KEY FEATURES
The SPECS LEEM instrument FE-LEEM P90 AC is a next generation Low Energy Electron Microscope with integrated aberration correction, showing astonishing 2 nm resolution for dynamic LEEM microscopy experiments. With this instrument, based on the design of Dr. Rudolf Tromp, nanometer scale processes on surfaces can be observed in real-time.
Guiding the design of the SPECS FE-LEEM P90 was the goal to achieve an extremely high resolution with a minimum number of electronoptical elements.
In order to achieve this incoming and outgoing electrons are separated by a 90° magnetic prism array. This geometry allows a simple, intuitive step by step adjustment of all lens parameters. The magnetic prism transfers both the LEEM image and the LEED pattern astigmatically, allowing routine switching between real image and diffraction. Both image and LEED pattern are transferred without the negative effects of chromatic dispersion, offering superior image and diffraction capabilities.
A sophisticated energy filter enables imaging with an energy resolution down to 250 meV with a minimal impact on the high spatial resolution of the instrument.
The FE-LEEM P90 is integrated into a UHV LEEM sample analysis chamber with facilities for sample preparation and in-situ high temperature sample processing.
Performance
| Lateral Resolution | 3 nm Guaranteed, 1.6 achievable (LEEM) |
| Energy Resolution | < 250 meV (Spectroscopy) |
| Field of View | 800 nm - 100 µm |
| Base Pressure | < 2x10-10 mbar |
| Sample Temperature | RT - 1500 K |
| Spot Size | < 40 µm - < 200 nm |
| Lateral Stability | < 5 nm |
| Lateral Reprodicibility | < 500 nm |
Operation
| Magnification | 400x - 5000x |
| Kinetic Energy Range | 0-1000 eV |
| Extraction Voltage | 2 keV - 15 keV |
| Electron Gun | Cold Field Emission Gun |
Mounting
| Energy Filter | 90° Magnetic Prism |
| Slits/Apertures | Integrated Contrast and Field Apertures |
| Sample Holder | SPECS SH2/12 |
| Aberration Correction | Additional 90° Magnetic Prism |
AC FE-LEEM P90 Double Stage Results
This application note shows results obtained with the SPECS FE-LEEM P90, measured at the Kamerlingh Onnes Laboratory at the University of Leiden in April 2011. The sample is graphene on SiC.
The crystallinity of graphene flakes and their orientation with respect to the Cu(111) substrate are investigated by means of low-energy electron microscopy (LEEM). The interplay between graphene and the metal substrate during…
Generally, it is supposed that the Fermi level in epitaxial graphene is controlled by two effects: p-type polarization doping induced by the bulk of the hexagonal silicon carbide (SiC)(0001) substrate and overcompensation by…
Charge transport measurements form an essential tool in condensed matter physics. The usual approach is to contact a sample by two or four probes, measure the resistance and derive the resistivity, assuming homogeneity within the…
