Species-resolved imaging and gated photon counting spectroscopy of laser ablation plume dynamics during KrF- and ArF-laser PLD of amorphous diamond films

摘要

Gated photon counting spectroscopy and species-resolved ICCD photography were used to study the weak plasma luminescence following the propagation of the initial ablation plume in vacuum and during the rebound of the plume with a substrate during pulsed laser deposition of amorphous diamond. These methods techniques were required in order to investigate notable differences between amorphous diamond-like carbon films formed by pulsed laser deposition from ArF (193 nm) and KrF (248 nm) irradiation of pyrolytic graphite in vacuum. Three principal regions of plume emission were found: (1) a bright luminescent ball (v (approximately)3--5 cm/(mu)s) displaying nearly entirely C(sup +) emission which appears to result from laser interaction with the initial ejecta, (2) a spherical ball of emission (v (approximately) 1 cm/(mu)s) displaying neutral carbon atomic emission lines and, at early times, jets of excited C(sub 2), and (3) a well-defined region of broadband emission (v (approximately) 0.3 cm/(mu)s) near the target surface first containing emission bands from C(sub 2), then weak, continuum emission thought to result from C(sub 3) and higher clusters and/or blackbody emission from hot clusters or nanoparticles.