Surface acoustic wave-assisted scanning probe microscopy—a summary

Abstract

Elastic properties of nanoscopic materials, structures and thin films are important parameters controlling their growth, as well as their optical and electronic properties. Acoustic microscopy is a well-established method for elastic imaging. In order to overcome its micrometer-scale diffraction-limited lateral resolution, scanning probe microscopy-based acoustic near-field techniques have been developed. Among the acoustic modes used for microscopy, surface acoustic waves (SAWs) are especially suited for probing very small and thin objects due to their localization in the vicinity of the surface. Moreover, the study of SAWs is crucial for the design of frequency filter devices as well as for fundamental physical studies, for instance, the probing of composite fermions in two-dimensional electron systems. This review discusses the capabilities and limitations of SAW-based scanning probe microscopy techniques. Particular emphasis is laid on the review of surface acoustic waves and their interaction with elastic inhomogeneities. Scattering, diffraction and wave localization phenomena will be discussed in detail. Finally, the possibilities for quantitative acoustic microscopy of objects on the nanoscale, as well as practical applications, are presented.

Interferometric imaging of nonlocal electromechanical power transduction in ferroelectric domains

“…It is tempting to interpret the MIM-Re fringes as the standingwave patterns of the acoustic displacement fields underneath the tip, similar to those measured by scanning laser vibrometry (30,31), scanning electron microscopy (32,33), and scanning probe microscopy (34,35). However, should the data represent a standing-wave pattern due to strong reflection off a DW, as suggested by an earlier MIM work (36), the measured periodicity would indicate the dominance of a guided wave with an extraordinarily large phase velocity of 8.8 km/s.…”

Single-Input and Multiple-Output Surface Acoustic Wave Sensing for Damage Quantification in Piezoelectric Sensors

“…Using a spin-coater, thickness variation within the preferred area can be controlled by adjusting the spin speed, time, and viscosity of the liquid. Variations in material properties such as surface and bulk defects lead to wave scattering, magnitude-dependent conversion of energy from fundamental to harmonic frequencies in a nonlinear medium, or losses due to viscous contaminants on the surface [ 64 ]. The size of the deposit is much bigger than the wavelength of the monitored acoustic waves.…”

Acoustic Scanning Probe Microscopy: An Overview

“…Nevertheless, if the diffracting features are at the interface or under but in proximity to the surface investigated by AFM, the tip can be used as a mechanical probe to collect the evanescent-but not yet extinguished-diffracted waves. In practice, the unique lateral resolution enabled by SPM techniques suggested to employ both AFM [18,19] and STM [20][21][22] for studying SAWs propagation and related phenomena (reflection, mode conversion, diffraction, scattering, interaction with elastic inhomogeneities at nanoscale) [23]. Use of SPM probes for detecting evanescent acoustic waves is the same idea that led to scanning near-field optic microscopy (SNOM) [17,[24][25][26], where AFM is used for collecting diffracted evanescent electromagnetic waves from nanometrical objects.…”