Approaches for Sample Characterization and Lithography with Nanoparticles using Modes of Scanning Probe Microscopy

Abstract

Measurement and imaging modes of scanning probe microscopy (SPM) have been routinely applied for characterizing systems of nanoparticles; however the evolution of fabrication methods to prepare arrangements of nanoparticles remains a challenge. Reproducible fabrication of surface structures which integrate nanoparticles within ultra-small patterns will require innovative approaches to achieve high throughput and precision. Strategies for nanoscale lithography have been introduced for preparing defined arrangements of nanoparticles on surfaces based on physical or chemical interactions. For example, physisorption was employed for attaching nanoparticles based on colloidal lithography and site-directed assembly. Microfabricated atomic force microscope (AFM) tips with capillary channels have been used to pattern nanoparticles through electrostatic interactions. Specific chemical interactions can be designed for patterning nanoparticles with dip-pen nanolithography and SPM-based fabrication. Studies with nanoparticles are reviewed, which have applied either in situ and ex situ approaches for imaging and measurements using modes of SPM. The imaging principle for contact and tapping modes are described with example studies of nanoparticle patterns. The SPM modes for measuring physical properties (e.g. magnetism, softness, conductance) using force modulation microscopy (FMM), magnetic force microscopy (MFM), magnetic sample modulation (MSM), and conductive probe AFM are described for selected studies of lithography with nanoparticles. Strategies for patterning nanoparticles using lithography modes of nanoshaving, dip-pen nanolithography, and tip-induced oxidation have been reported for a range of nanoparticle systems. Applications for nanotechnology will require the integration of nanoparticles within engineered surface architectures. Stable, organized arrangements of nanoparticles with robust chemical/physical attachment to surfaces will be needed for applications, to fully gain advantages of the characteristic quantum properties of nanoparticles.