Investigations on a Co–Dy liquid alloy ion source

Abstract

We have investigated the emission characteristics of a Co–Dy liquid alloy ion source intended for focused ion beam implantation of cobalt and dysprosium ions. An alloy composition of Co2Dy was selected in order to have a relatively low melting temperature, sufficient cobalt concentration for ion implantation purposes and low corrosion effects of the alloy and emitter tungsten wires. We have measured the melting behaviour of the alloy, the emission current stability, the current–voltage characteristics and the mass and energy spectra as a function of source current using a time-of-flight spectrometer. The ion source exhibits a good performance even after storage for several weeks in dry air. The mass spectra show a high intensity of doubly charged dysprosium ions and singly and doubly charged cobalt ions. The Co–Dy source works in a stable way for at least several days.