2 July 1998 Mechanisms of droplet formation in pulsed laser growth of thin oxide films
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Proceedings Volume 3405, ROMOPTO '97: Fifth Conference on Optics; (1998) https://doi.org/10.1117/12.312756
Event: ROMOPTO '97: Fifth Conference on Optics, 1997, Bucharest, Romania
The role of the sub-surface explosive boiling mechanism for droplet formation during the pulsed laser deposition of thin films has been examined. For photons with an energy lower than the target optical band-gap, hv<Eg, a highly perturbed target surface morphology exhibiting micrometer sized round- shaped cavities always formed, whereas for hv>Eg the surface was much less perturbed. Depth-profile estimations of the temperature profiles inside the laser irradiated targets were also quite different for these two cases. For low optical absorption coefficient (OAC) values, (alpha) < 5 X 104 cm-1, a thick layer of liquid formed whose maximum temperature was located at some point below the surface. Simultaneous to the cavity formation, the droplet density on the surface of the grown films was found to increase by orders of magnitude, indicating a clear connection between the target OAC, the temperature profile, the presence of the cavities and a high droplet density. The decrease of the OAC value during prolonged laser ablation could also explain the gradual increase of the droplet density observed when growing La0.5Sr0.5CoO3 films. Based on these results, we suggest that an important fraction of the droplets on the surface of films grown under laser irradiation conditions where the OAC is smaller than 5 X 104 cm-1 is caused by an explosive sub-surface boiling mechanism.
© (1998) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Valentin Craciun, Valentin Craciun, Doina Craciun, Doina Craciun, M. C. Bunescu, M. C. Bunescu, Eugen Vasile, Eugen Vasile, A. Ioncea, A. Ioncea, Razvan V. Dabu, Razvan V. Dabu, Ian W. Boyd, Ian W. Boyd, } "Mechanisms of droplet formation in pulsed laser growth of thin oxide films", Proc. SPIE 3405, ROMOPTO '97: Fifth Conference on Optics, (2 July 1998); doi: 10.1117/12.312756; https://doi.org/10.1117/12.312756

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