XSTM

XSTM and low-temperature STM of nanostructures

instrumentation

The laboratory operates a room-temperature ultra-high vacuum (UHV) scanning tunneling microscopy STM) system equipped with fast entry lock, sample and tip preparation chamber, LEED, Auger spectrometer, evaporators, cleavers, ion gun, etc. The residual pressure during image acquisition is 7 x 10 ^-11 torr. The figure at the right shows the STM system. Another system, containing a high-resolution electron energy loss spectrometer, an electron energy analyzer for photoemission spectroscopy, a He lamp, and other facilities for sample preparation, is used to characterize some of the samples.

Recently we have successfully tested a second home made low temperature scanning tunneling microscope (LT-STM) system that can be operated between 5 K and 300 K in ultra high vacuum (UHV). The images shown below have been taken with this system at 55 K and 5 K.

The home made STM head is held in a double cryo-shield at the bottom of an UHV-compatible liquid He cryostat. The sample can be prepared on a manipulator which can be cooled by liquid nitrogen or helium, so that it can be inserted in the STM head without breaking the vacuum or rising its temperature. The STM tip can be changed without breaking the vacuum.

The STM system is located on an isolated concrete block in a sound isolation cabin. The UHV preparation chamber hosts an electron energy analyzer, a LEED system, evaporators, and electron and ion guns. The liquid He cryostat and the STM head have already been used to obtain new scientific results on the insulating ground state of Sn/Si(111)-(sqrt(3) x sqrt(3)) (S. Modesti et al., Phys. Rev. Letters 98, 126401 (2007)).

Click here to see a brief description of the new system. Or have a look at some pics of the new LT-STM system or the construction work in the lab space dedicated to the STM.