Kinetic and thermodynamic enhancement of crystal nucleation and growth rates in amorphous Si film during ion irradiation

Abstract

The effect of 1.5 MeV Xe + irradiation at elevated substrate temperatures on the crystal nucleation rate and on the subsequent crystal growth rate in amorphous Si has been investigated. The analysis of apparent activation energies obtained for the nucleation rate, growth rate, and incubation time suggests that the interfacial rearrangement kinetics of subcritical nuclei and large crystals may be similarly affected by the incident ions. The observed rates of crystal growth show excellent agreement with a recently proposed defect model for ion-induced crystallization in the ion flux and temperature regime where both the ion-generated and thermally generated defects contribute significantly to the total crystal growth rate. The nucleation rate is found to be more dramatically enhanced by ion irradiation than either the growth rate or the incubation time. This suggests enhancement in the total nucleation rate under irradiation that is of a thermodynamic origin due to transient unrelaxation within a defect-rich cascade created by the incident ion.