engleski

Ion fluence measurements for microprobe irradiation using low beam currents and single ions

Low current irradiation is an important application of ion microprobe in the field of materials modification. As different ion species interact in a different way with the irradiated material, depending also on their energy, it does not exist a unique technique for the reliable ion fluence measurement. In single ion applications such as formation of ion tracks using swift heavy ions, detection of secondary electrons or photons that are emitted from the sample surface or scintillating surface layer can be used for reliable ion hit detection. In some applications transmitted ions (STIM), or charge signals (IBIC) can be utilized as well. For low currents of light ions, direct current measurement may not be possible, or is not sufficiently reliable. In these cases x-rays can be used for fluence normalization as well. In this work we discuss advantages and limitations of all these techniques, on the basis of efficiency measurements we performed for single ion hit detection. Protons, He, C and Si ions in the energy range from several hundred keV for light ions up to tens of MeV for heavier ions were used. We also present two application examples, namely ion track formation in polymers and structuring of electronic defects in semiconductor devices where reliable ion fluence measurement or ion hit detection is of prime importance.

swift heavy ion; ion track; ion microprobe

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