Full tip imaging in atom probe tomography

• Published in: Ultramicroscopy Vol. 124; pp. 96 - 101
• Main Authors: Du, Sichao, Burgess, Timothy, Tjing Loi, Shyeh, Gault, Baptiste, Gao, Qiang, Bao, Peite, Li, Li, Cui, Xiangyuan, Kong Yeoh, Wai, Hoe Tan, Hark, Jagadish, Chennupati, Ringer, Simon P., Zheng, Rongkun
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.01.2013
• Subjects: Atom probe tomography; Computer Simulation; Full tip imaging; Image compression; Image Processing, Computer-Assisted - methods; Tomography - methods; Full tip imaging; Image compression; Atom probe tomography
• ISSN: 0304-3991; 1879-2723
• DOI: 10.1016/j.ultramic.2012.08.014

Atom probe tomography (APT) is capable of simultaneously revealing the chemical identities and three dimensional positions of individual atoms within a needle-shaped specimen, but suffers from a limited field-of-view (FOV), i.e., only the core of the specimen is effectively detected. Therefore, the capacity to analyze the full tip is crucial and much desired in cases that the shell of the specimen is also the region of interest. In this paper, we demonstrate that, in the analysis of III–V nanowires epitaxially grown from a substrate, the presence of the flat substrate positioned only micrometers away from the analyzed tip apex alters the field distribution and ion trajectories, which provides extra image compression that allows for the analysis of the entire specimen. An array of experimental results, including field desorption maps, elemental distributions, and crystallographic features clearly demonstrate the fact that the whole tip has been imaged, which is confirmed by electrostatic simulations. ► The full tip has been imaged by atom probe tomography. ► The conductive substrate close to specimen tip introduces extra image compression. ► The apex of the tip is far from a hemispherical shape. ► This work demonstrates a way to increase the FOV of APT.