USM1800 Cryogen-Free Low Temperature UHV Scanning Probe Microscope

PDF SPM System Specs. Published Papers

Realization of STM with atomic resolution below 6K by mechanical refrigeration
Continuous cooling for long periods of time without the use of scarce liquid helium

Image of USM1800

The new closed-cycle USM1800 LT UHV SPM is now part of the UNISOKU SPM product family! The USM1800 provides sample temperatures below 6K, and the cryogen-free cooling system achieves ultimate SPM performance at low temperature while allowing interruption-free measurement conditions.


  • Sample temperature below 6K (when optical window shielding is closed)
  • State-of-the-art SPM platform with atomic resolution imaging (qPlus AFM is available as an option)
  • Optical access and in-situ deposition capabilities (inertial-driven lens stages on the SPM platform are available as an option)


  • Upgrades for LT-STMs with liquid He reservoir possible
  • Observation of quasi-particle interference patterns by tunneling spectral mapping
  • Observation of surface adsorption structure using in-situ deposition capabilities
  • Studies of photo-induced phenomenon in combination with simultaneous SPM measurements

Schematic view of the USM1800 system

3D model of sample/probe transfer

Cooling performance

Cooling time: <6K in 24 hours

Cooling performance Cooling time: <4K in 24 hours

Temperature stability @ 5.2K

Cooling performance Temperature stability @ 5.2K

Long time stability of STM

STM image (Vs=+300mV)

Long time stability of STM STM image (Vs=+300mV)

dI/dV mapping (20mV)

Long time stability of STM dI/dV mapping (20mV)

All pixel STS measurement during STM imaging. On HOPG
condition : 35hours per a flame

Drift rate : < 1nm/35hours

Tunneling current noise spectrum

Nc-AFM NaCl atomic image at 6K sample

Superconducting gap of Pb

STM Au(111) atomic image at 5.6K sample

Nc-AFM NaCl atomic image at 6K

Nc-AFM NaCl atomic image at 6K sample

Sample: NaCl (100)
AFM sensor: q-Plus
amplitude: 200pm
Frequency shift: -13Hz

STM Au(111) atomic image at 5.6K

STM Au(111) atomic image at 5.6K sample

Sample: Au (111)
Scan size 7nm x 7nm
Bias voltage +5mV,
Tunnel current 1nA

SPM structure Tip scanning type
Coarse positioning for X,Y (ø 1 mm) and Z (5 mm)
Scan range 1um × 1um at 6K
Sample holder Bayonet type (DC heating, EB heating, cleaving)
Temperature <6K
1.5 year in each for Maintenance
(Pulse tube refrigerator)
Options Internal optical lens stages with 3D coarse positioning (NA~0.25)
Tuning Fork NC-AFM
Chamber structure Includes SPM observation chamber, preparation chamber, and loadlock chamber.
In-situ UHV sample/probe holder transfers
Laboratory Requirements
Recommended laboratory area Floor space: 4m × 4m, Ceiling height: ø2.8m
Floor vibration level <1μm/s (rms) below 5Hz
<3μm/s between 5-10Hz
5μm/s above 10Hz
Preparation of equipment •Cooling water
•Three-phase electric power

PDF SPM System Specs.