In this report, atomic force microscopy (AFM) nanolithography and electrochemical anodic oxidation using bias-assisted lithography are used to created oxide patterns on the surface of a silicon substrate. Non-contact mode imaging was conducted after the lithography process to confirm the successful fabrication of oxide patterns on the surface as well as to distinguish the surface difference between the oxide layers and silicon substrate. With only a few seconds of run time, oxide patterns as narrow as 35 nm in width were created illustrating that the bias mode in the Park Scientific SmartLitho software can be used to generate well-defined nanoscale patterns and features.

Faraday rotators in optical isolators, typically composed of iron garnets, are photonic analogues of electrical diodes in that they do not allow reciprocal transmission of light. Isolators are especially important for blocking back-reflected light from reaching source lasers, as such feedback gives rise to unwanted noise and instabilities. In commonly implemented photonic integrated circuits (PICs), isolation is the only critical function that cannot yet be achieved by direct integration. While several techniques have been explored for integrating high-gyrotropy garnets into silicon-on-insulator PICs, this article focuses on sputter deposition, which is the most up-scalable process. High-gyrotropy Ce-doped yttrium iron garnet on nongarnet substrates can be made by sputter deposition with the use of garnet seed layers. Because these seed layers can compromise device performance, seed layer-free terbium iron garnet (TIG) has also recently been developed. Careful doping of TIG can produce Faraday rotations with opposite chiralities, which enable new device designs. Most optical isolator designs involve two-dimensional transverse magnetic-mode structures, such as interferometers or ring resonators, which employ nonreciprocal phase shift. One-dimensional Faraday rotation waveguides with quasi-phase matching have been shown to enable direct integration of isolators for all modes, including the transverse electric mode of lasers currently available for fully integrated PICs.

Digital image correlation (DIC) in a scanning electron microscope and high-angular resolution electron backscatter diffraction (HREBSD) provide valuable and complementary data concerning local deformation at the microscale. However, standard surface preparation techniques are mutually exclusive, which makes combining these techniques in situ impossible. This paper introduces a new method of applying surface patterning for DIC, namely a urethane microstamp, that provides a pattern with enough contrast for DIC at low accelerating voltages, but is virtually transparent at the higher voltages necessary for HREBSD and conventional EBSD analysis. Furthermore, microstamping is inexpensive and repeatable, and is more suitable to the analysis of patterns from complex surface geometries and larger surface areas than other patterning techniques.

Surface textures with three-dimensional (3D) architectures demonstrate the ability to control interfacial, optical, chemical, and mechanical properties. Potential applications range from device-scale biomolecule sensing to meter-scale optical or nonwetting coatings. In recent years, capillary forming has become a versatile and scalable approach to creating complex geometries at the nano- and micron scales. Surface tension of a liquid can deform straight pillars and assemble them into 3D architectures with predetermined orientation, where short-range adhesion forces stabilize the final forms. A variety of techniques have been demonstrated for carbon nanotubes and polymer filamentary materials to fabricate useful devices and textures. We discuss these materials and processes as well as the underlying elasto-capillary physics. We indicate the need for new simulation tools to design and engineer elasto-capillary transformations and methods to increase their throughput toward scalable manufacturing.

Block copolymers (BCPs) microphase-separate to form periodic patterns with periods of a few nanometers and above without the need for lithographic guidance. These self-assembled nanostructures have a variety of bulk geometries, including alternating lamellae, gyroids, arrays of cylinders or spheres, tiling patterns and core–shell structures, depending on the molecular architecture of the polymer and the volume fraction of its blocks. Non-bulk morphologies can be produced, the ordering of the microdomains can be improved, and their locations can be directed using various templates and processing strategies. The blocks themselves can constitute a functional material, such as a photonic crystal, or they can be used as a mask to pattern other functional materials, functionalized directly by various chemical approaches, or used as a scaffold to assemble nanoparticles or other nanostructures. BCPs offer tremendous flexibility in creating nanostructured materials with a range of applications in microelectronics, photovoltaics, filtration membranes, and other devices.

Conventional photolithography is an effective patterning technique that has enabled modern electronics and advanced micro- and nanoscale devices. However, it has limitations, including high cost, limited resolution, and poor compatibility with unconventional materials that may be soft, nonplanar, or difficult to process. There is active research ongoing to develop unconventional patterning methods such as self-organization and self-folding. Self-organization harnesses various driving forces to produce patterns without external intervention and includes methods such as self-assembly of block copolymers, capillary-driven assembly of micro-/nanoscale structures, and thin-film instabilities. Self-folding (origami)—and its cousin, kirigami—harnesses patterning and materials strategies to convert planar substrates into three-dimensional shapes in response to external stimuli. These multidisciplinary approaches open many engineering opportunities by providing new and versatile material functionalities. This article overviews the field and the topics covered in the articles in this issue of MRS Bulletin, highlighting recent progress in patterning approaches based on self-organization and self-folding.

Focused ion beam microscopes are extremely versatile and powerful instruments for materials research. These microscopes, when coupled in a system with a scanning electron microscope, offer the opportunity for novel sample imaging, sectioning, specimen preparation, three-dimensional (3D) nano- to macroscale tomography, and high resolution rapid prototyping. The ability to characterize and create materials features in a site-specific manner at nanoscale resolution has provided key insights into many materials systems. The advent of novel instrumentation, such as new ion sources that encompass more and more of the periodic table, in situ test harnesses such as cryogenic sample holders for sensitive material analyses, novel detector configurations for 3D structural, chemical, and ion contrast characterization, and robust and versatile process automation capabilities, is an exciting development for many fields of materials research.

Pulsed laser induced plasma in water produces multiple bubbles with the passage of laser pulse. Shadowgraphy and beam deflection set-up is used to study the temporal and spatial evolution of these bubbles as a function of distance from the laser focus. The formation of multiple bubbles, bubble coalescence, and their effect onto cavity dynamics is reported. Bubble radius and the corresponding velocities from shadowgraphy is used to calculate the maximum gas pressure inside the bubble using Neppiras model. The maximum pressure inside the cavity is found to be 0.4 MPa at the laser focus.

Carbon nanotubes are interesting for studying the remarkable electronic properties of one-dimensional (1D) quantum systems. Electron flow in such systems is not described by Fermi liquid theory—restricted dimensionality leads to the appearance of collective excitations—or Luttinger liquid behavior. Previous studies have probed Luttinger liquid behavior by tunneling into or between one-dimensional systems. We propose to extend these studies by using narrow top gates to introduce tunable tunnel barriers within nanotubes. We report on the scalable fabrication of carbon nanotube-based transistors with nanowire top gates. We have used electron-beam lithography (EBL) to create single-walled carbon nanotube (SWNT) transistors with source-drain spacings down to 200 nm and with sub-30 nm metal top gates for creating tunable tunnel barriers. The top metal gate is isolated from the nanotube by a thin aluminum oxide layer deposited by atomic layer deposition. We fabricated chips with 100 devices using multiple electron-beam lithography alignment steps and achieved overall placement better than 30 nm. The details of top-gated SWNT transistor fabrication are presented, and initial transport measurements on fabricated devices are discussed.

As revolutionary as microelectronics has been as a technology, there are functions that it does not address. Microelectronics focuses on ever-smaller integrated circuits (ICs) in ever-fewer square millimeters of space to increase clock speeds and decrease the power required for computer processing functions. However, applications requiring control, communications, computing, and sensing over a large area are difficult or costprohibitive to achieve because of the material incompatibilities of traditional ICs with structures, materials, and manufacturing technology. Macroelectronics addresses these applications with the aim of providing active control circuitry in situ over areas of many square meters for displays, solar panels, x-ray imagers, surface measurements, structural shape control, vehicle health monitoring, and other large-system applications. The materials challenges of macroelectronics integrated circuits (MEICs) reviewed in this issue include lightweight flexible substrates, thin-film transistors (TFTs) with IC or near-IC performance, modeling, and manufacturing technology. Compatible component materials, flexible substrates, processing conditions, host system composition, and functionality provide grand challenges that are just beginning to be addressed by researchers.

This article reports conversion chemistry of preceramic polymer to ceramic phase during the fabrication of high-temperature stable silicon carbide and silicon carbonitride monolithic porous microchannels. The micromolding in capillariesmethod is used to fabricate porous channels by the initial infiltration of a solution of 1.5-μm diameter silica spheres or 1-μm diameter polystyrene spheres into polydimethylsiloxane channels followed by filling the void space among the spheres by using viscous commercial polymeric precursors. Subsequently, the polymer-sphere composite channel was cured and pyrolysed at 1200 °C under inert atmosphere, and final wet etching step of silica spheres with 10% hydrofluoric acid solution developed the pore structures by removing the silica spheres, whereas polystyrene sphere decomposes at the early stage of pyrolysis.

Nanoimprint lithography is a potentially low-cost, high-resolution patterning technique, but most of the surrounding development work has been directed toward tool designs and processing techniques. There remains a tremendous opportunity and need to develop new materials for specific nanoimprint applications. This article provides an overview of relevant materials-related development work for nanoimprint lithographic applications. Material requirements for nanoimprint patterning for the sub-45-nm integrated-circuit regime are discussed, along with proposed nanoimprint applications such as imprintable dielectrics, conducting polymers, biocompatible materials, and materials for microfluidic devices. Polymers available for thermal nanoimprint processing and photocurable precursors for ultraviolet-assisted nanoimprint lithography are discussed.

For the last four decades, the feature sizes of electronic devices for computers have been reduced by a factor of two roughly every 18 months. The result has been a tremendous increase in computational power and reduction in the cost of computing, as measured by cost per function, of nearly 30% annually, so that computations can be done for a billionth of the cost of using the technology of the 1950s. However, devices will soon be so small that the current technology used to produce them will have reached its limits, and the graininess of individual atoms will affect their behavior. This issue focuses on techniques to make tiny devices with dimensions under 45 nm (45 billionths of a meter) for the next generation of devices.Techniques start with coupling currently used 193-nm and 157-nm optical lithography with liquid immersion to reduce the effective wavelength. Other techniques include microprinting, self-assembly, templating, and using supercritical fluids to avoid the effects of surface tension while enabling solution-based processing at such small dimensions. The development of three-dimensional structures that are approaching this scale is also discussed.The methods presented will have an effect on many areas of technology, including, in addition to electronics, advanced sensor technology, energy conversion, catalysis, and nanoelectromechanical systems.

As the size scale of device features becomes ever smaller, conventional lithographic processes become increasingly more difficult and expensive, especially at a minimum feature size of less than 45 nm. Consequently, to achieve higher-density circuits, storage devices, or displays, it is evident that alternative routes need to be developed to circumvent both cost and manufacturing issues.

An ideal process would be compatible with existing technological processes and manufacturing techniques; these strategies, together with novel materials, could allow significant advances to be made in meeting both short-term and long-term demands for higher-density, faster devices. The self-assembly of block copolymers (BCPs), two polymer chains covalently linked together at one end, provides a robust solution to these challenges. As thin films, immiscible BCPs self-assemble into a range of highly ordered morphologies where the size scale of the features is only limited by the size of the polymer chains and are, therefore, nanoscopic.

While self-assembly alone is sufficient for a number of applications in fabricating advanced microelectronics, directed, self-orienting, self-assembly processes are also required to produce complex devices with the required density and addressability of elements to meet future demands. Both strategies require the design and synthesis of polymers that have well-defined characteristics such that the necessary fine control over the morphology, interfacial properties, and simplicity of processes can be realized. By combining tailored self-assembly processes (a “bottom-up” approach) with microfabrication processes (a “top-down” approach), the ever-present thirst of the consumer for faster, better, and cheaper devices can be met in very simple, yet robust, ways. The integration of novel chemistries with the manipulation of self-assembly will be treated in this article.

The world of nanomaterials has become the real world for most applications in the area of nanotechnology. As postsynthesis handling of materials at the nanoscale level is impractical, nanomaterials must be synthesized directly as part of a device or circuit. The demands of nanotechnology have led to modifications in the design of transmission electron microscopes (TEMs) that enable in situ synthesis and characterization simultaneously. The environmental TEM (ETEM) is one such modified instrument that has often been used to follow gas–solid and/or liquid–solid interactions at elevated temperatures. Although the history and development of the ETEM, also called the controlled atmosphere or environmental cell TEM, is as old as transmission electron microscopy itself, developments in the design of medium-voltage TEMs have succeeded in bringing resolutions down to the subnanometer level. A modern ETEM equipped with a field-emission gun, energy filter or electron energy-loss spectrometer, scanning transmission electron microscopy coils, and bright-field and dark-field detectors can be a versatile tool for understanding chemical processes at the nanometer level. This article reviews the design and operations of a dedicated ETEM. Its applications range from the in situ characterization of reaction steps, such as oxidation-reduction and hydroxylation, to the in situ synthesis of nanomaterials, such as quantum dots and carbon nanotubes. Some examples of the current and the future applications for the synthesis and characterization of nanomaterials are also discussed.