Dielectric breakdown induced by picosecond laser pulses

The damage thresholds of transparent optical materials were investigated. Single picosecond pulses at 1.06 microns, 0.53 microns and 0.35 microns were obtained from a mode locked Nd-YAG oscillator-amplifier-frequency multiplier system. The pulses were Gaussian in space and time and permitted the determination of breakdown thresholds with a reproducibility of 15%. It was shown that the breakdown thresholds are characteristic of the bulk material, which included nine alkali halides, five different laser host materials, KDP, quartz, sapphire and calcium fluoride. The extension of the damage data to the ultraviolet is significant, because some indication was obtained that two- and three-photon absorption processes begin to play a role in determining the threshold. Throughout the visible region of the spectrum the threshold is still an increasing function of frequency, indicating that avalanche ionization is the dominant factor in determining the breakdown threshold. This was confirmed by a detailed study of the damage morphology with a high resolution microscope just above the threshold. The influence of self focusing is discussed, and evidence for beam distortion below the power threshold for complete self focusing is presented, confirming the theory of Marburger

Integrated optomechanics and single-photon detection in diamond photonic integrated circuits

The development of quantum computers and quantum simulators promises to provide solutions to problems, which can currently not be solved on classical computers. Finding the best physical implementation for such technologies is an important research topic and using optical effects is a promising route towards this goal. It was theoretically shown that optical quantum computing is possible using only single-photon sources and detectors, and linear optical circuits. An experimental implementation of such quantum optical circuits requires a stable, robust and scalable architecture. This can be achieved via miniaturization of the optical devices in the form of photonic integrated circuits (PICs). The development of a suitable material platform for such PICs could therefore have a large impact on future technologies. Diamond is a particularly attractive material here, as it naturally offers a range of optically active defects, which can act as single-photon sources, quantum memories, or sensor elements. Besides its excellent optical properties, diamond also has a very high Young's modulus, which is important for optomechanics, and can be employed for potentially fast and low-loss tuning of PICs after fabrication. In this work, components for future quantum optical circuits are developed. This includes the first diamond optomechanical elements, as well as the first integrated single-photon detectors on a diamond material platform. Diamond micromechanical resonators with high quality factors are realized and their actuation via optical gradient forces and electrostatic forces is demonstrated. The accomplished superconducting nanowire single-photon detectors show excellent performance in terms of low timing jitter, high detection efficiency, and low noise-equivalent power. Moreover, a novel scalable method for PIC fabrication from high quality single crystal diamond is presented.Comment: PhD thesis at the department of physics of the Karlsruhe Institute of Technology (KIT), Advisors: Prof. Dr. Martin Wegener and Prof. Dr. Wolfram Pernice. 152 pages, 84 figure

Index to NASA tech briefs, 1971

The entries are listed by category, subject, author, originating source, source number/Tech Brief number, and Tech Brief number/source number. There are 528 entries

Characterization of advanced etching reactors using novel diagnostic tools

Plasma etching equipment used for sub-micron integrated circuit fabrication at present are exclusively based on 13.56 MHz, capacitively coupled, parallel-plate geometry. The underlying mechanisms of plasma processes in these reactors are not well understood and there is even less understanding of how the etch-tool parameters relate to the plasma discharge characteristics which actually determine the etch process. In this thesis, new diagnostic techniques were applied for the characterization and optimization of plasma etching processes in various reactor configurations. Specifically, diode and triode configurations were studied extensively using tuned scanning Langmuir probes. Both radial and axial distributions of plasma density were measured for a range of process parameters. Extensive mapping of plasma region in these reactors have shown that the plasma density distribution is dramatically different for dissociative molecular etching gases as compared to inert gases. Furthermore, the density distribution was found to be strongly dependent on the electronegativity of the process gas. In the triode configuration, the relative phase between the RF voltage waveforms applied to the electrodes was found to determine both the magnitude and distribution of the plasma density. Typically, higher etch-rates and better etch-uniformity were obtained for out-of-phase excitation(180°) as compared with the in-phase excitation(0°) in the triode. The understanding gained by these studies has lead to the development of a novel magnetic multipole based triode reactor configuration. This new reactor configuration can be operated at low pressures and produces high-rate, low damage etching of submicron features with required profile control. In addition, a new plasma etching diagnostic technique based on thermal imaging of wafer was developed. The technique has been found to be useful for in situ real-time monitoring of end-point and uniformity of etching as well as for inferring wafer temperature and heat transfer characteristics. Also, a simple end-point detection technique based on plasma impedance monitoring was developed which eliminates the need for optical access to the wafer/plasma

Interface Circuits for Microsensor Integrated Systems

ca. 200 words; this text will present the book in all promotional forms (e.g. flyers). Please describe the book in straightforward and consumer-friendly terms. [Recent advances in sensing technologies, especially those for Microsensor Integrated Systems, have led to several new commercial applications. Among these, low voltage and low power circuit architectures have gained growing attention, being suitable for portable long battery life devices. The aim is to improve the performances of actual interface circuits and systems, both in terms of voltage mode and current mode, in order to overcome the potential problems due to technology scaling and different technology integrations. Related problems, especially those concerning parasitics, lead to a severe interface design attention, especially concerning the analog front-end and novel and smart architecture must be explored and tested, both at simulation and prototype level. Moreover, the growing demand for autonomous systems gets even harder the interface design due to the need of energy-aware cost-effective circuit interfaces integrating, where possible, energy harvesting solutions. The objective of this Special Issue is to explore the potential solutions to overcome actual limitations in sensor interface circuits and systems, especially those for low voltage and low power Microsensor Integrated Systems. The present Special Issue aims to present and highlight the advances and the latest novel and emergent results on this topic, showing best practices, implementations and applications. The Guest Editors invite to submit original research contributions dealing with sensor interfacing related to this specific topic. Additionally, application oriented and review papers are encouraged.

Index to 1986 NASA Tech Briefs, volume 11, numbers 1-4

Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1986 Tech Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

The Design, Fabrication and Characterization of Independent-Gate FinFETs

The Independent-Gate FinFET is introduced as a novel device structure that combines several innovative aspects of the FinFET and planar double-gate FETs. The IG-FinFET addresses the concerns of scaled CMOS at extremely short channel lengths, by offering the superior short channel control of the double-gate architecture. The IG-FinFET allows for the unique behavioral characteristics of an independent-gate, four-terminal FET. This capability has been demonstrated in planar double-gate architectures, but is intrinsically prohibited by nominal FinFET integration schemes. Finally, the IG-FinFET allows for conventional CMOS manufacturing techniques to be used by leveraging many of the FinFET integration concepts. By introducing relatively few deviations from a standard FinFET fabrication process, the IG-FinFET integration offers the capability of combining three-terminal FinFET devices with four-terminal IG-FinFET devices in one powerful technology for SoC or Analog/RF application, to name only a few. The IG-FinFET device is examined by device modeling, circuit simulation, testsite design, fabrication and electrical characterization. The results of two-dimensional device simulations are presented, and the effects of process variations are discussed in order to understand the desire for a fully self-aligned double-gate architecture. Circuit design is investigated to demonstrate the capabilities of such a double-gate device. Physical designs are also examined, and the layout penalties of implementing such a device are discussed in order to understand the requirement of double-gate and independent-gate integration. A test vehicle is designed and presented for the structural integration and fabrication process development necessary for the demonstration and validation of this novel device architecture. The processing and results of several fabrication experiments are presented, with physical and electrical analysis. The integration changes and process modifications suggested by this analysis are discussed and analyzed. Fabricated devices are then electrically and physically characterized. The final set of fabricated devices show excellent agreement with simulated devices, and experimental verification of double-gate device theory. The results of this work provide for a new and novel device architecture with wide ranging technology application, as well as a new fabrication platform with which to study double-gate device theory and further technology integration

Electromagnetic Composites: from Effective Medium Theories to Metamaterials

Electromagnetic (EM) composites have stimulated tremendous fundamental and practical interests owing to their flexible electromagnetic properties and extensive potential engineering applications. Hence, it is necessary to systematically understand the physical mechanisms and design principles controlling EM composites. In this tutorial, we first provide an overview of the basic theory of electromagnetism about electromagnetic constitutive parameters that can represent the electromagnetic properties of materials. We show how this corpus allows a consistent construction of effective medium theories and allows for numerical simulation of EM composites to deal with structure-property relationships. We then discuss the influence of spatial dispersion of shaped inclusions in the material medium on the EM properties of composites, which has not been systematically illustrated in the context of this interdisciplinary topic. Next, artificial composites or metamaterials with peculiar properties not readily available in nature are highlighted with particular emphasis on the control of the EM interaction with composites. We conclude by discussing appropriate methods of electromagnetic measurement and practical aspects for implementing composites for specific applications are described. Overall, this tutorial will serve the purpose of introducing the basics and applications of electromagnetic composites to newcomers in this field. It is also anticipated that researchers from different backgrounds including materials science, optics, and electrical engineering can communicate to each other with the same language when dealing with this interdisciplinary subject and further push forward this advancement from fundamental science to technological applications.Comment: 63 pages, 20 figure