STM
Scanning Tunneling Microscopy

Characterisation Installation 4
add to your wishlist in your wishlist (remove)

Scanning tunneling microscopy (STM) allows imaging conductive surfaces at the atomic scale. It is possible to characterize the distribution of surface terraces and steps, as well as to determine the atomic arrangement of (ordered) surface (over)structures.

In STM, an atomically sharp tip is scanned on a surface at a few-angstrom distance, while a bias voltage is applied between these two electrodes, so that a current flows due to the quantum tunneling effect. The intensity of the tunneling current depends exponentially on the tip-surface distance and can therefore be used to reconstruct a morphologic image.

STM is a local technique: while high-resolution can be achieved on small (nanometer sized) areas, information on large-scale (micron sized or more) is lost, and measurements have to be repeated systematically on several regions of the sample to get statistically relevant information.

Due to stability performances, STM experiments are typically time-consuming. The technique is applicable both in air and in vacuum. Ultra-high-vacuum (UHV) is required for the characterization of delicate, atomically clean systems.

The STM signal is not purely topographic, but brings also information on the local density of electronic states. Scanning tunneling spectroscopy (STS) is an extension of STM that provides information about the density of electrons in a sample as a function of their energy. Inelastic tunneling spectroscopy (IETS) is a challenging extension for the investigation of vibrational states at liquid helium temperature. The STM tip can also be used to manipulate single atoms and molecules.

i
@
          provided at NFFA-Europe laboratories by:
Italy
Germany
Switzerland
PSI
Switzerland

Surface Science Lab @ Laboratory for Micro- and Nanotechnology

STM

W-Tip

1pA-1μA, -10V to +10V

pA

0.01Å

4x motors, 0.5μm x 0.5μm

Anything conducting or semiconducting (pA)

UHV

DESY
Germany

Temperature UHV STM/AFM @ DESY NanoLab

Topographic imaging of surfaces 

Omicron UHV STM/AFM instrument

High resolution quartz tuning fork AFM

STM tunnelling spectroscopy

AFM contact and tapping mode

Magnetic Force Microscopy (MFM) option

Sub-atomic resolution in x, y, z by piezo scanner

x-y translation: 10 mm x 10 mm

Sample size: 10 mm x 10 mm

Variable temperature range: 50 K < T < 500 K (liquid N2 and option for He cooling)

10-10- 10-11 mbar base pressure

Access for optical microscope

Direct sample transfer under UHV from and to the UHV system

CNR-IOM
Italy

LT-STM

Characterisation of structural and electronic modifications at the atomic scale

Time resolution: ≥ 30sec/image

Sample size:  ø≤8mm

Sample preparation T range: 30K-1400K

UHV

Gas inlet: ≤10-5 mbar

T range: 2.5K-300K

LEED, QMS, knudsen cells, TPD

Electronic and vibrational local spectroscopy

Single atom/molecule manipulation

CNR-IOM
Italy

VT-STM

Characterisation of structural and electronic modifications at the atomic scale

Time resolution: ≥ 30 s/image

Sample size: ≤ 9 x 7 mm2 x 1 mm or ø ≤ 7 mm x 1 mm

Sample preparation T range: -180°C-1100°C

UHV

Gas inlet: ≤ 10-6 mbar

T range: -120°C - 600°C

LEED, QMS, evaporators

System optimised for high-resolution and in-operando experiments