Velocity distribution of micron-size particles in thin film laser ablation deposition (LAD) of metals and oxide superconductors

Dupendant, H.; Gavigan, J. P.; Givord, D.; Liénard, A.; Rebouillat, J.P.; Souche, Y.

doi:10.1016/0169-4332(89)90241-9

Cited by 65 publications

(25 citation statements)

References 8 publications

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“…Reported emission velocities of the droplets are on the order of 100 m/s, almost independent of the materials. [21][22][23] Since the velocity of the droplets is much smaller than that of the atoms, LIF signals originating from the droplets, if there are any, are observed at larger time delays than those at which the 251 and 288 nm LIF signals, originating from the laser ablated atoms, are generated. We have found that the 251 and 288 nm signals appear at t d of 0.2-100 s when the probe laser is off-resonant ͑251.8 nm͒ as well as when it is resonant ͑251.6 nm͒, as shown in Fig.…”

Section: B Light Scattering and Emission Originating From Dropletsmentioning

confidence: 99%

Laser-induced fluorescence from collisionally excited Si atoms in laser ablation plume

Okano

Takayanagi

1999

Journal of Applied Physics

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Laser-induced fluorescence ͑LIF͒ from neutral Si atoms in a laser ablation plume is investigated using a probe laser beam at 251.6 nm. Fluorescence at 288 nm from the 4s( 1 P 1 ) state is observed, aside from the deexcited fluorescence at 251.6 nm from the 4s( 3 P 2 ) state. The coincidence of the 288 nm fluorescence and the 251 nm fluorescence strongly indicates that the Si atoms in the 4s( 3 P 2 ) state are responsible for the 288 nm fluorescence. The 288 nm LIF signal is detectable only when the probe laser beam passes near the Si surface, and has maximum intensity for a time delay of 20 ns. The 288 nm LIF could be emitted when the Si atoms in the 4s( 3 P 2 ) state, pumped by the probe laser, collide with other Si atoms in the gas phase, since a high-density gas phase of ejected particles exists near the surface. The LIF intensities from the ablated Si atoms decrease for large time delays of the probe laser ͑0.2 sϽt d Ͻ100 s͒, and the 288 nm fluorescence originating from the droplets ͑probably microparticles͒ is observed instead. Since droplets moving at ϳ100 m/s are fragmented by the probe beam, the collisional excitation among these fragmented atoms can generate Si atoms in the 4s( 1 P 1 ) state.

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Section: B Light Scattering and Emission Originating From Dropletsmentioning

confidence: 99%

Laser-induced fluorescence from collisionally excited Si atoms in laser ablation plume

Okano

Takayanagi

1999

Journal of Applied Physics

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“…[3][4][5] Rotating vanes or shutters, 4,5 utilizing the fact that particulate velocities are significantly lower than those for atomic and molecular species, can however be used to intercept particulates before reaching the substrate. The dependence of particulate emission on the laser ablation processing parameters is discussed elsewhere.…”

Section: Introductionmentioning

confidence: 99%

Polar distribution of ablated atomic material during the pulsed laser deposition of Cu in vacuum: Dependence on focused laser spot size and power density

Weaver

Lewis

1996

Journal of Applied Physics

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Experiments have been carried out to investigate the polar distribution of atomic material ablated during the pulsed laser deposition of Cu in vacuum. Data were obtained as functions of focused laser spot size and power density. Thin films were deposited onto flat glass substrates and thickness profiles were transformed into polar atomic flux distributions of the form f ͑͒ϭcos n . At constant focused laser power density on target, Iϭ4.7Ϯ0.3ϫ10 8 W/cm 2 , polar distributions were found to broaden with a reduction in the focused laser spot size. The polar distribution exponent n varied from 15Ϯ2 to 7Ϯ1 for focused laser spot diameter variation from 2.5 to 1.4 mm, respectively, with the laser beam exhibiting a circular aspect on target. With the focused laser spot size held constant at ϭ1.8 mm, polar distributions were observed to broaden with a reduction in the focused laser power density on target, with the associated polar distribution exponent n varying from 13Ϯ1.5 to 8Ϯ1 for focused laser power density variation from 8.3Ϯ0.3ϫ10 8 to 2.2Ϯ0.1ϫ10 8 W/cm 2 , respectively. Data were compared with an analytical model available within the literature, which correctly predicts broadening of the polar distribution with a reduction in focused laser spot size and with a reduction in focused laser power density, although the experimentally observed magnitude was greater than that predicted in both cases.

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“…To reduce the droplet number, the laser fluence used and position of the substrate can be optimized, and the target surface has to be as smooth (and dense) as possible. Completely dropletfree films can be obtained by using mechanical velocity filters between target and substrate [Barr, 1969;Dubowski, 1986;Cherief et al, 1993], which allow the fast atoms and ions to reach the substrate but remove the slower droplets with velocities of 5200 m/s [Dupendant et al, 1989;Spindler et al, 1996;Fähler et al, 1997] during their transit to the substrate. Another interesting technique to avoid droplets is to use a dual-beam ablation geometry, where the line-of-sight direction to the substrate is obscured by shutters [Pechen et al, 1992;Gorbunov et al, 1996], and also see Chapter 6.…”

Section: Droplet Reductionmentioning

confidence: 99%

Pulsed Laser Deposition of Metals

Krebs

2006

Pulsed Laser Deposition of Thin Films

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Velocity distribution of micron-size particles in thin film laser ablation deposition (LAD) of metals and oxide superconductors

Cited by 65 publications

References 8 publications

Laser-induced fluorescence from collisionally excited Si atoms in laser ablation plume

Laser-induced fluorescence from collisionally excited Si atoms in laser ablation plume

Polar distribution of ablated atomic material during the pulsed laser deposition of Cu in vacuum: Dependence on focused laser spot size and power density

Pulsed Laser Deposition of Metals

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