The expansion dynamics of the plasma generated during pulsed laser deposition of gold in vacuum has been investigated at the laser fluences of 2.5, 6.0, and 9.0 J cm−2. A severe distortion of the expansion is observed in the presence of a substrate that is accompanied at 9.0 J cm−2 by the appearance of a secondary plasma front expanding from the substrate surface. Langmuir probe analysis at 9.0 J cm−2 shows that the substrate surface is bombarded by a high transient flux of energetic Au+ ions 3.01019 ions cm−2 s−1 having very large kinetic energies 400 eV. Analysis of the plasma dynamics shows that these observations are consistent with self-sputtering of Au neutrals from the substrate induced by incident Au ions while a fraction of them are backscattered. Self-sputtering is found to be 2 orders of magnitude larger than backscattering. The comparison with experimental data allows concluding that the apparent recoil of the plasma front is caused by collision with self-sputtered neutrals, while the secondary emission is originated by backscattered ions.

Imaging self-sputtering and backscattering from the substrate during pulsed laser deposition of gold

RESTA, VINCENZO;
2007

Abstract

The expansion dynamics of the plasma generated during pulsed laser deposition of gold in vacuum has been investigated at the laser fluences of 2.5, 6.0, and 9.0 J cm−2. A severe distortion of the expansion is observed in the presence of a substrate that is accompanied at 9.0 J cm−2 by the appearance of a secondary plasma front expanding from the substrate surface. Langmuir probe analysis at 9.0 J cm−2 shows that the substrate surface is bombarded by a high transient flux of energetic Au+ ions 3.01019 ions cm−2 s−1 having very large kinetic energies 400 eV. Analysis of the plasma dynamics shows that these observations are consistent with self-sputtering of Au neutrals from the substrate induced by incident Au ions while a fraction of them are backscattered. Self-sputtering is found to be 2 orders of magnitude larger than backscattering. The comparison with experimental data allows concluding that the apparent recoil of the plasma front is caused by collision with self-sputtered neutrals, while the secondary emission is originated by backscattered ions.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11587/408451
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