atomically-traceable-nanostructure-fabrication

Atomically Traceable Nanostructure Fabrication

Reducing the scale of etched nanostructures below the 10 nm range eventually will require an atomic scale understanding of the entire fabrication process ...

National Institute of Standards and Technology

Using a home-built frictional force microscope that is able to detect forces in three dimensions with a lateral force resolution down to 15 pN, we have studied the energy dissipation between a tungsten tip sliding over a graphite surface in dry contact. By measuring atomic-scale friction as a function of the rotational angle between two contacting bodies, we show that the origin of the ultralow friction of graphite lies in the incommensurability between rotated graphite layers, an effect proposed under the name of "superlubricity" [Phys. Rev. B 41, 11 837 (1990)]].

Superlubricity of graphite.

The origin of adhesion in humid air is investigated by pull-off force measurements between nanoscale contacts using atomic force microscopes in controlled environments from ultrahigh vacuum through various humidity conditions to water. An equivalent work of adhesion (WOA) model with a simplified interface stress distribution is developed, combining the effects of screened van der Waals and meniscus forces, which describes adhesion in humid air and which self-consistently treats the contact stress and deformation. Although the pull-off force is found to vary significantly with humidity, the equivalent WOA is found to be invariant. Increasing humidity alters the nature of the surface adhesion from a compliant contact with a localized, intense meniscus force to a stiff contact with an extended, weak meniscus force.

Origin of adhesion in humid air.

This chapter outlines procedures for sample preparation and the determination of nanoparticle size using atomic force microscopy (AFM). Several procedures for dispersing gold nanoparticles on various surfaces such that they are suitable for imaging and height measurement via intermittent contact mode, or tapping mode, AFM are first described. The methods for AFM calibration and operation to make such measurements are then discussed. Finally, the techniques for data analysis and reporting are provided. The nanoparticles cited are National Institute of Standards and Technology (NIST) Au nanoparticle Reference Materials RM 8011 (nominally 10 nm particles), RM 8012 (nominally 30 nm), and RM 8013 (nominally 60 nm).

Pradeep Namboodiri

National Institute of Standards and Technology

Atomically Traceable Nanostructure Fabrication