Course description The course is largely experimental (40% at least of the total time is devoted to laboratory activities) and intends to give the students basic and advanced information on the large number of Scanning Probe Microscopy (SPM) techniques presently available for the physical, chemical, electromagnetic, optical and thermal characterization of the surfaces of materials down to the nanometer or atomic scale. The various operating modes of SPM instrumentation will be described in detail, as well as the practical tips for the realization of microscopy (and spectroscopy) measurements in insulating, conducting, semiconducting, biologic and magnetic samples, mainly by means of Scanning Tunneling Microscopy (STM), Atomic Force Microscopy (AFM), Conducting AFM (CAFM), Scanning Thermal Microscopy (SThM) and Kelvin Probe Force Microscopy (KPFM). The most important methods for the analysis of topographic and spectroscopic images will be also described and applied in order to obtain information, for example, on the roughness and superficial quality of samples, on the crystal structure and defect distribution at atomic level, on the creation and manipulation of nanostructures or on the determination of the electronic density of states of semiconducting, metallic and superconducting materials. Expected Learning outcomes After this course the student will be able, on one side, to correctly understand the data obtained by an SPM microscope and described in the literature, with particular emphasis to the high care that must be used in order to obtain accurate SPM measurements and to the deviations from ideality (defects) present in all the measurement and how they can be corrected or, at least, reduced by hardware and/or software tools. On the other side, the student, in principle, will be able to operate (under a light supervision) a scanning probe microscope successfully, at least in the basic contact and tapping AFM modes.

Useful (but not mandatory) prerequisites are the basics of: Mechanics (free and forced harmonic oscillations, the energy of a force field, elastic forces, etc.), electromagnetism (electric and magnetic forces and energies), quantum mechanics (wave function, observable quantities, uncertainty principle, tunneling phenomena) and solid-state physics (van der Waals force, properties of insulating, semiconducting and conducting materials, etc.)

Course Topics 1. Generalities on Scanning Probe Microscopy; Components of SPM instrumentation; Tunneling microscope (STM); Tunneling current (with equations); Resolution of STM; Scanning tunneling spectroscopy (STS); Examples of Scanning Tunnel Microscopy and Spectroscopy (in metals, semiconductors and superconductors). 2. Principles of Atomic Force Microscopy: Generalities, Van der Waals force and tip-sample interaction force (with calculations), parts of the instrumentation, measure of the deflection of the cantilever (optical lever), scanning modes: Contact mode, noncontact modes (with calculations of the resonant frequency of the cantilever, coupling with tip-sample interaction force, dependency of the resonance parameters from dF(z)/dz), tapping mode and examples. 3. Curves F vs. z; Types of tips and cantilevers; STM e AFM examples in different materials (metals, alloys, semiconductors, insulators, polymers, biological samples, atomic resolution with STM and atomic periodicity with AFM). 4. SPM techniques and instrumentations of different kind for the measurement of dif-ferent signals: Lateral forces, force modulation, phase-contrast imaging, magnetic forces, electrostatic forces (Kelvin probe microscopy), scanning thermal microscopy (SThM), nano thermal analysis (nanoTA), Scanning Near-Field Optical Microscopy (SNOM), Conducting AFM (CAFM), etc. 5. Special SPM techniques: PeakForce Tapping technology and high-speed frequency-modulation noncontact AFM with atomic resolution. Nanolithography using SPM techniques: STM nanolithography, displacement of individual atoms and molecules, conductive AFM tip (local oxidation), AFM nano manipulation, Nanoindentation, dip pen nanolithography, multi-tip arrays, SNOM writing, etc. 6. Piezoelectric scanners: their functioning and their defects; AFM cantilevers and their realization; software and hardware correction of defects; artifacts related to the shape of the tip, tip convolution and deconvolution. Artifacts due to the feedback, vibration isolation and noise monitoring, software and hardware filtering. 7. Functionalities and use of the programs SPIP and Gwyddion for the visualization and the analysis of SPM data and images. Examples of image elaboration. 8. Laboratory activities on: • Calibration of SPM instrumentation along the z-axis and the xy plane. • AFM topography (contact and non-contact mode) in insulating and conducting samples at nanometric and atomic scale. Lateral-force imaging (LFM) and phase-contrast imaging (PCM). • STM topography in conducting samples at nanometric and atomic scale and Scanning Tunneling Spectroscopy (STS). • Force Modulation Microscopy (FMM) and Nanoindentation (force vs. distance curves). • Conductive AFM (CAFM). • Nano Thermal Analysis (nano-TA) and Scanning Thermal Microscopy (SThM) at the nanoscale. • Kelvin Probe Force Microscopy (KPFM) for high resolution surface potential measurements at the nanoscale. • AFM in contact and tapping mode (amplitude and phase contrast) on samples of various kind proposed by the students. Reading Material - Lecture notes of the course (in the form of several pdf and powerpoint files by R. Gonnelli) - V.L. Mironov, Fundamentals of Scanning Probe Microscopy, Institute of Physics of Microsctructures, Russian Academy of Sciences, Nizhniy Novgorod, 2004 (supplied by R. Gonnelli) - Bert Voigtländer, Scanning Probe Microscopy, Springer-Verlag, Berlin Heidelberg, 2015

On site

Oral presentation

P.D.1-1 - January