Negative ion beam technology for materials science (invited)

Negative-ion beams can be used in materials science, i.e., ion implantation and ion beam deposition, since various types of high current negative-ion sources have recently been developed. Two types of these the NIABNIS and rf sputter types, were developed by the present authors. There are major differences between negative- and positive-ion implantations with regard to beam transport (collisional cross sections with residual gas particles) and secondary electron emission factors, but little difference in the projected ranges of implanted ions. By using negative ions in ion beam deposition, the effects of the kinetic energy and number of atoms of an ion may be clarified because negative ions have much less reactivity resulting from their internal potential energy of electron affinity than do positive ions resulting from their ionization potential.