Atomically precise electrical probing

At a Glance

The Low Temperature LT NANOPROBE defines a new class of analytical instrumentation that merges SEM navigated nano-probing at LHe temperatures with high performance STM imaging, spectroscopy and manipulation.

  • Four Independent Scanning Tunnelling Microscopes
  • Excellent STM Performance for Spectroscopy and Manipulation
  • 4-Point Transport Measurements on Nanostructures
  • Base Temperature T < 5 K
  • High Resolution SEM Navigation

A major challenge in the development of novel devices in nano- and molecular electronics is their interconnection with larger scale electrical circuits required to control and characterize their functional properties. Local electrical probing by multiple nanoprobes with ultimate STM precision can significantly improve efficiency in analysing individual nanoelectronic devices without the need of a full electrical integration.

In order to meet these requirements the LT NANOPROBE has been developed in collaboration with the Peter Grünberg Institut (PGI) (PGI-6, Prof. C. M. Schneider) at the Forschungszentrum Jülich. As a sophisticated instrument it has been specifically designed for local and non-destructive 4-point probe measurements at low temperatures.

Besides STM probe fine navigation and imaging, the excellent STM performance level of the LT NANOPROBE expands applications to spectroscopic mapping and even the creation or modification of nano-structures by an ultimately precise STM probe. The LT NANOPROBE thus opens up new research opportunities in nanoelectronics, spintronics, and molecular electronics.


Microscope stage design

Omicron´s proven SPM technology has been taken one step further. Cooling the whole microscope to LHe temperatures requires the stage to be extremely compact with only 100 mm in diameter – a real challenge if 4 STM need to be fully functional, independent and highly stable. An efficient thermal shield compartment allows for temperatures well below 5 K, extremely low thermal drift and thermal equilibrium of sample and probes.

In addition, the integration of high resolution SEM navigation requires a small SEM working distance and thus makes a dedicated STM concept indispensable. A sophisticated shared stack scanner allows for a very compact and flat design, while ensuring highly linear, orthogonal and stable STM scanning characteristics. For ultimate STM performance the microscope stage employs an effective eddy current-damped spring suspension


SEM imaging and tip navigation at T < 5 K

For the navigation of four independent STM probes, simultaneous SEM imaging is indispensable to bridge dimensions from the mm-scale down to the nm-scale. The SEM enables a large field of view for probe coarse positioning as well as fine positioning and rapid localisation of nanometer-sized structures with its high resolution capabilities.

As the ultimate tool for that purpose, the UHV Gemini column offers unsurpassed resolution under true UHV conditions. In combination with the Low Temperature UHV NANOPROBE, the in-lens Secondary Electron Detector (SED) represents a key advantage. Only one small access port in the thermal shield compartment of the microscope stage (at T <5 K) is needed thus minimising thermal impact, while still offering a suitable signal for high resolution imaging.

Alternatively, other UHV SEM columns or optical microscopes can cover the lower resolution range if sample structures do not require the ultimate resolution provided by the UHV Gemini column.