ELSEVIER zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA surfa c e sc ie nc e Applied Surface Science 96-98 (1996) 159-163 Transport of neutral atoms, monoxides and clusters in the plume produced by laser ablation of YBa,Cu,O,_, in oxygen environment A.V. Bulgakov *, M.R. Predtechensky, A.P. Mayorov Institute zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA of Thermophysics, Prospect Lmrentyeu 1, 630090 Nouosibirsk, Russia Received 22 May 1995 Abstract The dynamics of various neutral particles during laser ablation of YBa,Cu,O,_, in the 0, ambient gas is investigated using post ablation ionization mass spectrometty in combination with molecular beam technique. The 0, environment is found to favor oxide cluster formation in the ablation plume. The pressure above - 100 mTorr results in a pulsating character of the plume expansion within a finite propagation distance. 1. Introduction Laser ablation of oxides has gained particular attention as a successful method for obtaining films of high-T, superconductors, especially YBa,Cu,O,_, (YBCO). It is known that ambient atmosphere greatly affects the quality of deposited films, but details of the interaction between laser-in- duced plume and background gas have not been sufficiently understood. The plume expansion dy- namics has been studied extensively by emission spectroscopy [l-3]. However, these techniques are limited by detection of emissive species, and do not enable the characterization of the fairly late interac- ’ Corresponding author. Tel.: + 7-3832 39-10-45; fax: +7-3832 35-78-80; e-mail: predtech@otani.thermo.nsk.su. tion stages (roughly, N 100 laser pulse duration after ablation) when the neutral particles in their ground states appear to be the major constituents in the plume. Recently, LIF spectroscopy [4,5] and post ablation ionization mass spectrometry (PAIMS) [6] have been applied to investigate the atomic and molecular particle behavior over a wide range of the interaction times. As shown in the experiments on laser ablation of YBCO in vacuum [7-91, clusters of wide mass range are present in abundance among the plume con- stituents at low laser fluence, near ablation threshold, and disappear at higher fluences. Under deposition conditions, the value of irradiance required is usually several times higher than the threshold value, but this does not necessary mean that clusters play a minor role in film deposition. In 0, environment, the con- centrations of plume mono- and polyoxides increase with the ambient pressure [2-4,101. Moreover, the 0169-4332/96/$15.00 0 1996 Elsevier Science B V. All rights reserved SSDI 0169-4332(95)00472-6