analysable in atom probe, however sample preparation may be more difficult, and interpretation of results may be more complex, particularly if the semi-conductor contains phases which evaporate at differing electric field strengths. Applications such as ion implantation may be used to identify the distribution of dopants inside a semi-conducting material, which is increasingly critical in the correct design of modern nanometre scale electronics. Limitations Materials implicitly control achievable spatial resolution. Specimen geometry during the analysis is uncontrolled, yet controls projection behaviour, hence there is little control over the magnification. This induces distortions into the computer generated 3D dataset. Features of interest might evaporate in a physically different manner to the bulk sample, altering projection geometry and the magnification of the reconstructed volume. This yields strong spatial distortions in the final image. Volume selectability can be limited. Site specific preparation methods, e.g. using Focussed ion beam preparation, although more time-consuming, may be used to bypass such limitations. Ion overlap in some samples (e.g. between oxygen and sulfur) resulted in ambiguous analysed species. This may be mitigated by selection of experiment temperature or laser input energy to influence the ionisation number (+, ++, 3+ etc.) of the ionised groups. Data analysis can be used in some cases to statistically recover overlaps. Low molecular weight gases (Hydrogen & Helium) may be difficult to be removed from the analysis chamber, and may be adsorbed and emitted from the specimen, even though not present in the original specimen. This may also limit identification of Hydrogen in some samples. For this reason, deuterated samples have been used to overcome limitations. Results may be contingent on the parameters used to convert the 2D detected data into 3D. In more problematic materials, correct reconstruction may not be done, due to limited knowledge of the true magnification; particularly if zone or pole regions cannot be observed. References Further reading Michael K. Miller, George D.W. Smith, Alfred Cerezo, Mark G. Hetherington (1996) Atom Probe Field Ion Microscopy Monographs on the Physics and Chemistry of Materials, Oxford: Oxford University Press. . Michael K. Miller (2000) Atom Probe Tomography: Analysis at the Atomic Level. New York: Kluwer Academic. Baptiste Gault, Michael P. Moody, Julie M. Cairney, SImon P. Ringer (2012) Atom Probe Microscopy, Springer Series in Materials Science, Vol. 160, New York: Springer. David J. Larson, Ty J. Prosa, Robert M. Ulfig, Brian P. Geiser, Thomas F. Kelly (2013) Local Electrode Atom