Cameca LEAP 5000XS Atom Probe Tomography
The Cameca Local Electrode Atom Probe (LEAP) 5000XS uses field evaporation of atoms from a needle-shaped specimen to generate three-dimensional (3D) information at near atomic resolution and possessing chemical sensitivity that can reach parts per million. Analysis software that permits the reconstruction of 3D elemental maps allow for rotation of the data sets and amplification of elements with low counts.
Combining APT analysis with sample preparation using electrochemical etching or Focused Ion Beam (FIB) preparation allows for samples ranging from metallic wires and alloys, to semiconductor devices, geological materials, and even some organic materials.
- 3D imaging with atomic scale resolution (0.1-0.3 nm in depth and 0.3-0.5 nm laterally)
- Near 100% ionization of atoms near the surface by either laser or high-voltage pulsing
- Position sensitive detector with high detection efficiency (up to 80%)
- Simultaneous, single ion detection of
- mass to charge ratio
- initial x,y,z position of ion with sub-nm resolution
- Data set collections consisting of millions of atoms producing sensitivities in the parts per million
- Excellent multi-hit detection capabilities
- Fast and variable repetition rate for ultra-high speed data acquisition
For this technique the sample, prepared in the shape of a very sharp tip, is cooled and biased at a high DC voltage (3-15 kV). The small radius of the tip and a high voltage induce a very high electrostatic field at the tip surface, just below the point of atom evaporation. Under laser or HV pulsing, one or more atoms are evaporated from the surface by field effect (near 100% ionization), and projected onto a position sensitive detector (PSD) with a very high detection efficiency (~ 80%, the highest analytical efficiency of any 3D microscopy). The position of the ion impact on the detector allows for the spatial reconstruction of the original position of the atoms on the tip. The detector also uses the time of flight of the ions (time between the laser or voltage pulse and the ion arrival at the detector) to determine the chemical species using mass over charge ratio.
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