An unconventional ion implantation method for producing Au and Si nanostructures using intense laser-generated plasmas

Abstract

The present paper describes measurements of ion implantation by high-intensity lasers in an innovative configuration. The ion acceleration and implantation were performed using the target normal sheath acceleration regime. Highly ionized charged ions were generated and accelerated by the self-consistent electrostatic accelerating field at the rear side of a directly illuminated foil surface. A sub-nanosecond pulsed laser operating at an intensity of about 10 16 W cm −2 was employed to irradiate thin foils containing Au atoms. Multi-energy and multispecies ions with energies of the order of 1 MeV per charge state were implanted on exposed substrates of monocrystalline silicon up to a concentration of about 1% Au atoms in the first superficial layers.The target, laser parameters and irradiation conditions play a decisive role in the dynamic control of the characteristics of the ion beams to be implanted. The ion penetration depth, the depth profile, the integral amount of implanted ions and the concentration-depth profiles were determined by Rutherford back-scattering analysis. Ion implantation produces Si nanocrystals and Au nanoparticles and induces physical and chemical modifications of the implanted surfaces.

Laser-accelerated particle beams for stress testing of materials

“…2b ). Concerning the heavy ions co-moving with the proton beam (carbon, hydroxide, and gold), we consider that, as found in similar experiments 51 , their energy can generate a very widely distributed simple ion implantation on the target surface or sometimes produce a superficial coating effect (in particular the debris). However, their low fluence 48 (below 10 10 particles × MeV −1 × sr −1 for C and OH; 10 8 particles × MeV −1 × sr −1 for gold) does not produce the growth of any carbon, oxygen, or gold monolayer on the target surface 52 , 53 .…”

Low divergent MeV-class proton beam with micrometer source size driven by a few-cycle laser pulse

“…These systems, operating at kHz 37 , 38 or higher repetition rate, can generate MeV proton beams 32 , 33 and could provide the users with a similar average particle flux (although at much lower ion cut-off energy) compared to what multi-Joule laser systems on a single shot basis do. These MeV-class proton beams can find direct applications in areas such as ion-beam implantation 39 , ion injector in a conventional accelerator 40 , 41 , production of bright neutron flux via D(d, n) reaction 42 – 45 for transmutation of spent nuclear fuel 14 or recreation of rapid (r) process for nucleosynthesis 46 , 47 . Towards these goals, here we present the spatial characterization of a laser-driven proton beam generated at an intensity of 10 19 W/cm 2 with a 12 fs laser pulse.…”

Ion Beam Analysis applied to laser-generated plasmas

“…However XRD analysis shows the formation of Au crystalline aggregated at the Si surface, probably due to thermal assisted nanocrystallization effects. Preliminary AFM analysis indicates the presence of nanocrystals on the Si substrate [13].…”