Electrochemical Deposition Method Utilizing Microdroplets of Solution

A method of electrochemical deposition uses microdroplets of electrolytic solution over a targeted small circuit element. Only the targeted circuit element is electrically biased so that deposition occurs on the surface of that element, underneath the microdroplet, and nowhere else unless it is under other microdroplet(s). The invented method achieves extremely accurate and selective electrochemical deposition with a tiny amount of electrolytic solution, compared to conventional submersive and/or immersive methods, and eliminates the need for masking or etching, reducing the costs of manufacture and amount of waste electrolytic solution produced

Cavity Resonant Mode in a Metal Film Perforated with Two-Dimensional Triangular Lattice Hole Arrays

The transmission property of metallic films with two-dimensional hole arrays is studied experimentally and numerically. For a triangular lattice subwavelength hole array in a 150 nm thick Ag film, both cavity resonance and planar surface modes are identified as the sources of enhanced optical transmissions. Semi-analytical models are developed for calculating the dispersion relation of the cavity resonant mode. They agree well with the experimental results and full-wave numerical calculations. Strong interaction between the cavity resonant mode and surface modes is also observed

On the Thermal Activation of Negative Bias Temperature Instability

The temperature dependence of negative bias temperature instability (NBTI) is investigated on 2.0nm SiO2 devices from temperatures ranging from 300K down to 6K with a measurement window of ~12ms to 100s. Results indicate that classic NBTI degradation is observed down to ~200K and rarely observed at temperatures below 140K in the experimental window. Since experimental results show the charge trapping component contributing to NBTI is thermally activated, the results cannot be explained with the conventionally employed elastic tunneling theory. A new mechanism is observed at temperatures below 200K where device performance during stress conditions improves rather than degrades with time, which is opposite to the classical NBTI phenomenon

Enhanced DNA Sensing via Catalytic Aggregation of Gold Nanoparticles

A catalytic colorimetric detection scheme that incorporates a DNA-based hybridization chain reaction into gold nanoparticles was designed and tested. While direct aggregation forms an inter-particle linkagefrom only one target DNA strand, catalytic aggregation forms multiple linkages from a single target DNA strand. Gold nanoparticles were functionalized with thiol-modified DNA strands capable of undergoing hybridization chain reactions. The changes in their absorption spectra were measured at different times and target concentrations and compared against direct aggregation. Catalytic aggregation showed a multifold increase in sensitivity at low target concentrations when compared to direct aggregation. Gelelectrophoresis was performed to compare DNA hybridization reactions in catalytic and direct aggregation schemes, and the product formation was confirmed in the catalytic aggregation scheme at low levels of target concentrations. The catalytic aggregation scheme also showed high target specificity. This application of a DNA reaction network to gold nanoparticle-based colorimetric detection enables highly-sensitive, field-deployable, colorimetric readout systems capable of detecting a variety of biomolecules

Atomic Force Microscopy of DNA Self-Assembled Nanostructures for Device Applications

DNA nanotechnology, which relies on Watson-Crick hybridization, is a versatile selfassembly process whereby a variety of complex nanostructures can be fabricated with sublithographic features.[1] Adopting this technology, 1012 identical devices can be synthesized to have hundreds of components with 1nm resolution. Example nanostructures include: 1) DNA motifs [2], 2) two-dimensional DNA crystals [3], and DNA origami [4]. Currently, this technology is being adopted towards electronic, optical, and opto-electronic devices.[5

Integrating Through-Wafer Interconnects with Active Devices and Circuits

Through wafer interconnects (TWIs) enable vertical stacking of integrated circuit chips in a single package. A complete process to fabricate TWIs has been developed and demonstrated using blank test wafers. The next step in integrating this technology into 3D microelectronic packaging is the demonstration of TWIs on wafers with preexisting microcircuitry. The circuitry must be electrically accessible from the backside of the wafer utilizing the TWIs; the electrical performance of the circuitry must be unchanged as a result of the TWI processing; and the processing must be as cost effective as possible. With these three goals in mind, several options for creating TWIs were considered. This paper explores the various processing options and describes in detail, the final process flow that was selected for testing, the accompanying masks that were designed, the actual processing of the wafers, and the electrical test results

Molecular Dynamics Simulations of Cyanine Dimers Attached to DNA Holliday Junctions

Dye aggregates and their excitonic properties are of interest for their applications to organic photovoltaics, non-linear optics, and quantum information systems. DNA scaffolding has been shown to be effective at promoting the aggregation of dyes in a controllable manner. Specifically, isolated DNA Holliday junctions have been used to achieve strongly coupled cyanine dye dimers. However, the structural properties of the dimers and the DNA, as well as the role of Holliday junction isomerization are not fully understood. To study the dynamics of cyanine dimers in DNA, molecular dynamics simulations were carried out for adjacent and transverse dimers attached to Holliday junctions in two different isomers. It was found that dyes attached to adjacent strands in the junction exhibit stronger dye-DNA interactions and larger inter-dye separations compared to transversely attached dimers, as well as end-to-end arrangements. Transverse dimers exhibit lower inter-dye separations and more stacked configurations. Furthermore, differences in Holliday junction isomer are analyzed and compared to dye orientations. For transverse dyes exhibiting the smaller inter-dye separations, excitonic couplings were calculated and shown to be in agreement with experiment. Our results suggested that dye attachment locations on DNA Holliday junctions affect dye-DNA interactions, dye dynamics, and resultant dye orientations which can guide the design of DNA-templated cyanine dimers with desired properties

Limitations of Poole–Frenkel Conduction in Bilayer HfO\u3csub\u3e2\u3c/sub\u3e/SiO\u3csub\u3e2\u3c/sub\u3e MOS Devices

The gate leakage current of metal–oxide– semiconductors (MOSs) composed of hafnium oxide (HfO2) exhibits temperature dependence, which is usually attributed to the standard Poole–Frenkel (P–F) transport model. However, the reported magnitudes of the trap barrier height vary significantly. This paper explores the fundamental challenges associated with applying the P–F model to describe transport in HfO2/SiO2 bilayers in n/p MOS field-effect transistors composed of 3- and 5-nm HfO2 on 1.1-nm SiO2 dielectric stacks. The extracted P–F trap barrier height is shown to be dependent on several variables including the following: the temperature range, method of calculating the electric field, electric-field range considered, and HfO2 thickness. P–F conduction provides a consistent description of the gate leakage current only within a limited range of the current values while failing to explain the temperature dependence of the 3-nm HfO2 stacks for gate voltages of less than 1 V, leaving other possible temperature-dependent mechanisms to be explored

Exciton Delocalization in a DNA-Templated Organic Semiconductor Dimer Assembly

A chiral dimer of an organic semiconductor was assembled from octaniline (octamer of polyaniline) conjugated to DNA. Facile reconfiguration between the monomer and dimer of octaniline–DNA was achieved. The geometry of the dimer and the exciton coupling between octaniline molecules in the assembly was studied both experimentally and theoretically. The octaniline dimer was readily switched between different electronic states by protonic doping and exhibited a Davydov splitting comparable to those previously reported for DNA–dye systems employing dyes with strong transition dipoles. This approach provides a possible platform for studying the fundamental properties of organic semiconductors with DNA-templated assemblies, which serve as candidates for artificial light-harvesting systems and excitonic devices

Multiscaffold DNA Origami Nanoparticle Waveguides

DNA origami templated self-assembly has shown its potential in creating rationally designed nanophotonic devices in a parallel and repeatable manner. In this investigation, we employ a multiscaffold DNA origami approach to fabricate linear waveguides of 10 nm diameter gold nanoparticles. This approach provides independent control over nanoparticle separation and spatial arrangement. The waveguides were characterized using atomic force microscopy and far-field polarization spectroscopy. This work provides a path toward large-scale plasmonic circuitry