Surface Preserving Targeted Preparation using Focused Ion Beam Demonstrated by the Example of Oxide layers on Ni-Ti Alloys

Abstract

The use of focused ion beams, whilst permitting the targetted preparation of thin specimens for Transmission Electron Microscopy, also results in modification of the material to be investigated as a result of energy being transferred into the material. This undesirable effect is normally limited to the surface of the material, which is particularly unfavourably orientated towards the impinging ion beam. If the crystal structure and composition of areas close to the surface of such specimens need to be characterised, protective layers may be used. However, those layers, depending on the applied deposition technique, may interact with the sample surface as well thus affecting the results of the analysis. In the work presented here, the possible interactions which might occur between the various protective coatings of ion-beam deposited Platinum, electron beam deposited Platinum, Silicon Oxide or adhesively bonded Gold foil and the subsequent FIB-preparation of the oxide layers on Ni-Ti alloys are investigated, with respect to and how these might affect the TEM-images obtained of areas close to the surface of such specimens. It is shown that the use of adhesively bonded Gold foil as a protective coating, in particular, permits comprehensive characterisation of the surface, including the use of high-resolution TEM, to be carried out, up to the surface of the Oxide layer itself.

Single Femtosecond Laser-Pulse-Induced Superficial Amorphization and Re-Crystallization of Silicon

“…Cross-sections perpendicular to the surface were characterized by HRTEM and STEM-EDX combined with an energy dispersive X-ray spectroscopy system at a spot on the Si<111> wafer irradiated at E p = 12 µJ ( ϕ 0 = 0.24 J/cm 2 ). Surface-preserving sample preparation for TEM was carried out using focused ion beam (FIB) milling and an in-situ lift-out technique [ 55 ]. The preparation of the TEM lamella started by the deposition of a protective Pt capping layer at the region of interest (ROI).…”

Chemical effects during the formation of various types of femtosecond laser-generated surface structures on titanium alloy

“…The potentially most powerful but most time-consuming analytical method is transmission electron microscopy (TEM), where in the first step a cross-sectional lamella of the region of interest at the surface has to be prepared by deposition of a protecting capping layer followed by focused ion beam etching. In the second step, after subsequent milling of the lamella to electron beam transparency, direct electron beam-based imaging or diffraction can be applied to visualize the subsurface region, for identifying chemical elements or to reveal crystalline or amorphous regions [32].…”