Analyses of gas-phase reactions during reactive laser ablation using emission spectroscopy

Abstract

Time-and space-resolved emission spectroscopic measurements have been performed to investigate the formation of molecular species in the plasma plume generated by pulsed-laser ablation of Al, C and Ti targets in either N 2 or O 2 low-pressure atmospheres. The recorded spectra show that the interaction between the vapour plume and the ambient gas gives rise to the partial dissociation and ionization of the ambient gas and that the formation of nitride or oxide diatomics depends strongly on the binding energies of these species with respect to dissociation potential of the gas molecules. Thus, nitride formation in the gas phase occurred only during carbon ablation while oxide molecules were detected in the plasma plume originating from every target material. The influence of the atomic mass of the target material on the gas-phase reactions is also discussed. The results contribute to a better understanding of the mechanisms involved in the thin-film synthesis by reactive pulsed laser deposition.

Influence of in situ nitrogen pressure on crystallization of pulsed laser deposited AlN films

“…The lines with the highest [14] was also observed. This band arises from the directly ablated AlN clusters of the target material, since, as it was established [15], nitride formation in the plasma cannot be expected. The second and much weaker emission band of AlN(1,0) appearing at 527.60 nm [14] was absent in the spectra.…”

Imaging the dissociation process of O2 background gas during pulsed laser ablation of LiNbO3

“…Dissociation is possible because of the relatively low binding energy ͑5.12 eV͒ of O 2 and is caused by the collisions between O 2 molecules and the expanding plasma, leading also to excitation of the newly formed O atoms. While dissociation of O 2 has already been observed in earlier pulsed laser ablation experiments, 7,[11][12][13][14] the technique used in the present study allows for the first time to precisely localize and simultaneously characterize the O * distribution together with the distributions of the other excited neutral species involved, thus allowing a direct comparison of their relative positions and intensities. Moreover, this enhanced precision enables us to localize the dissociation process in space and time.…”

Titanium oxide nanostructured films by reactive pulsed laser deposition

“…easily produced starting from metallic targets [20] even though titanium oxide has been also employed as the starting material. Dense and compact films are usually produced at high substrate temperature (!150 8C) while a few works focused on room temperature deposition of TiO 2 with controlled properties [21][22][23].…”