An in-depth investigation of the energy distribution of doubly charged ions emitted from a liquid metal alloy ion source

We investigate the energy spread, dE½, vs emission current, i, of the doubly-charged ions emitted by a Au77Ge14Si9 Liquid Metal Alloy Ion Source (LMAIS). For the ionic species of main interest, namely Ge++, two modes were found with regard to the dependence of dE½ on i. In the first mode dE½ ~ i^ 0.3 and in the second dE½ ~ i . The difference is attributed to changes in the composition of the alloy during field-evaporation. Au++ an Si++ were also found to obey a dE½ ~ i^ 0.3 law; in the case of Si++ however, there is a deviation from this law at high currents.