Ge Ion implant from energetic Lasergenerated plasma

Abstract

En At the PALS laboratories of Prague (Czech republic), IPPLM of Warsaw (Poland) and INFNLNS of Catania (Italy) experimental tests have been carried out to implant Ge ions in Si substrates through laser-generated Ge-plasma. Si substrates were placed in a vacuum chamber at different distances and angles from the Ge-target. Online measurements of ion energy were obtained by time of flight (TOF) techniques using an ion energy analyzer IEA which permitted to draw information about the charge states and the Ge ion’s energies. Off-line measurements were obtained by Rutherford backscattering spectrometry (RBS) of 2.25 MeV He2+ beam at CEDAD Laboratory of Brindisi (Italy). RBS analysis permitted to evaluate the Ge implant in Si substrate in terms of concentration and ion depth profile. Moreover, the RBS spectra have given information about plasma ion yield and energy as a function of the laser intensity, distance from the target and angular position. Results indicated that ion implants show high Ge ion energy and typical deep profiles only for substrates placed very near to the normal to the target surface and for high laser pulse intensity, while for low laser intensities and/or for substrates far from the normal to the target there is only a Ge deposition effect.