TL;DR: A review of the literature on thermal transport in nanoscale devices can be found in this article, where the authors highlight the recent developments in experiment, theory and computation that have occurred in the past ten years and summarizes the present status of the field.
Abstract: Rapid progress in the synthesis and processing of materials with structure on nanometer length scales has created a demand for greater scientific understanding of thermal transport in nanoscale devices, individual nanostructures, and nanostructured materials. This review emphasizes developments in experiment, theory, and computation that have occurred in the past ten years and summarizes the present status of the field. Interfaces between materials become increasingly important on small length scales. The thermal conductance of many solid–solid interfaces have been studied experimentally but the range of observed interface properties is much smaller than predicted by simple theory. Classical molecular dynamics simulations are emerging as a powerful tool for calculations of thermal conductance and phonon scattering, and may provide for a lively interplay of experiment and theory in the near term. Fundamental issues remain concerning the correct definitions of temperature in nonequilibrium nanoscale systems. Modern Si microelectronics are now firmly in the nanoscale regime—experiments have demonstrated that the close proximity of interfaces and the extremely small volume of heat dissipation strongly modifies thermal transport, thereby aggravating problems of thermal management. Microelectronic devices are too large to yield to atomic-level simulation in the foreseeable future and, therefore, calculations of thermal transport must rely on solutions of the Boltzmann transport equation; microscopic phonon scattering rates needed for predictive models are, even for Si, poorly known. Low-dimensional nanostructures, such as carbon nanotubes, are predicted to have novel transport properties; the first quantitative experiments of the thermal conductivity of nanotubes have recently been achieved using microfabricated measurement systems. Nanoscale porosity decreases the permittivity of amorphous dielectrics but porosity also strongly decreases the thermal conductivity. The promise of improved thermoelectric materials and problems of thermal management of optoelectronic devices have stimulated extensive studies of semiconductor superlattices; agreement between experiment and theory is generally poor. Advances in measurement methods, e.g., the 3ω method, time-domain thermoreflectance, sources of coherent phonons, microfabricated test structures, and the scanning thermal microscope, are enabling new capabilities for nanoscale thermal metrology.
TL;DR: Electro-optic modulators are one of the most critical components in optoelectronic integration, and decreasing their size may enable novel chip architectures, and here a high-speed electro-optical modulator in compact silicon structures is experimentally demonstrated.
Abstract: Metal interconnections are expected to become the limiting factor for the performance of electronic systems as transistors continue to shrink in size. Replacing them by optical interconnections, at different levels ranging from rack-to-rack down to chip-to-chip and intra-chip interconnections, could provide the low power dissipation, low latencies and high bandwidths that are needed. The implementation of optical interconnections relies on the development of micro-optical devices that are integrated with the microelectronics on chips. Recent demonstrations of silicon low-loss waveguides, light emitters, amplifiers and lasers approach this goal, but a small silicon electro-optic modulator with a size small enough for chip-scale integration has not yet been demonstrated. Here we experimentally demonstrate a high-speed electro-optical modulator in compact silicon structures. The modulator is based on a resonant light-confining structure that enhances the sensitivity of light to small changes in refractive index of the silicon and also enables high-speed operation. The modulator is 12 micrometres in diameter, three orders of magnitude smaller than previously demonstrated. Electro-optic modulators are one of the most critical components in optoelectronic integration, and decreasing their size may enable novel chip architectures.
TL;DR: In this paper, the authors investigate the feasibility of achieving electrically driven lasing from individual nanowires and show that these structures can function as Fabry-Perot optical cavities with mode spacing inversely related to the nanowire length.
Abstract: Electrically driven semiconductor lasers are used in technologies ranging from telecommunications and information storage to medical diagnostics and therapeutics. The success of this class of lasers is due in part to well-developed planar semiconductor growth and processing, which enables reproducible fabrication of integrated, electrically driven devices. Yet this approach to device fabrication is also costly and difficult to integrate directly with other technologies such as silicon microelectronics. To overcome these issues for future applications, there has been considerable interest in using organic molecules, polymers, and inorganic nanostructures for lasers, because these materials can be fashioned into devices by chemical processing. Indeed, amplified stimulated emission and lasing have been reported for optically pumped organic systems and, more recently, inorganic nanocrystals and nanowires. However, electrically driven lasing, which is required in most applications, has met with several difficulties in organic systems, and has not been addressed for assembled nanocrystals or nanowires. Here we investigate the feasibility of achieving electrically driven lasing from individual nanowires. Optical and electrical measurements made on single-crystal cadmium sulphide nanowires show that these structures can function as Fabry-Perot optical cavities with mode spacing inversely related to the nanowire length. Investigations of optical and electrical pumping further indicate a threshold for lasing as characterized by optical modes with instrument-limited linewidths. Electrically driven nanowire lasers, which might be assembled in arrays capable of emitting a wide range of colours, could improve existing applications and suggest new opportunities.
TL;DR: In this article, a brief review of the theoretical state of the art in the field of semiconductor interfaces is presented; it is shown that the important factor controlling the different semiconductor barrier heights is the density of states associated with the semiconductor dangling-bonds.
Abstract: A brief review of the theoretical state of the art in the field of semiconductor interfaces is presented. Itis shown that the important factor controlling the different semiconductor barrier heights is the densityof states associated with the semiconductor dangling-bonds. Passivated semiconductor surfaces presentsaturated dangling-bonds and have modified barrier heights. Results for hydrogen-passivated GaAs(11O)-surfaces are presented; it is shown that the Schottky-barrier height formed by the deposition of a K-layeris sustantially changed by the hydrogen-passivation. 1 INTRODUCTION Interfaces of crystalline materials are at the heart of different devices, and their understanding is basic toan appropriate design of many microelectronic systems. In this regard, semiconductors and their interfaceswith other semiconductors or metals have received the major attention1 , and we shall concentrate ourdiscussion in this paper on analyzing their basic electronic properties and their relation to the formationof different barriers.There are, basically, two kinds of semiconductor contacts: metal- semiconductor2'3 and semiconductor-semiconductor interfaces4. A great deal of the recent research in this field has been addressed to under-standing how their different barrier heights depend on the properties of the crystals forming the contact5.Fig.1 shows the main parameters defining each barrier: (a) for a metal semiconductor interface,
TL;DR: In this paper, the authors consider novel ways of manufacturing functional circuits and devices based on techniques that are similar to printing visual information onto paper, and propose a solution-based selective deposition and direct-printing techniques.
Abstract: Impressive advances in vapor-phase deposition and photolithographic patterning techniques have been fueling the silicon microelectronics revolution over the last 40 years. However, for many interesting classes of materials, including biological materials or functional synthetic polymers, vacuum deposition and photolithography are not the techniques of choice for producing ordered structures and devices. Many of these materials selfassemble into well-ordered microstructures when deposited from solution, and patterning may be more readily achieved by solution-based selective deposition and direct-printing techniques. It is appealing to consider novel ways of manufacturing functional circuits and devices based on techniques that are similar to printing visual information onto paper.