The widely used 'silicon-on-insulator' (SOI) system consists of a layer of single-crystalline silicon supported on a silicon dioxide substrate. When this silicon layer (the template layer) is very thin, the assumption that an effectively infinite number of atoms contributes to its physical properties no longer applies, and new electronic, mechanical and thermodynamic phenomena arise, distinct from those of bulk silicon. The development of unusual electronic properties with decreasing layer thickness is particularly important for silicon microelectronic devices, in which (001)-oriented SOI is often used. Here we show--using scanning tunnelling microscopy, electronic transport measurements, and theory--that electronic conduction in thin SOI(001) is determined not by bulk dopants but by the interaction of surface or interface electronic energy levels with the 'bulk' band structure of the thin silicon template layer. This interaction enables high-mobility carrier conduction in nanometre-scale SOI; conduction in even the thinnest membranes or layers of Si(001) is therefore possible, independent of any considerations of bulk doping, provided that the proper surface or interface states are available to enable the thermal excitation of 'bulk' carriers in the silicon layer.

Low cost, direct writing of conductive traces is highly desired for applications in nanoelectronics, photonics, circuit repair, flexible electronics, and nanoparticle-based gas detection. The unique ability of Dip Pen Nanolithography ͑DPN ® ͒ to direct write a variety of materials onto suitable surfaces with nanoscale resolution and area-specific patterning is leveraged in this work. We present a direct-write approach toward creating traces with commercially available silver nanoparticle ͑AgNP͒-based inks using DPN. In this work we demonstrate submicron AgNP feature creation together with a discussion on the ink transport mechanism.

Quantitative electric force microscopy ͑EFM͒ is usually restricted to flat samples, because vertical sample topography traditionally makes quantitative interpretation of EFM data difficult. Many important samples, including self-assembled nanostructures, possess interesting nanoscale electrical properties in addition to complex topography. Here we present techniques for analysis of EFM images of such samples, using voltage modulated EFM augmented by three-dimensional simulations. We demonstrate the effectiveness of these techniques in analyzing EFM images of self-assembled SiGe nanostructures on insulator, report measured dielectric properties, and discuss the limitations sample topography places on quantitative measurement.

Single-crystal iron boride (Fe3B) nanowires were synthesized on Pt and Pd (Pt/Pd) coated sapphire substrates by a chemical vapor deposition method at 800 °C using boron triiodide (BI3) and iron iodide (FeI2) as precursors. Morphology of the Fe3B nanowires can be controlled by manipulating the Pt/Pd film thickness and the growth time. Transmission electron microscopy and selected area electron diffraction were used to analyze the crystal structures of these novel materials. Electron energy-loss spectroscopy and X-ray energy-dispersive spectroscopy studies on these nanowires confirm that they are composed of boron and iron. Scanning electron microscopy was employed to observe the morphology of these nanomaterials. The typical size of the iron boride nanowires is about 5−50 nm in width and 2−30 μm in length. The vapor−liquid−solid (VLS) growth process is shown to be the growth mechanism of the Fe3B nanowires. Room temperature magnetic force microscopy investigations on the iron boride nanowires suggest that they are ferromagnetic nanowires with a single-domain configuration.

A variation of electric force microscopy ͑EFM͒ is used to measure the electrical isolation of SiGe quantum dots ͑QDs͒. The SiGe QDs are grown on mesas of ultrathin silicon on insulator. Near the mesa edges, the thin silicon layer has been incorporated into the QDs, resulting in electrically isolated QDs. Away from the edges, the silicon layer is not incorporated and has a two-dimensional resistivity of less than 800 T⍀ per sq, resulting in relatively short RC times for charge flow on the mesa. The EFM technique we use here is a powerful probe of samples and devices with floating-gate geometries.

is an assistant professor of instruction with the Undergraduate Engineering Office and the Mechanical Engineering department at Northwestern University. His research explored novel ways to control robotic prosthetic hands. He is very passionate about student education and has taught multiple courses at the undergraduate level that include manufacturing, freshman and capstone design, experimental methods, and thermodynamics. He greatly enjoys advising all levels of undergraduate and early graduate students. He has been highly involved with the Lightboard studio and exploring models for effective online and hybrid teaching methods.

is an assistant professor of instruction with the Undergraduate Engineering Office and the Mechanical Engineering department at Northwestern University. His research was conducted at the intersection of robotics and biomechanics in the field of human-machine interactions, and explored novel ways to control robotic prosthetic hands. He is very passionate about student education and currently teaches five separate courses at the undergraduate level that include manufacturing, design, experimental methods, and thermodynamics. He greatly enjoys advising all levels of undergraduate and early graduate students. He is the producer for the Lightboard studio, and is currently exploring models for effective online and hybrid teaching models.

Precision nanoscale deposition is a fundamental requirement for much of current nanoscience research. Further, depositing a wide range of materials as nanoscale features onto diverse surfaces is a challenging requirement for nanoscale processing systems. As a high resolution scanning probe-based direct-write technology, Dip Pen Nanolithography ® (DPN ® ) satisfies and exceeds these fundamental requirements. Herein we specifically describe the massive scalability of DPN with two dimensional probe arrays (the 2D nano PrintArray™). In collaboration with researchers at Northwestern University, we have demonstrated massively parallel nanoscale deposition with this 2D array of 55,000 pens on a centimeter square probe chip. (To date, this is the highest cantilever density ever reported.) This enables direct-writing flexible patterns with a variety of molecules, simultaneously generating 55,000 duplicates at the resolution of single-pen DPN. To date, there is no other way to accomplish this kind of patterning at this unprecedented resolution. These advances in high-throughput, flexible nanopatterning point to several compelling applications. The 2D nano PrintArray can cover a square centimeter with nanoscale features and pattern 10 7 µm 2 per hour. These features can be solid state nanostructures, metals, or using established templating techniques, these advances enable screening for biological interactions at the level of a few molecules, or even single molecules; this in turn can enable engineering the cell-substrate interface at sub-cellular resolution.