Formation, Dynamics, and Characterization of Nanostructures by Ion Beam Irradiation

Abstract

Ion beam irradiation is a potential tool for phase formation and material modification as a non-equilibrium technique. Localized rise in temperature and ultra fast (∼10⁻¹² s) dissipations of impinging energy make it an attractive tool for metastable phase formation. As a matter of fact, a major component of materials science is dominated by ion beam methods, either for synthesis of materials or for its characterization. The synthesis of nanostructures, and their modification by ion beam technique will be discussed in this review article. Formation of nanostructures using ion beam technique will be discussed first. Depending on species (e.g., mass and charge state) and energy range, there are various modes for an energetic ion to dissipate its energy. The role of the electron will also be covered in this article as a basic principle of its interaction with matter, which is same as for an ion. By using a simple reactive ion beam or electron induced deposition, a secondary phase can be nucleated by ion beam mixing techniques, either by using inert gas irradiation or reactive gas implantation on any desired substrate. Nucleation of secondary phase can also be executed by electron irradiation and direct implantation of either negative or positive ions. Post implantation annealing processes are required for the complete growth of clusters formed in most of these ion irradiation techniques. Implantation processes being inherently a non-equilibrium technique, defects always have a role to play in phase formation, amorphization, and beyond (blister formation). When implanted with large energy, even electrons, one of the lightest charged particles, also manifest these properties. Electronic and nuclear energy losses of the impinging charged particle play a crucial role in material modification. Doping a nanocluster, however, is still a controversial topic. Some light will be shed on this topic with a discussion of focused ion beam.

Keywords:

• focused ion beam
• dynamic annealing
• phase transition
• doping
• amorphization
• blister

ACKNOWLEDGMENTS

I sincerely acknowledge all researchers whose contribution to the understanding of nanostructures by ion beam technique missed our notice. I acknowledge the help of all researchers who very kindly provided us with the original figures used in this review. I thank all publishers who kindly granted us the permission to reproduce figures and pictures for which they hold the copyright. I bestow my gratitude toward Prof. L. C. Chen of Center for Condensed Matter Sciences (CCMS), National Taiwan University, Taipei, Taiwan for exchanging scientific ideas and encouragement for writing this article. I am also grateful to Prof. K. H. Chen and Prof. Y. L. Wang of Institute of Atomic and Molecular Sciences (IAMS), Taipei, Taiwan for their guidance and assistance in making this article worthy. I am also deeply in gratitude to Dr. Baldev Raj, the Director IGCAR, and Dr. K. G. M. Nair of particle irradiation facility section, MSD, IGACR for their persistent encouragement in performing quality research and grooming my scientific career. A special note of thanks goes to Dr. Sharat Chandra of MSD, IGCAR, India and Mr. Biswanath Sen of Engineering Service Group, IGCAR, India for detailed reading of the manuscript and useful suggestions.