LT STM_2012
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LT STM Low Temperature UHV STM and AFM Technology • Low Temperature Operation at T < 5 K • Lowest Thermal Drift & Highest Stability • Ultimate STM/STS/IETS Performance • Leading QPlus AFM Technology • Variable Temperature Operation • Guided 3D Coarse Positioning • 50 Hours LHe Hold Time & Fast Cool Down • Safe & Quick Sample/Tip Exchange

Ultimate SPM Atom manipulation with the LT STM - 42 Ag atoms arranged to form the Omicron Logo on a Ag(111) surface at 4.8 K. The parameters were Ugap= -20 mV, IT= 10 nA for imaging and Ugap= -10 mV, IT= 300 nA for atom manipulation, respectively. The probability for atom manipulation was nearly 1 when using these parameters. Measurements by A. Bettac, Omicron NanoTechnology, Germany. 88 2

Performance at 5 K The Omicron LT STM is the first commercial low temperature UHV STM with proven and guaranteed atomic resolution in UHV at 5 K, now with more than 150 units delivered around the world. More than 10 years after presenting the LT STM, the importance of dedicated low temperature SPM techniques in a wide range of active scientific fields is still unbroken. Spectroscopy on molecules, atom manipulation, carbon, superconductors, semiconductors, gases on metals, and magnetics are only a few examples where research takes great advantage of low temperature SPM. The state of reduced...

The Preamplifier Modulation spectroscopy on Au(111) using a superconducting Nb STM tip. The superconducting gap is clearly resolved and corresponds to the BCS value of approximately 2∆ = 2.5 meV at 5 K (fMOD=1967 Hz, VMOD=150 µVPP) . This fundamentally proves the STM tip is in thermal equilibrium with the sample temperature (low temperature QPlus AFM preamplifier active during the measurement). Schematic diagram of the IVC H3 preamplifier. Capacitive compensation and internally switched gain with two feedback resistors. Atomically resolved STM measurement on Si(111) 7x7 surface with a true...

QPlus Sensor 1 mm The QPlus sensor allows for atomic resolution non-contact AFM while maintaining the user-friendliness and known performance level of the LT STM. The ease of use of the QPlus sensor now makes atomic resolution AFM a routine experiment. The sensor employs a quartz tuning fork for force detection in non-contact AFM operation. One prong of the tuning fork is fixed, while the SPM probe tip is mounted to the second prong. It thus acts as a quartz lever transforming its oscillation into an electrical signal as a result of the piezoelectric effect. The feedback signal is based on...

Different System Concepts The MULTIPROBE LT UHV systems are dedicated surface science systems for the low temperature UHV STM. Three standard MULTIPROBE LT configurations are available – S, XP and XA. Each standard system can be used as a base to match the customer’s special requirements. The LT S represents the basic system configuration with the LT STM main chamber and an easy to operate fast entry chamber. Transferring samples and probe tips is made quick and reliable using a UHV wobble stick. The LT XP system is an extended version of the LT S offering a separate chamber for various...

MULTIPROBE LT XP Pos. 4 Pos. 1 Pos. 2 Pos. 3 Pos. 2a The MULTIPROBE LT XP is equipped with a fast entry load lock to introduce samples (or tip transfer plates) into the vacuum system (position 1). A mag probe is used to transfer the sample to position 2. A second mag probe transfers it to a high precision sample manipulator (LN2 or LHe cooling and various heating options available) at position 2a. This position allows extensive sample preparation with system ports configured for sputter sources, evaporators and more. Similar to the LT S system, the second mag probe can also transfer the...

Versatility & Ease of Use Magnetic Fields Variable Temperatures Sample Contacts Based on a magnet coil located behind the sample plate, vertical fields can be generated in the LT STM. The use of superconducting wires avoids heat generation during operation. Coil options for pulsed fields or DC fields are available. The LT STM is equipped with a built-in PBN heater element and a Si diode for temperature measurement. The heater enables quick temperature variation between 5 K to ~ 60 K (LHe operation) and 78 K to ~ 250 K (LN2 operation). The option for 4 spring-loaded electrical sample...

The LT STM Stage Stage Details The LT STM stage has been designed for ultimate STM and AFM performance. It employs a very efficient damping system based on the combination of spring suspension and eddy current damping. This, together with the very rigid scan head design, ensures excellent vibration isolation with a stability in the picometer range. While maintaining its unique performance level, the LT STM has been continuously improved for additional functionality and flexibility. Some examples for the experimental customization possible with the LT STM are: pre-fitted tapped holes at all...

lens holder The LT STM stage is equipped with an easy to operate lifting mechanism. The lifted stage is in direct thermal and mechanical contact with the cryostat, guaranteeing fast cool down as well as easy and safe tip and sample exchange. Once cooled, the stage is released into the eddy current damping system for high-performance SPM experiments. Omicron’s unique design of temperaturecompensated spring suspension allows STM and AFM operation at any accessible temperature from 300 K to 5 K without opening the system for re-adjustment. The patented Omicron piezo inertia drive is based on...

Optical Access & In-situ Evaporation The LT STM has the capability for simultaneous evaporation by two evaporators during STM operation. With the sample facing down, deposition of materials from below becomes possible. In addition, the large Z-coarse range of 10 mm for tip positioning allows for removal of the tip from the evaporation zone. The easy to operate thermal shield compartment consists of two shield pairs for LHe and LN2 shielding, respectively. To minimize heat impact, the shield concept provides three wobble stick selectable configurations: (i) SPM operation with Tmln < 5 K;...