Scanning Tunneling Microscopes
A Scanning Tunneling Microscope is a device which is capable of
atomic resolution, and was the subject of a Nobel Prize for IBM
researchers who first demonstrated the operating principle in the early
1980s. Machines which use this principle are now found in most
materials technology and life sciences institutes and companies
However, researchers in materials technology frequently need to
provide particular environments for their samples while taking STM
images. In particular, it is often required to alter the
temperature of the sample, and ensure an ultra-high vacuum to maintain
atomic-level cleanliness of the sample surface.
Working with Oxford Instruments, we provided both team and project
management and key technical innovation which led to the introduction of
The first of these was a variable-temperature STM, incorporating both
a cryostat and a sample heater to enable the temperature to be varied
from 20K to 1000K. All piezo-electric positioners in the design
were at room temperature. Technical innovation was provided in the
anti-vibration system and the thermal design to meet the overall design
goals. The core of the STM design was established through
collaboration between WA Technology and the FOM Institute.
The second STM was a low-temperature machine, capable of cooling to
6K in UHV. The key difference as compared to the VTSTM above was
the need to select an area to be scanned anywhere in a 6mm square.
Also, all the piezo-electric positioning systems were at 6K or lower to
ensure an isothermal environment for the sample. These constraints
(i.e. the coarse positioning and isothermal specification) placed on the
design led to an extremely cramped parameter space in terms of design
philosophy and materials choice. Team recruitment and leadership,
and key innovation was provided in the anti-vibration and cooling
systems to provide a system which met all the design goals.