Field-ion specimen preparation using focused ion-beam milling

Preparation of field-ion specimens from various materials has been accomplished using focused ion-beam milling in either a simple cutting mode or by application of an annular-shaped ion-milling pattern. These specimens have been investigated using field-ion microscopy and three-dimensional atom probe analysis. In the cutting mode, gallium implantation is minimised when using a lower beam energy. However, with annular milling, using 30 keV ions opposed to 10 keV ions results in less gallium implantation and produces a smaller shank angle and a sharper apex radius. High-dose ion imaging at 30 keV ion energy, even with relatively low beam currents, results in excessive implantation during field-ion specimen fabrication. Focused ion-beam milling provides not only an alternative method of field-ion sample preparation, but also, in conjunction with atom probe analysis, allows the quantitative investigation of the gallium implantation and damage which occurs during the milling.