Mönch

High throughput and high efficiency cathodoluminescence add-on for STEM

The Mönch is a cathodoluminescence detector for STEM that has been designed from the ground up to achieve unprecedented signal-to-noise ratio and spectral resolution.

Mönch-Attolight-STEM-Cathodoluminescence-Detector-Defect-Inspection

It is used by demanding researchers who want to measure simultaneously ultra high-resolution images and hyperspectral maps of individual nano-particles, quantum dots or atomic defects. The design behind the Mönch has a solid publication track record, which includes reports on nano-plasmonics, quantum nano-optics, simultaneous measurements of cathodoluminescence and EELS, non-linear spectroscopy of individual quantum wells and more.

When acquiring a cathodoluminescence map in your STEM, it is crucial that you reach the desired signal-to-noise ratio in the shortest amount of time possible, so that you can generate images with a large number of pixels. Yet, you can only achieve ultrahigh resolution with weak probe currents, leading to weak cathodoluminescence emission. As a result, the ideal cathodoluminescence detector is bound to achieve the impossible: it should collect photons over an extensive solid angle and fit in the small gap between your sample and the pole pieces of your STEM ; it should also preserve brightness, spectral resolution and collection efficiency over large scanning areas.

The Attolight Mönch achieves all this. First, its collection optics is crafted by our engineers with the utmost care to achieve unprecedented curvature radius and miniaturization level; it is so thin that it can be accommodated in most aberration corrected or analytical STEMs on the market, while maintaining enough degrees of freedom and stiffness to allow for perfect sub-micrometer alignment of the mirror while installed in the STEM. Then, the Mönch collects and couples cathodoluminescence directly into a fiber bundle and carefully preserves the intensity of the signal throughout a spectrometer, so that constant spectral resolution is achieved. Finally, an ultrafast EMCCD camera measures the signal and generates massive hyperspectral maps in seconds. Data can be directly acquired and visualized in your favorite acquisition software in parallel with other techniques (EELS, EDS, etc.).

The Mönch is not just another add-on. It is a solution developed by a company that builds electron microscopes and has years of expertise in optics and spectroscopy. Attolight took all the know-how it acquired designing and manufacturing dedicated cathodoluminescence scanning electron microscopes and brought it to STEMs.

The Mönch includes a proprietary actuated collection mirror for fast and perfect optical alignment, a fiber coupled spectrometer for high resolution spectral analysis, a scientific grade high speed camera for fast hyperspectral data acquisition, as well as a hyperspectral optimized scanning module for optimal control of the STEM beam.

Key benefits


  • Brightness conservation from emission to detection
  • Constant spectral resolution (no trade-off with intensity)
  • Sub-micrometer precision mirror actuators with three degrees of freedom to achieve perfect collection efficiency at any position on the sample
  • Full sample area can be investigated
  • Fits within a 2 mm gap between the sample and the pole piece (contact Attolight to learn about the compatibility of your system)
  • Ultrafast cameras and scanning unit for millisecond hyperspectral imaging in the UV, visible and NIR
  • Retractable mirror
  • Compatible with most STEMs techniques, such as HAADF, BF, diffraction, EELS (detector inserted) or EDS, tomography (detector retracted)
  • Compatible with Gatan Digital Micrograph

Applications


  • Study of advanced materials, such as : Nitrides (GaN, InGaN, AlGaN, …) ; III-V (GaP, InP, GaAs, …) ; II–VI (CdTe, ZnO, …)
  • Wide band-gap materials (diamond, AlN, BN)
  • Compositional inhomogeneities in compound materials (e.g. Indium clustering in InGaN)
  • Confined structures or heterostructures morphology to their optical properties
  • Defects (vacancies, threading dislocations, stacking vaults, …)
  • Plasmonics

Product Specifications

  • Proprietary reflective mirror
  • Optical coupler for fiber bundle
  • Collection optics optimized for transition from 200 nm to 1.7 μm
  • Fiber bundle to decouple the light optics from the spectral detection and minimize vibrations
  • All numerical apertures match each other in order to keep brightness throughout the device
  • Possibility to couple the cathodoluminescence output to a user optical set-up (e.g. interferometer, light injector, etc.)
  • Possibility to quickly exchange the fiber bundle to adapt to specific user needs (for example light injection or interferometry…)
  • Hyperspectral mapping of cathodoluminescence
  • Dispersive spectrometer with two imaging exits (320 mm focal length) and a 3-grating turret (gratings to be specified by the customer at time of order)
  • High speed EMCCD camera for UV-Visible or high speed CCD camera for UV-NIR
  • InGaAs linear array for NIR (optional)
  • 3 degrees of freedom for arbitrary movement of the mirror relatively to the sample
  • Automated retractable mirror
  • Travel range: +- 150 μm (Z), 3 mm (X), 100 mm (Y)
  • Smallest increment: 50 nm
  • Repeatability (full travel range) : 1 μm
  • Touch security to avoid damaging the pole piece or
    sample holder
  • External scanning card with: 4 inputs (12 bits) for additional single channel detectors (PMTs, …) ; 2 outputs for controlling the STEM scan (X and Y) ; 1 output for blanking the STEM beam
  • Fastest measurement speed: 900 Hz (18 s for a 128 Å~ 128 map)
  • Control software compatible with Windows. 7, 64 bit
  • Acquisition and visualization module for Gatan Digital Micrograph
  • STEM with at least 2.5 mm gap between the specimen and the pole piece (the total gap for a symmetric pole piece must be 5 mm). Smaller design on request
  • Sample holder with less than 300 μm between the sample surface and its holder (most commercial sample holders can be adapted by Attolight to achieve theses specifications)