e of the inelastic electronic energy loss at the a/c interface decreas es to below about 20 keV/ion/(20 nm) or as the number of vacancies cre ated at the a/c interface increases to more than 250/ion/(20 nm). At 3 10-450 degrees C the activation energy for IBIEC induced by Kr or Xe i rradiation is 0.5-0.6 eV. This value slightly larger than the 0.2-0.3 eV reported for temperatures below 300 degrees C reflects the thermall y activated solid-phase epitaxy. The mechanism of this enhanced crysta llization by inelastic electronic scattering is discussed qualitativel y. (C) 1996 American Institute of Physics.