attoAFM III

tuning-fork based atomic force microscope

tuning fork based AFM sensor with wire-type tip

high Q-factor for high sensitivity

closed loop scanning (optional)

easy retrieval of regions-of-interest

non-optical deflection detection

scanning gate microscopy on 2DEGs down to mK

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The attoAFM III is an atomic force microscope designed particularly for applications at low and ultra low temperature. Due to the non-optical shear force detection based on a tuning fork, this system is ideally suited for applications where input of light is problematic, either because of light-sensitive samples, or due to the additonal heat load and power dissipation generated by a laser based deflection detection system. A typical application of the attoAFM III microscope is scanning gate microscopy (SGM) on semiconductor structures. This microscope is compatible with wire-type tips glued onto one prong of a small quartz tuning fork as well as with commercially available tuning forks with integrated tips. The decrease in the horizontal oscillation amplitude due to tip-sample interaction when approaching the sample is monitored and/or used as a feedback signal. The force resolution of this technique is typically 0.1 pN.

The attoAFM III is available with an optional interferometric encoder for closed loop scanning. The microscope uses a set of xyz-positioners for coarse positioning of the sample over a range of several mm, and dedicated mechanically amplified piezo based xyz scanners with a very large scan range even at cryogenic temperatures.

For scanning gate microscopy experiments, the attoAFM III can be equipped with a 20 pin chip carrier sample holder, which allows for simultaneous transport measurements while imaging to explore the effect of a movable local gate onto the current flow in the mesoscopic device under investigation.

Last but not least, due to the open signal architecture of our powerful and flexible ASC500 SPM controller, the needs of experts are addressed to have control over all signals, while maintaining a very user-friendly software interface that also supports measurement routines based on LabVIEW scripts. All in- and output signals are accessible via front panel BNCs, and can hence easily be monitored, stored and used for additional control loops or spectroscopies. Finally, our unique closed loop scan option allows for global sample navigation over the complete range of the microscope at cryogenic temperatures, and hence enables the retrieval of regions of interest very precisely. For more info please refer to the fundamentals section.

Cryogenic Tablet

Specifications

Resolution
z bit resolution @ 4 K7.6 pm at 2 µm scan range
measured z-noise density< 16 pm/√Hz
Sample Positioning
total travel range5 x 5 x 5 mm³ (open loop)
step size0.05..3 µm @ 300 K, 10..500 nm @ 4 K
fine scan range50 x 50 x 4.2 µm³ @ 300 K, 30 x 30 x 2 µm³ @ 4 K (open loop)
sample holderASH/QE/0 quick exchange sample holder and integrated heater with calibrated temperature sensor
Suitable Operating Conditions
temperature range1.5 K..300 K (dependent on cryostat); mK compatible setup available on request
magnetic field range0..15 T+ (dependent on magnet)
operating pressuredesigned for He exchange gas (vacuum compatible version down to 1E-6 mbar on request)
Suitable Cooling Systems
titanium housing diameter48 mm
bore size requirementdesigned for a 2" (50.8 mm) cryostat/magnet bore
compatible cryostatsattoDRY1000/1100/2100, attoLIQUID1000/2000/3000/5000
Compatibility with Electronics
scan controller and softwareASC500 (for detailed specifications please see attoCONTROL section)
Options and Upgrades
closed loop scanning & global sample coordinatesinterferometric encoders for scan linearization and closed loop sample navigation
ultra-large scan range upgrade80 x 80 µm² @ 300 K, 125 x 125 µm² @ 4 K
in-situ inspection opticstip/sample monitoring via in-situ LT-LED for illumination, mirrors, lenses and CCD camera (outside), field of view approx. 3 x 2 mm, resolution approx. 20 µm (depending on cryostat)
closed loop upgrade for coarse positionersresistive encoder, range 5 mm, sensor resolution approx. 200 nm, repeatability 1-2 µm
sample holder upgradeASH/QE/4CX quick-exchange sample holder (8 electrical contacts, integrated heater & T-sensor)
General Specifications
type of instrumenttuning-fork based AFM with shear-force or standard detection
sensor head specificsetched metal wires, etched or pulled optical fiber probes, STM tips, Akiyama probes (also compatible with NaugaNeedles commercial tips)
Modes of Operation
imaging modesnon-contact mode AFM, EFM, SGM
slope compensation2 axis scan plane correction
z feedbackPI feedback loop for amplitude modulation (AM), phase modulation (PM) or frequency modulation (FM) using included PLL, constant force
optional upgradesAFM/STM mode
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Customer Feedback

Dr. Stefan Heun NEST

Istituto Nanoscienze-CNR and Scuola Normale Superiore, Pisa, Italy

Directly after the set up in our labs, the attoAFM III in a 3He cryostat - used for scanning gate microscopy experiments - has started to produce great data for us. It runs more than 5 years now, and we have published several papers since then. The instrument worked within specifications from the first day and we really appreciate the excellent attocube support throughout the years!