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Laser-Target Interactions and its Effect on Surface Morphology of Laser Deposited thin films

Published online by Cambridge University Press:  26 February 2011

R. K. Singh ,
D. Bhattacharya  and
J. Narayan
R. K. Singh
Affiliation:
Materials Science and Engineering Department, University of Florida, Gainesville, FL 326112066
D. Bhattacharya
Affiliation:
Materials Science and Engineering Department, University of Florida, Gainesville, FL 326112066
J. Narayan
Affiliation:
Materials Science and Engineering Department, North Carolina State University, Raleigh, NC 27695-7916
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Abstract

The laser-target interactions during pulsed laser evaporation (PLE) of materials have been investigated in detail. Sub-surface temperatures have been calculated to be higher than the surface temperatures during planar surface evaporation of the target material. While the evaporating surface is being cooled due to the latent heat of vaporization, sub-surface superheating occurs due to the finite absorption depth of the laser beam. Detailed computer simulations have been carried out to understand the evaporation characteristics of different targets (Si, YBa2Cu3O7 ) as a function of laser and target variables. For silicon targets irradiated with 25 nanosecond laser pulses (energy density of 10J/cm2, absorption coefficient of 105 cm−1), the sub-surface temperatures were found to be more than 2000°C above the surface evaporation temperatures. The sub-surface superheating increased with increasing energy density and absorption depth. This internal superheating effects may lead to volume evaporation of the target where a solid material in form of particles may be ejected from the target surface. Based on the above understanding, parameters required to reduce the particle density in PLE films are predicted.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 201: Symposium A – Surface Chemistry and Beam-Solid Interactions , 1990 , 427
Copyright
Copyright © Materials Research Society 1991

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References

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