Atom Probe Tomography (APT)

Atom probe tomography (APT) is a quantitative 3D chemical high-resolution microscope mapping the spatial distribution of elements in a sample in 3D with a sub-nanometre scale.

CAMECA / FLEXTAP laser assisted tomographic atom probe

FlexTAP is a laser-pulse assisted atom probe tomography that gives a 3D chemical quantitative mapping of atoms within a tip-shaped sample in three dimensions with a sub-nanometre spatial resolution. FlexTAP is suitable for elemental composition and morphology characterization such as doping, interface and clustering distribution.

An amplified ytterbium doped laser operating from 1024 to 343nm with a pulse duration of 450fs and 100kHz repetition rate allows the analysis of metallic and semi-conductors samples. The detector is an advanced delay line detector (ADLD) able to detect the 2-D position of multi-ion hits giving reliable composition with a lower limit of detection of around 5×1018at.cm-3. FlexTAP is equipped with electrostatic lenses and flexible field that gives high mass resolution (m/Δm<3000) suitable for nanoscience investigations.


Specifications

  • IR (1024nm)/vis (512nm)/UV (343nm) fs laser pulses (to trigger and assist the field evaporate atoms from the end of a sharp tip)
  • Detection efficiency: ∼62%
  • Field of view: from 8° to 30°
  • Analysed volume: 100 × 100 × 200 nm3
  • Ultra-high vacuum environment
  • Sample based temperature: <80K
  • Depth resolution: ∼0.3nm
  • Lateral resolution: ∼0.5nm
  • Mass resolution: <3000 m/Δm
  • Lower limit of detection: ∼5×1018 at.cm-3
  • Tip-shape sample preparation by focused ion beam for APT analysis. End-radius <50 nm
  • APT reconstructed volume: ∼100 × 100 × 200 nm3

Ascent+ facility
CEA-Leti

Platform Technologies

  • Nano for Quantum Technologies
  • Disruptive Devices
  • Advanced Integration

Key Enabling Technologies

  • Metrology / Characterisation: Physical

Case Study

A researcher develops devices for photonic applications. APT can be used to map and quantify the N and P-type doping in devices with 2D or 3D architectures. The III element site fraction in the optical active region (QWs, QDs) of LED structure can be calculated. The experimental results can be used to simulate the band gap energy and quantum confined states of the LED to give a better explanation of the mechanisms responsible for the quantum efficiency of the LED.

Typical Applications
The typical applications of APT are for the elemental analysis for 2D and 3D structured materials or devices with a detection limit as low as 5×1018 at.cm-3 at a subnanometer scale.

Key Enabling Capability

Metrology / Characterisation

Platform Technology

Advanced Integration, Disruptive Devices, Nano for Quantum Technologies

Facility

CEA-Leti