Radiation Effects & Defects in Solids
Vol. 163, Nos. 4–6, April–June 2008, 401–409
Ge laser-generated plasma for ion implantation
L. Giuffrida
a
*, L. Torrisi
b,c
, A. Czarnecka
d
, J. Wolowski
d
, G. Quarta
e
, L. Calcagnile
e
,
A. Lorusso
f
and V. Nassisi
f
a
Dipartimento di Fisica, Università di Catania, Catania, Italy;
b
Dipartimento di Fisica, Università
di Messina, Messina, Italy;
c
INFN-Laboratori Nazionali del Sud, Catania, Italy;
d
Institute of Plasma
Physics and Laser Microfusion,Warsaw, Poland;
e
CEDAD, Dipartimento di Ingegneria dell’Innovazione,
Università di Lecce, Lecce, Italy;
f
LEAS, Department of Physics, University of Salento INFN-Lecce,
Lecce, Italy
(Received 15 April 2007; in final form 5 November 2007 )
Laser-generated plasma obtained by Ge ablation in vacuum was investigated with the aim to implant
energetic Ge ions in light substrates (C, Si, SiO
2
). Different intensities of laser sources were employed
for these experiments: Nd:Yag of Catania-LNS; Nd:Yag ofWarsaw–IPPL; excimer laser of Lecce-INFN;
iodine laser of Prague-PALS.
Different experimental setups were used to generate multiple ion stream emissions, multiple ion
energetic distributions, high implantation doses, thin film deposition and post-acceleration effects.
‘On line’ measurements of ion energy were obtained with ion collectors and ion energy analyzer in time-
of-flight configuration. ‘Off line’ measurement of Ge implants were obtained with 2.25 MeV helium beam
in Rutherford backscattering spectrometry. Results indicated that ion implants show typical deep profiles
only for substrates placed along the normal to the target surface at which the ion energy is maximum.
Keywords: laser ablation; laser-plasma; ion implantation; RBS analysis
1. Introduction
Intense laser pulses irradiating solid targets generate hot plasmas with high temperature and high
density. Plasma expands in vacuum at supersonic velocity along the normal to the target surface
accelerating electrons, ions and neutrals. Plasma contains ions at high-charge states and velocity,
which energy distribution follows Boltzmann functions typical of non-equilibrium conditions (1).
Interesting information can be obtained by time-of-flight (TOF) measurements of ions, which
indicate the presence of an high-electrical field inside the plasma responsible of the high ion
acceleration along the normal to the target surface, as demonstrated by angular distribution
measurements (2).
The ion energy depends strongly on the intensity of the laser pulse and on the irradiated target
material. At laser intensities of the order of 10
10
W/cm
2
the ion energies reach about 10 keV while
at intensities of the order of 10
15
W/cm
2
it reach values of few MeV (3).
*Corresponding author. Email: necrorius@hotmail.com
ISSN 1042-0150 print/ISSN 1029-4953 online
© 2008 Taylor & Francis
DOI: 10.1080/10420150701777900
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