A common characteristic in semiconductor nanostructures is the lattice strain originating from the lattice mismatch between layers of different compositions. Three-dimensional strain measurement in crystals using transmission electron microscopy (TEM) techniques has been the subject of intense works for decades. This information is required for the strain-bandgap engineering being used by our current fast computers and necessary for future quantum computers. However, the missing information was the 3rd dimension that is the atomic displacement and how it changes along the electron-beam direction. The strain information along the electron-beam direction is in the phase of the diffracted beam, which has been obtained recently by the novel technique of self-interference of split higher order Laue zone line (SIS-HOLZ). SIS-HOLZ has been made possible by the correction of the beam aberrations having its analytical and experimental details reported here for the atomic displacement profile existing at the interface of a Si and Si/Si0.8Ge0.2 superlattice.

Access to cutting-edge technologies in materials science and engineering within K-12 education is a great struggle in developing countries. In this work, a problem-based, hands on set of seven modules for integrating Holographically-formed Polymer Dispersed Liquid Crystal (H-PDLC) Bragg Grating thin films into the Kenyan secondary physics, chemistry and mathematics curriculum is proposed. Through funding provided by the National Science Foundation, a pilot study of the integration of these modules, using the National Academy of Engineering’s (NAE) Grand Challenges for Engineering as a contextual vessel, is carried out. The efficacy of these curriculum-integrated modules in communicating real world materials science and engineering challenges is examined using qualitative and quantitative means. A method for expanding the use of this experience with other graduate students is proposed.

A confocal scanning laser holography (CSLH) microscope that uniquely combines the concepts of confocal microscopy with holography has been validated for making nonintrusive, full three-dimensional (3D) intensity and phase measurements of objects from a single viewpoint of observation without loss of object information. The phase measurements have been used to determine the 3D refractive indices of a point source heated silicone oil. The refractive indices are converted to 3D temperature measurements, which are useful for heat transfer studies. An important feature of CSLH is its nonintrusive 3D scanning method, which enables its application to the study of Marangoni convection in microgravity with minimal operational vibrations affecting the motion of fluid in the specimen.

Three techniques based on transmission electron microscope (TEM) have been successfully applied to measure strain/stress in the channel area of PMOS semiconductor devices with embedded SiGe in the source/drain areas: convergent beam electron diffraction (CBED), nano beam diffraction (NBD) and dark-filed holography (DFH). Consistent channel strain measurements from the three techniques on the same TEM sample (eSiGe PMOS with 17%Ge) were obtained. Reliable strain/stress measurement results in the channel area have been achieved with very good agreement with computer-aided design (TCAD) calculations.

We report the heterogeneous integration of a multifunctional sensor based on polymer porous photonic bandgap (P3BG) structure and xerogel based luminescence sensor technology. The P3BG structure was fabricated using holographic interferometry. Initially, holographic interferometry of a photo-activated prepolymer syrup that included a volatile solvent as well as monomer, photoinitiator, and co-initiator was used to initiate photopolymerization. Subsequent UV curing resulted in well defined lamellae of the polymer separated by porous polymer regions that created a high quality photonic bandgap structure. The resulting P3BG structure was then integrated with the xerogel based luminescence element to produce a luminescence sensor with a selective narrow band reflector. The prototype xerogel based luminescence sensor element consisted of an O2 sensing material based on spin coated tetraethylorthosilane (TEOS) composite xerogel films containing tris (4,7-diphenyl-1,10-phenanthroline) ruthenium (II) ([Ru(dpp)3]2+) luminophore. We demonstrated enhancement of the signal-to-noise ratio (SNR) of this integrated multifunctional sensor while maintaining the same sensitivity to O2 sensing of the xerogel based element. The resulting advantages and enhanced SNR of this integrated sensor will provide a template for other luminescence based assays to support highly sensitive and cost-effective sensor systems for biomedical applications.

A simple and efficient approach for fabricating silicon nanopillar arrays with a high aspect ratio and controllable sidewall profiles has been developed by using holographic lithography and a novel single-step deep reactive ion etching. During the etching process, scalloping of the sidewalls can be avoided while reserving the high mask selectivity and high etching rate. Besides, the sidewall angle of resultant patterns can be adjusted by tuning the composition of the gas mixture of single-step DRIE process. We further fabricate a tapered silicon nanopillar array and observe its photonic bandgap property. We believe that the good optical performance of this tapered silicon nanopillar array realized by the proposed approach shows the promising of this process for various applications.

Theoretical analysis can impart great benefits on the rationale design of 3D photonic structures by revealing the underlying mechanisms of structural distortion during each processing step. In this report, we quantitatively study the distortion of a three-term diamond-like structure fabricated in SU-8 polymer by four-beam interference lithography, which can be attributed to refraction at the air-film interface, and resist film shrinkage during lithographic process. In study of photonic bandgap (PBG) properties of Si photonic crystals templated by the SU-8 structures, we find that the distortion has degraded the quality of PBGs. Furthermore, we theoretically design new optical setups to fabricate three-term diamond-like structure with minimal deformation. Instead of single exposure of four beams, we use triple exposure of two beams, one from the central beam and the other from the side beam each time. A set of new linear polarization vectors is suggested to enhance the contrast between the minimal and maximal intensities of interference pattern.

We report a new technique of creating a nanoporous polymeric nanostructure by photo-patterning emulsions generated from a formamide (polar phase) and an acrylate-monomer (nonpolar phase). Formamide is a highly polar solvent that forms well dispersed, non-aqueous emulsion droplets within the monomer-containing nonpolar phase before holographic patterning. Photochemically initiated polymerization of the nonpolar phase (acrylate monomer) forces the formation of ordered formamide emulsions defined by the holographic interference. Evaporation of the formamide from the ordered structure yields a periodic structure with high optical reflectivity and a wide reflection bandwidth. The average size and the size distribution of formamide droplets in the photopolymer fluid must be controlled to fabricate a periodic structure with high reflectivity. Furthermore, we found that the addition of sodium dioctyl sulfosuccinate (AOT) surfactant helps to stabilize the formamide emulsion which further facilitates the formation of the ordered nanopores with uniform size.

Nanosize particles are of fundamental and practical interest for developing advanced materials and devices and micro and nanostructures. As feature sizes shrink, nanoparticle contamination is also becoming increasingly important to achieve and maintain high product yields. In order to employ appropriate material and product development strategies, or institute preventive assembly and remediation strategies to control nanoparticle contamination, it is essential to understand the nature of nanoparticles and to characterize these particles. Particles in the size range 0.1 nm to 100 nm present unique challenges and opportunities for their imaging and characterization. Critical information for this purpose is the number and size of the particles, their morphology, and their physical and chemical structure. Because of this importance, many advances and new developments have been made in qualitative and quantitative characterization techniques for particles in this size range, including neutron holography, three dimensional atom probe imaging, ultrafast microscopy and crystallography, magnetic resonance force microscopy, and high-resolution x-ray crystallography of non-crystalline structures. It is now possible to completely characterize nanoparticles from 0.1 nm to 100 nm size. A brief review of the nature of nanoparticles is presented and recent developments in selected characterization techniques are described.

We have recently shown the successful synthesis of zirconia nanoparticles that can be optimized for use in volume phase holography by a post-functionalization surface treatment. Here, we present further investigations on the surface modification treatment with the aim of providing tools to tailor the nanoparticle compatibility to the photocurable organic matrix. Highly crystalline ZrO2 nanoparticles with a mean diameter of 5nm are synthesized in multigram yield through a one-pot solvothermal reaction of zirconium (IV) n-propoxide in benzyl alcohol. It is shown that the yield of the ZrO2 nanoparticles and stability of the nanoparticle dispersions are strongly dependent on the synthesis temperature. Post-synthetic surface modification of ZrO2 nanoparticles using several aliphatic ligands with different surface binding groups such as carboxylate (-COO−), amine (−NH2), phosphate (−PO4) and methoxysilane (−SiOCH3) was performed in order to compare the binding ability of these functional groups to the nanoparticle surface and therefore provide a new rational approach for nanoparticle stabilization with organic ligands.

We report the development of oxygen sensors using polymer photonic bandgap structure and CMOS chips. These integrated sensors provide a new platform for the development of low cost, low (battery) powered, light weight, robust, fast and small sensors. We demonstrate an approach to encapsulation of chemical and biological recognition elements within the porous structures. This sensing platform is built on our recently demonstrated nanofabrication technique using holographic interferometry of a photo-activated mixture that includes a volatile solvent as well as monomers, photoinitiators, and co-initiators. Resulting structure is nanoporous polymer 1D photonic bandgap structures that has reflection grating property and can be directly integrated into optical sensor systems that we have previously developed. For optical sensor system, CMOS (Complementary Metal Oxide Semiconductor) detectors that include phototransistors, trans impedance amplifier, and other signal processing units are used. Combining CMOS chip and nano-porous polymer reflection grating, we demonstrate an oxygen sensor as a prototype by encapsulating the fluorophore (tris(4,7-diphenyl-1,10-phenathroline)ruthenium(II) using fluorescence intensity.

Massively Parallel Scanning Probe Microscopy is an obvious path for enhancing the acquisition speed and the imaging range of current based-AFM metrology devices. Current experimental systems, based on active probes array, would reach their limits in density and hardware complexity. This paper presents a new approach with the promise to break several of these barriers. The key idea is readout of a Scanning Probes Microscope (SPM) array by an interferometer technique called digital holography which directly gives the cantilever phase information at each pixel of a CCD array. This means that no contact line to each individual SPM probes is needed, allowing us to reach very high density of probes. The phase information is available in a parallel form in real-time. Moreover, the digital holography optical setup (Digital Holography Microscope or DHM) needs in principle no expensive components, optical (or, to a large extent, mechanical) imperfections being compensated in the signal processing, i.e. in electronics. This gives the system the potential for a low cost device with fast and large readout capability.

Closely-spaced ferromagnetic nanoparticles are of interest for applications that include data storage, magnetic imaging and drug delivery. Here, we use off-axis electron holography and micromagnetic simulations to study the magnetic properties of iron nanoparticles encapsulated in three-dimensional arrays of carbon nanotubes. The nanotubes constrain the shapes, sizes and separations of the nanoparticles, as well protecting them from oxidation. We record magnetic induction maps from individual particles that each contain a single magnetic domain. We also discuss the use of electron holography to assess magnetostatic interactions between adjacent particles.

During in situ transmission electron microscopy (TEM) field emission experiments, carbon nanotubes are observed to strongly diffract the imaging TEM electron beam. We demonstrate that this effect is identical to that of a standard electrostatic biprism. We also demonstrate that the nanotube biprism can be used to capture electron-holographic information.