Scanning Probe Microscopy (SPM)
The scanning probe suite comprises a variety of instruments with complementary capabilities that enable the measurement of sample topography down to atomic resolution, spectroscopy of local electronic structure, and nanomechanical properties.
Atomic Force Microscopy (AFM)
AFMs are available for scanning in air, liquids or vacuum with a wide variety of imaging and measurement modes, plus nanomanipulation. All instruments have sub-angstrom vertical resolution (lateral resolution is generally limited by the tip geometry, not the instrument).
Instrumentation for Atomic Force Microscopy:
- Asylum Research MFP-3D AFM (2 instruments) | 0014 Materials Research Laboratory
These two AFMs from Asylum Research are state-of-the-art systems featuring closed-loop, low noise, high precision scanners, with fluid cell, sample heater, Q-controlled AC modes (with phase imaging), conductive AFM, piezo response imaging, contact mode with lateral force, and detailed force-distance measurements. These systems allow scanning in air or liquid environments, and have extensive nanomanipulation and nanolithography capabilities. Maximum lateral scan size on these instruments is 90 µm x 90 µm, and maximum vertical range is 15 µm .
- Asylum Research Cypher | 0014 Materials Research Laboratory
The Cypher is a state-of-the-art AFM from Asylum Research, featuring exceptionally low noise and fast scanning capabilities in addition to advanced scanning modes in air or liquid environments. Maximum lateral scan size on this instrument is 30 µm x 30 µm, and maximum vertical range is 5 µm.
(217) 244-2969 (office)
AFM tip distributors
NOTE: Commonly used tips and sample supplies are available for purchase in the MRL storeroom.
I most commonly use BS-Tap300Al tapping tips from BudgetSensors (very inexpensive but good), and for extra sharp tips, SuperSharpSilicon from Nanosensors. Both of these are carried in the storeroom and can be charged to your University of Illinois account if you have one.
Some other good sources of AFM tips:
- Nano and More USA, US distributor for BudgetSensors, NanoWorld and Nanosensors.
- Ted Pella, Inc., another distributor for BudgetSensors tips and other microscopy supplies.
- Asylum Research, distributors for Nanosensors and Olympus.
- Nanoscience Instruments, US distributor for VistaProbes, plus carbon nanotube tips (and a great resource for nanoscience educators).
- MikroMasch, many types, including the Hi-Res one nanometer tips.
- Novascan Technologies, functionalized tips with defined chemistries.
Scanning Tunneling Microscopy (STM)
STM instruments are available for work in conditions ranging from ambient atmosphere to ultrahigh vacuum. Atomic resolution is achievable on all of the STM systems. All samples for STM must be at least somewhat electrically conductive.
Instrumentation for Scanning Tunneling Microscopy:
- Asylum Research Cypher STM | 0014 Materials Research Laboratory
STM mode on the Cypher serves in part as a testbed for determining whether STM is a viable experimental technique for samples before investing effort into UHV STM measurements. Additionally, the ambient conditions on this instrument permit STM measurements of samples which may not respond well to vacuum environments.
In Scanning Tunneling Microscopy (STM), an electrically biased tip is scanned across a surface at a very close distance (about an atomic diameter). The current flow between the tip and the sample (due to quantum tunneling) strongly depends on the tip-surface gap and can be measured with great accuracy. This changing current signal can in turn be used to generate a surface topography map. Density of (electronic) states spectroscopic measurements are performed by sweeping the bias through a range of voltages and measuring the current response. This method only works with conducting samples, e.g., metal, graphite, semiconductors. Atomic-scale topographic resolution is common.
Information regarding the Sloan Dektak3 ST stylus surface profilometer can be found at http://mrl.illinois.edu/facilities/center-microanalysis-materials/cmm-in....
Information regarding the Hysitron TI-950 TriboIndenter for nanomechanical property measurements can be found at http://mrl.illinois.edu/facilities/center-microanalysis-materials/cmm-in....