Kulyk V. Angular and energy distributions of ions emitted from one-element and alloy liquid metal ion sources

It has been obtained experimentally by the mass spectrometric investigation the emission characteristics of liquid metal ion sources (LMIS) depending on the temperature of alloy, elemental composition of the alloys and value of emission currents of the sources. For alloy sources, it has been found that by introducing an element with the tendency to segregation in surface layers it is possible to control angular and energy distributions of ions emitted from the source. Angular ion distributions become narrower while their energy spread decreases provided that the ionization potential of the segregating element is higher than the ionization potential of the main (matrix) element. It have been found for the first time an abrupt change of the character of their operation under transition from the range of the intermediate emission currents to the range of the onset emission currents. For a proper critical current for each source Icr, there occurs an abrupt change of the current itself and of the emissi on cone angle. The obtained results on the energy and angular ion distributions give evidence that for currents that are close to the critical values the emission parameters are optimum. The results are of immediate interest (microelectronics, solid-state physics, metallurgical engineering) mainly because of the important techological applications of focussed ions beams of LMIS: in microfabrication, microimplantation, lithography and deposition, submicron surface analysis.