Nanoscale Applications for Information and Energy Systems

Strong light confinement on the scale comparable to that of electronics components is desirable for future optical interconnects in high-performance computing systems. It would also open up new possibilities for integrated sensors with much enhanced sensitivity and selectivity. The refraction index contrast provided by group IV and III–V materials becomes insufficient for that, and one has to use metals providing much larger contrast. The dynamics of free carriers in metals is plasma like, resulting in negative dielectric constant below the plasmon frequency, \( \varepsilon (\omega ) < 0 \). This brings us into the area of plasmonics and opens up a possibility to make negative index artificial electromagnetic structures (metamaterials, NIMs) with so-called magnetoplasmon resonances that will mimic the behavior of materials with negative permeability, \( \mu (\omega ) < 0 \), in some frequency range. We will describe various properties of NIMs and then turn over to modern Raman sensors providing single-molecule detection sensitivity. For surface-enhanced Raman probes, the achieved enhancement may reach in excess of 11 orders of magnitude, and we describe the method of pinching gold “nanofingers” to achieve this record enhancement reproducibly.

Nanoplasmonics is a vastly developing area of modern photonics, which is capable of providing mankind with new routes to fast and miniature communication and technologies. With unprecedentedly high bandwidth supplied by photons and subwavelength dimensions supplied by electrons, surface plasmon is the next candidate for the everyday-life information unit. In this chapter we review recent advances in controlling the generation and propagation of surface plasmon polaritons in nanostructured materials as well as utilization of surface plasmons in order to obtain efficient control over optical signals.

Achieving a sustainable energy system providing terawatts (TWs) of electricity is one of the defining challenges of the coming decades. Photovoltaic technology provides the most likely path to realizing TW scale conversion of solar energy in the future and has been on a nearly 40% growth curve over the past two decades. In order to maintain this rapid level of growth, innovations in cell design and conversion efficiency are needed that are compatible with existing technology and can lead to improved performance and lower cost. Nanotechnology offers a number of advantages to realizing such innovation, by providing new materials and the implementation of advanced concepts that circumvent the current physical limits on efficiency. This chapter reviews several of the promising applications of nanotechnology to photovoltaic technologies and their prospects for the future.

The goal of this chapter is to introduce readers to the fundamental and practical aspects of nanotube assemblies made into transparent conducting networks and discuss some practical aspects of their characterization. Transparent conducting coatings (TCC) are an essential part of electro-optical devices, from photovoltaics and light emitting devices to electromagnetic shielding and electrochromic widows. The market for organic materials (including nanomaterials and polymers) based TCCs is expected to show a growth rate of 56.9% to reach nearly $20.3 billion in 2015, while the market for traditional inorganic transparent electronics will experience growth with rates of 6.7% to nearly $103 billion in 2015. Emerging flexible electronic applications have brought additional requirements of flexibility and low cost for TCC. However, the price of indium (the major component in indium tin oxide TCC) continues to increase. On the other hand, the price of nanomaterials has continued to decrease due to development of high volume, quality production processes. Additional benefits come from the low cost, nonvacuum deposition of nanomaterials based TCC, compared to traditional coatings requiring energy intensive vacuum deposition. Among the materials actively researched as alternative TCC are nanoparticles, nanowires, and nanotubes with high aspect ratio as well as their composites. The figure of merit (FOM) can be used to compare TCCs made from dissimilar materials and with different transmittance and conductivity values. In the first part of this manuscript, we will discuss the seven FOM parameters that have been proposed, including one specifically intended for flexible applications. The approach for how to measure TCE electrical properties, including frequency dependence, will also be discussed. We will relate the macroscale electrical characteristics of TCCs to the nanoscale parameters of conducting networks. The fundamental aspects of nanomaterial assemblies in conducting networks will also be addressed. We will review recent literature on TCCs composed of carbon nanotubes of different types in terms of the FOM.

Silicon electroplating offers a low-cost method for the production of high-performance low-cost silicon solar cells that can be used in small portables and large-scale applications, like the grid. Silicon remains the semiconductor of choice because silicon has the best combination of efficiency, cost, durability, and availability. Silicon photovoltaic (PV) devices are likely to dominate the market for a long time. Silicon solar cells have reasonable efficiency (up to 15%), cost (as low as $2/peak watt), and excellent reliability (losing less than 1% power output per year over 25 years), and since silica is abundant, silicon depletion is not a worry. Although silicon is the best photovoltaic option and has the largest market share, it is still too costly to provide the majority of grid power. Cost remains a major barrier to further market penetration, because current thin film semiconducting silicon preparation uses high-temperature (750–1,000°C) deposition processes, such as chemical vapor deposition (CVD), which require high levels of electrical power and energy and convert only 10% of the silane feed to useful silicon. Clearly silicon PV manufacturers need to increase efficiency and lower wastes and cost. Silicon electrodeposition offers an effective alternative to CVD for making silicon devices with substantially reduced processing costs so that solar photovoltaics can be cost competitive with the typical cost for installing new electrical power generators in the grid. Using silicon electrodeposition as the silicon processing in the manufacture of a variety of semiconductor applications is reviewed. A practical way of electroplating silicon from silicon salts dissolved in ionic liquids is discussed with early results and prospects.

Resistive switching in metal oxides is considered one of the most promising storage concept for future generations of nanoscaled nonvolatile memories. In bipolar resistive switching, the resistance of a conductive filament (CF) is controlled through the application of electrical stimuli, and the conductive state of the nanoscaled CF can be used to encode the value of the logical bit in a nonvolatile memory. To investigate the scaling opportunities of the resistive switching concept, physical models must be developed. This chapter summarizes the current state understanding of bipolar resistive switching, providing evidence for the voltage across the device being the controlling parameter for the CF growth during set. A physical model for set and reset transition is then described, allowing for an interpretation of the observed switching characteristics for different timescales. Finally, the open challenges for the scaling and the reliability of resistive switching memories are briefly summarized.

Several aspects of Atomic Force Microscopy (AFM) are considered in this chapter. Theoretical backgrounds of AFM, which are based on the asymptotic solution of tip–sample interactions, lead to the classification of modes and computer simulations of images and force curves. Visualization of surface morphology with high resolution is the main AFM application. The practical issues of the high-resolution imaging, tracking of corrugated surfaces, and compositional mapping of multicomponent polymers are illustrated in several examples. The components of heterogeneous systems are recognized by their specific shape or by their different mechanical and electric properties revealed in the AFM-based methods. The challenges of the quantitative nanomechanical studies of soft materials are discussed. The multifrequency examination of local electric/dielectric properties is presented by the single-pass studies of surface potential and dielectric response on various samples.