화학공학소재연구정보센터
Applied Surface Science, Vol.254, No.4, 1220-1223, 2007
Ferntosecond pulsed laser ablation deposition of tantalum carbide
In this work a frequency-doubled Nd:glass laser with a pulse duration of 250 fs has been used to ablate a TaC target and to deposit thin films on silicon. The results have been compared with those previously obtained by nanosecond pulsed laser deposition and evidence of large differences in the plasma characteristics has been revealed. In particular, in the femtosecond and nanosecond plumes the energy and the velocity of neutral and ionized particles are very different. The features of femtosecond ablation include the delayed emission from the target of large and slow particles. The characteristics of the femtosecond plasma are clearly related to the morphology and composition of the deposited films and the results show a nanostructure consisting of a large number of spherical particles, with a mean diameter of about 50 nm, with a stoichiometry corresponding to Ta2C. To explain these features, an ablation-deposition mechanism, related to the ejection of hot particles from the target, is proposed. (C) 2007 Elsevier B.V. All rights reserved.