ECR Based Low Energy Ion Beam Facility at VECC, Kolkata

Abstract

A low energy heavy ion irradiation/implantation facility has been developed at VECC, Kolkata for materials science and atomic physics research, utilizing indigenously developed 6.4 GHz ECR ion source. The facility provides high charge state ion beams of N, O, Ne, Ar, S, Kr, Xe, Fe, Ti, Hf etc. up to a few micro amperes to an energy of 10 keV per charge state.The beam energy can be further enhanced by floating the target at a negative potential (up to 25 kV). The ion beam is focused to a spot of about 2 mm diameter on the target using a set of glaser lenses. A x-y scanner is used to scan the beam over a target area of 10 mm x 10 mm to obtain uniform implantation. The recently commissioned multi facility sample chamber has provision for mounting multiple samples on indigenously developed disposable beam viewers for insitu beam viewing during implantation. The ionization chamber of ECR source is mainly pumped by ECR plasma. An additional pumping speed has been provided through extraction hole and pumping slots to obtain low base pressure. In the ion source, base pressure of 1x10−7 Torr in injector stage and ~5x10−8 Torr in extraction chamber have been routinely obtained. The ultra-high vacuum multi facility experimental chamber is generally kept at ~ 1x10−7 Torr during implantation on the targets. This facility is a unique tool for studying fundamental and technologically important problems of materials science and atomic physics research. High ion flux available from this machine is suitable for generating high defect densities i.e. high value of displacement-per-atom (dpa). Recently this facility has been used for studies like "Tunability of dielectric constant of conducting polymer Polyaniline (PANI) by low energy Ar9+ irradiation" and "Fe10+ implantation in ZnO for synthesis of dilute magnetic semiconductor".