MULTIPURPOSE NANOBEAM SOURCE WITH SUPERTIP EMITTER

Protrusions of 1 nm dimensions have been grown on single-crystal tips of tungsten and iridium of about 100 nm size. With positive bias the t ip can be operated as an intense ion source and with reversed bias int ense electron beams can be obtained. In both cases, specific brightnes s values of up to 1 TA/cm(2) srd eV have been recorded under optimized conditions. As for gases, tungsten can be used only for less reactive species, such as hydrogen and rare gases, whereas iridium is also use ful for aggressive gasses, such as oxygen. Both metals are excellent e lectron emitters. Thus, a powerful multipurpose source is realized wit h supertips of tungsten and iridium, as will be demonstrated by a vari ety of experimental results on their relevant properties. (C) 1998 Ame rican Vacuum Society.