Scanning probe microscope facility - I
Scanning probe microscopy facility allows researchers to observe and manipulate molecular and atomic level features. This technique helps to study a 3D profile of the surface on a nanoscale.
Make and Model
Agilent, Switzerland, Model: 5500
Available mode for use
Atomic force microscopy-contact, non-contact and tapping mode
Lateral force microscopy-stiffness, frictional forces
Magnetic force microscopy-changes in the phase of the cantilever due to interatomic magnetic force
Scanning tunneling microscopy
Electrostatic force microscopy-Phase response of the cantilever induced by the interaction of the conducting tip and the electrostatic field of the sample surface
Kelvin force microscopy-contact potential difference between tip and sample
Highly modular microscope and scanner
Optional integrated environmental & temperature control
Easy sample access with top-down scanning
Environmental chamber allows imaging in controlled atmospheres. Ports and fittings enable gases, liquids and probes to be introduced to the chamber
- Lateral range X-Y imaging area up to 90μm square; Lateral noise X-Y 0.05nm
- Vertical (Z) range ¡ 8μm; Vertical (Z) noise Level ≤ 0.05nm
Contact Emailspm_mems[at] iitb[dot] ac[dot] in
Nanoindentation Laboratory (at Basement),
Department of Metallurgical Engineering & Material Science,
Powai, Mumbai - 400076
Other contact person(s)
- Prof. Dipti Gupta
Information-External users190.39 KB
Registration form-External users120.09 KB
- STANDARD MODES OF OPERATION
- AFM Contact Mode (ambient (air)
- Non Contact AFM Mode
- Phase imaging
- Force Modulation / Spectroscopy
- STM with low current capabilities
- Magnetic Force Microscopy
- Electric Field Microscopy (EFM)/ Kelvin Force Microscopy (KFM)
- Advanced Electrical Property Measurements including EFM / KFM with the AAC III module (triple lock in AAC module which allows single pass EFM / KFM). For On the first line scan, the AFM operates in normal AC mode. On the second line scan, the tip is lifted a fixed distance from the surface and the tip drive is turned off. The drive is switched to drive an AC bias to the tip. The DC tip bias is controlled by a servo to null the tip deflection due to the potential difference between the tip and sample. More precise correlation between topography / potential information because there is no drift between line scans. This offers, faster results, due to only scanning each line once & stronger effect of potential due to closer proximity to the sample, which can improve signal-to-noise.
- Integrated Environmental Chamber
The EIC mounts directly to the 5500 and provides a sealed sample compartment that is completely isolated from the rest of the system. Eight inlet/outlet ports permit the low of many different gases into or out of the sample area
- Light Source / Detector - Low Coherence laser light source. Detector is a position sensitive photo detector (PSPD) that is optimized for the laser light wavelength.
- Sample Size - upto 20 x 30 x 5 mm
Permits scanning of much thicker sample surfaces, including scanning of non planar and curved surfaces. Samples with thickness upto ~ 5 mm can be mounted.
- Tip Viewing - AFM scanning cantilever/probe optical surface is viewable on axis in real time via Direct Optical Video Access by CCD. The resolution of the device better than 2 microns
- Scanners - The use of a top down scanner - where tip scans from the top, while sample remains stationery. This design is such that it decouples sample from scanning mechanism for protection. Therefore, there is not only isolation of the scanning elements and electronics from the imaging environment to extend life of the instrumentation but also superior sample environmental stability (gases, humidity, temperature, etc) can be achieved for long scanning times. It is a balanced pendulum type scanner design which eliminates artifacts in the images by keeping the relative position of the laser spot fixed in relation to the cantilever through out the scan cycle.
Vertical (Z) range ≥ 8 µm
Lateral range X-Y imaging area up to 90 µm square or larger.
Vertical (Z) Noise Level ≤ 0.05 nm
Lateral Noise X-Y 0.5 nm
- High Resolution STM Scan Head with Low Current Capabilities
- Vertical (Z) range - 0.7 µm
- Vertical (Z) Noise Level - 0.06 rms
- Lateral range X-Y imaging area up to 1 µm square or smaller
- Lateral Noise X-Y 0.03 rms
- Selectable gain switching
the x1 gain medium current imaging with the noise level at 3pA and maximum current at ±10nA.
- Computer / controller and software
Latest Generation Computer System
Controller should have the following minimum specifications
- Data transfer should be via USB link.
- Two Numbers 32 bit floating point Digital Signal Processors (DSPs) should be provided for scan and data.
- Special Lock-in amplifier with adequate frequency range, with true phase and amplitude imaging possibilities.
- Four or more 24 bit DACs for X, Y, Z positioning.
- Eight or more 16 bit data acquisition channels
- Four or more 24 bit DAC outputs.
- Free choice of data points â‰¥ 8012 X 8012 minimal.
- Three configurable lock in amplifiers to allow single pass measurements.
- Capability of higher harmonic imaging upto 6 MHz
- The system should have built in Q control
- Software - Microsoft Windows operating system preferably, supporting TCP/IP for networking. Should provide for customs scripting, customs spectroscopy, scripting capabilities, scripting examples and also scripting functions, so that one can easily design their experimental set up.
- Image processing software
- Highly modular microscope and scanner
- Optional Integrated environmental & temperature control
- Easy sample access with top-down scanning
AFM stands for Atomic Force Microscopy or Atomic Force Microscope and is often called the "Eye of Nanotechnology". AFM, also referred to as SPM or Scanning Probe Microscopy, is a high-resolution imaging technique that can resolve features as small as an atomic lattice in the real space. It allows researchers to observe and manipulate molecular and atomic level features.
How Atomic Force Microscopy works is illustrated in the figure to the right. AFM works by bringing a cantilever tip in contact with the surface to be imaged. An ionic repulsive force from the surface applied to the tip bends the cantilever upwards. The amount of bending, measured by a laser spot reflected on to a split photo detector, can be used to calculate the force. By keeping the force constant while scanning the tip across the surface, the vertical movement of the tip follows the surface profile and is recorded as the surface topography by the AFM.
The predecessor of AFM is STM, Scanning Tunneling Microscopy or the Scanning Tunneling Microscope, was invented in 1981 by G. Binnig and H. Rohrer who shared the 1986 Nobel Prize in Physics for their invention. An excellent technique, STM is limited to imaging conducting surfaces.
Atomic Force Microscopy has much broader potential and application because it can be used for imaging any conducting or non-conducting surface. The number of applications for AFM has exploded since it was invented in 1986 and now encompass many fields of nanoscience and nanotechnology. It provides the ability to view and understand events as they occur at the molecular level which will increase our understanding of how systems work and lead to new discoveries in many fields. These include life science, materials science, electrochemistry, polymer science, biophysics, nanotechnology, and biotechnology
- S. Sarkar, D. Majhi, S. Kurup, Dipti Gupta*, “Photonic Cured Metal Oxides for Low-Cost High-Performance Low Voltage Flexible and Transparent Thin Film Transistors”, ACS Applied Electronic Materials, v4, p2442, (2022)
- Javed Alam Khan, Ajay Singh Panwar, Dipti Gupta, “Domain modulation and energetic disorder in ternary bulk-heterojunction organic solar cells”, Organic Electronics, v102, p106376, (2022) (I.F.)
- J Khan, Ramakant Sharma, Ajay Singh Panwar, Dipti Gupta, “Impact of non-fullerene acceptors and solvent additive on the nanomorphology, device performance, and photostability of PTB7-Th polymer based organic solar cells”, Journal of Physics D: Applied Physics, v55, p495503