Degrees incorporating this pedagocial element :
Description
Goal: Introduction to local probes techniques in the field of nanosciences and nanotechnologies.
Content
1. Introduction to Scanning Probes Microscopy (1h30)
- Comparison between surface analysis techniques: SEM/TEM, SFA
- Presentation of the SPM sub-families: STM / SFM / SNOM via examples of applications
2. The Scanning Tunneling Microscope (7h)
- The tunneling effect
- STM relevant parameters
- Expression of the tunneling current
- The STM instrument
- Tip fabrication methods
- Electronic and instrumental chain to measure and control tunnelling current in the pico/nano-ampere range ADC/DAC, I/V converter, lock-in amplifier
- Source of noises and detection limit
- Vibration isolation (tutorial on transfer function and damping)
- Measurement at low temperature : how to operate an STM in a cryostat>
- Operating STM modes and associated measurements
- Local density of states (LDOS) and I/V spectroscopy
- Constant current mode versus constant height mode
3. The Atomic Force Microscope (12h)
- Why mechanical oscillators
- Introduction and history
- Mechanical susceptibility
- Limits of sensitivity (readout noise and Brownian motion)
- Working at resonance, decrease the size/mass
- How to build an AFM
- Micro fabrication of cantilever and tips
- Nano positioning (piezo material and issues with them as hysteresis…)
- Precision position measurements (optical and capacitive)
- Signal analysis (Homodyne detection, PLL and PID)
- Operating AFMs
- Calibration process (cantilever stiffness, position detection)
- What physical values are accessible (van der Waals, electrical, magnetic, friction forces)
- Different modes of operation
- Maps analysis and image processing
- Surface analysis parameters: rms, ra, skewness, kurtosis, etc
- Artefacts, tip dilation effect
- Tilt correction via polynomial subtraction and color scale
- Tutorial on processing of the images and spectroscopy curves obtained in PW via Gwyddion software