Ablation, melting, and smoothing of polycrystalline alumina by pulsed excimer laser radiation

Douglas H. Lowndes, M. DeSilva, M. J. Godbole, A. J. Pedraza, D. B. Geohegan

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

17 Scopus citations

Abstract

The effects of pulsed XeCl (308 nm) laser radiation on polycrystalline Al2O3 (alumina, 99.6% pure) and single-crystal Al2O3 (sapphire) are studied as a function of laser fluence. No laser etching of either material is detected below a threshold fluence value, which is much lower for alumina than for sapphire. Above this threshold, laser etching of both materials is observed following a number of incubation (induction) pulses. This number is much larger for sapphire than for alumina but decreases with increasing fluence for both materials. Laser etching rates for the two materials are similar at high fluences and after the incubation period. Scanning electron microscope images show that alumina melts and flows under repeated irradiation at fluences ≥0.7 J/cm2. Atomic force microscopy and surface profilometry reveal significant smoothing of the as-received polycrystalline alumina surface after repeated irradiations at moderate fluences (approximately 1-3 J/cm2). Ion probe measurements for alumina in vacuum confirm the incubation behavior, and reveal that at fixed fluence the (positive) charge collected per pulse saturates after a sufficient number of pulses, as does the etch-plume velocity. The results are interpreted in terms of laser-generation of a sufficient concentration of absorption centers before efficient ablation/etching of these wide bandgap materials can occur.

Original languageEnglish
Title of host publicationMaterials Research Society Symposium Proceedings
PublisherPubl by Materials Research Society
Pages191-196
Number of pages6
ISBN (Print)1558991808
StatePublished - 1993
EventLaser Ablation in Materials Processing: Fundamentals and Applications - Boston, MA, USA
Duration: Dec 1 1992Dec 4 1992

Publication series

NameMaterials Research Society Symposium Proceedings
Volume285
ISSN (Print)0272-9172

Conference

ConferenceLaser Ablation in Materials Processing: Fundamentals and Applications
CityBoston, MA, USA
Period12/1/9212/4/92

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