Thermodynamically Stable Colloidal Solids: Interfacial Thermodynamics from the Particle Size Distribution.

True thermodynamic stability of a solid colloidal dispersion is generally unexpected, so much that thorough experimental validation of proposed stable systems remains incomplete. Such dispersions are under investigated and would be of interest due to their long-term stability and insensitivity to preparation pathway. We apply classical nucleation theory (CNT) to such colloidal systems, providing a relationship which links the size-dependent interfacial free energy density of the particles to their size distribution, and use this expression in the fitting of previously reported size distributions for putatively thermodynamically stable nanoparticles.

High-throughput bend-strengths of ultra-small polysilicon MEMS components.

The strength distribution of polysilicon bend specimens, approximately 10 in size, is measured using a high-throughput MEMS fabrication and testing method. The distribution is predicted from reference tests on tensile specimens and finite element analysis of the bend specimen geometry incorporated into a stochastic extreme-value strength framework. Agreement between experiment and prediction suggest that the ultra-small specimens may be at the limit of extreme-value scaling and contain only one strength-controlling flaw/specimen.

Microscale Mapping of Structure and Stress in Barium Titanate.

Cross-correlation of electron backscatter diffraction (EBSD) patterns was used to generate rotation, strain, and stress maps of single-crystal tetragonal barium titanate (BaTiO) containing isolated, small, sub-micrometer domains separated from a -domain matrix by 90° domain boundaries. Spatial resolution of about 30 nm was demonstrated over 5 μm maps, with rotation and strain resolutions of approximately 10. The magnitudes of surface strains and, especially, rotations peaked within and adjacent to isolated domains at values of approximately 10, , the tetragonal distortion of BaTiO.

Electron Reflectometry for Measuring Nanostructures on Opaque Substrates.

Here, we present a method for measuring dimensions of nanostructures using specular reflection of electrons from an electronically opaque surface. Development of this method has been motivated by measurement needs of the semiconductor industry, and it can also be more broadly applicable to any periodic, pseudo-periodic or statistically stationary nanostructures or nanopattern on an opaque substrate. In prior work, it was demonstrated through the presentation of proof of concept experiments and simulated examples that Reflective Small Angle Electron Scattering (RSAES) can meet certain dimensional metrology requirements of the semiconductor industry.

Reflective Small Angle Electron Scattering to Characterize Nanostructures on Opaque Substrates.

Features sizes in integrated circuits (ICs) are often at the scale of 10 nm and are ever shrinking. ICs appearing in today's computers and hand held devices are perhaps the most prominent examples. These smaller feature sizes demand equivalent advances in fast and accurate dimensional metrology for both development and manufacturing.

Strain measurement of 3D structured nanodevices by EBSD.

We present a new methodology to accurately measure strain magnitudes from 3D nanodevices using Electron Backscatter Diffraction (EBSD). Because the dimensions of features on these devices are smaller than the interaction volume for backscattered electrons, EBSD patterns from 3D nanodevices will frequently be the superposition of patterns from multiple material regions simultaneously. The effect of this superposition on EBSD strain measurement is demonstrated, along with an approach to separate EBSD patterns from these devices via subtraction.

Stochastic behavior of nanoscale dielectric wall buckling.

The random buckling patterns of nanoscale dielectric walls are analyzed using a nonlinear multi-scale stochastic method that combines experimental measurements with simulations. The dielectric walls, approximately 200 nm tall and 20 nm wide, consist of compliant, low dielectric constant (low-) fins capped with stiff, compressively stressed TiN lines that provide the driving force for buckling. The deflections of the buckled lines exhibit sinusoidal pseudoperiodicity with amplitude fluctuation and phase decorrelation arising from stochastic variations in wall geometry, properties, and stress state at length scales shorter than the characteristic deflection wavelength of about 1000 nm.

Near-theoretical fracture strengths in native and oxidized silicon nanowires.

In this letter, fracture strengths σ f of native and oxidized silicon nanowires (SiNWs) were determined via atomic force microscopy bending experiments and nonlinear finite element analysis. In the native SiNWs, σ f in the Si was comparable to the theoretical strength of Si〈111〉, ≈22 GPa. In the oxidized SiNWs, σ f in the SiO2 was comparable to the theoretical strength of SiO2, ≈6 to 12 GPa.

Assessing strain mapping by electron backscatter diffraction and confocal Raman microscopy using wedge-indented Si.

The accuracy of electron backscatter diffraction (EBSD) and confocal Raman microscopy (CRM) for small-scale strain mapping are assessed using the multi-axial strain field surrounding a wedge indentation in Si as a test vehicle. The strain field is modeled using finite element analysis (FEA) that is adapted to the near-indentation surface profile measured by atomic force microscopy (AFM). The assessment consists of (1) direct experimental comparisons of strain and deformation and (2) comparisons in which the modeled strain field is used as an intermediate step.

Combining nanocalorimetry and dynamic transmission electron microscopy for in situ characterization of materials processes under rapid heating and cooling.

Nanocalorimetry is a chip-based thermal analysis technique capable of analyzing endothermic and exothermic reactions at very high heating and cooling rates. Here, we couple a nanocalorimeter with an extremely fast in situ microstructural characterization tool to identify the physical origin of rapid enthalpic signals. More specifically, we describe the development of a system to enable in situ nanocalorimetry experiments in the dynamic transmission electron microscope (DTEM), a time-resolved TEM capable of generating images and electron diffraction patterns with exposure times of 30 ns-500 ns.

Prototype cantilevers for quantitative lateral force microscopy.

Prototype cantilevers are presented that enable quantitative surface force measurements using contact-mode atomic force microscopy (AFM). The "hammerhead" cantilevers facilitate precise optical lever system calibrations for cantilever flexure and torsion, enabling quantifiable adhesion measurements and friction measurements by lateral force microscopy (LFM). Critically, a single hammerhead cantilever of known flexural stiffness and probe length dimension can be used to perform both a system calibration as well as surface force measurements in situ, which greatly increases force measurement precision and accuracy.