Effect of initial plasma geometry and temperature on dynamic plume expansion in dual-laser ablation

Abstract

Recent experiments have revealed the capability of large-area, uniform film growth using dual-laser ablation. The mechanism of this dynamic plume expansion is investigated in this letter. We report the critical role played by the initial geometry and temperature of the plasma in the subsequent expansion under dual-laser ablation. Initial plasma dimensions in the dual-laser ablation of ZnO are quantified by gated intensified charge-coupled detector-array imaging and combined with a hydrodynamic theoretical expansion model to yield radial thickness profiles for the deposited films. Comparisons with ellipsometric film thickness profiles indicate that the primary factors responsible for increased expansion of the dual-laser ablated plume are an extension of the initial plasma dimension in the axial direction as well as enhanced plasma temperature. © 1999 American Institute of Physics.