Ablation, melting, and smoothing of polycrystalline alumina by pulsed excimer laser radiation
- Oak Ridge National Lab., TN (United States)
- Tennessee Univ., Knoxville, TN (United States). Dept. of Materials Science and Engineering
Effects of pulsed XeCl (308 nm) laser radiation on polycrystalline Al{sub 2}O{sub 3} (alumina, 99.6% pure) and single-crystal Al{sub 2}O{sub 3} (sapphire) are studied as a function of laser fluence. No laser etching of either material is detected below a threshold fluence value (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 {ge}0.7 J/cm{sup 2}. 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/cm{sup 2}). 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. 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.
- Research Organization:
- Oak Ridge National Lab., TN (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 10117907
- Report Number(s):
- CONF-921101-26; ON: DE93005148
- Resource Relation:
- Conference: 16. Materials Research Society (MRS) fall meeting,Boston, MA (United States),30 Nov - 5 Dec 1992; Other Information: PBD: Nov 1992
- Country of Publication:
- United States
- Language:
- English
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