Modern Micro Research Articles

Elastic strain at interfaces and its influence on ionic conductivity in nanoscaled solid electrolyte thin films—theoretical considerations and experimental studies

Ionic transport in solids parallel to grain or phase boundaries is usually strongly enhanced compared to the bulk. Transport perpendicular to an interface (across an interface) is often much slower. Therefore in modern micro- and nanoscaled devices, a severe influence on the ionic/atomic transport properties can be expected due to the high density of interfaces.Transport processes in boundaries of ionic materials are still not understood on an atomic scale. In most of the studies on ionic materials the interfacial transport properties are explained by the influence of space charge regions. Here we discuss the influence of interfacial strain at semicoherent or coherent heterophase boundaries on ionic transport along these interfaces in ionic materials. A qualitative model is introduced for (untilted and untwisted) hetero phase boundaries. For experimental verification, the interfacial oxygen ionic conductivity of different multilayer systems consisting of cubic ZrO(2) stabilised by aliovalent dopands (YSZ, CSZ) and an insulating oxide is investigated as a function of structural mismatch. Recent results on extremely fast ionic conduction in YSZ/SrTiO(3) thin film systems ("colossal ionic concuctivity at interfaces") is discussed from the viewpoint of strain effects.

Developing nucleic acid-based electrical detection systems.

Development of nucleic acid-based detection systems is the main focus of many research groups and high technology companies. The enormous work done in this field is particularly due to the broad versatility and variety of these sensing devices. From optical to electrical systems, from label-dependent to label-free approaches, from single to multi-analyte and array formats, this wide range of possibilities makes the research field very diversified and competitive. New challenges and requirements for an ideal detector suitable for nucleic acid analysis include high sensitivity and high specificity protocol that can be completed in a relatively short time offering at the same time low detection limit. Moreover, systems that can be miniaturized and automated present a significant advantage over conventional technology, especially if detection is needed in the field. Electrical system technology for nucleic acid-based detection is an enabling mode for making miniaturized to micro- and nanometer scale bio-monitoring devices via the fusion of modern micro- and nanofabrication technology and molecular biotechnology. The electrical biosensors that rely on the conversion of the Watson-Crick base-pair recognition event into a useful electrical signal are advancing rapidly, and recently are receiving much attention as a valuable tool for microbial pathogen detection. Pathogens may pose a serious threat to humans, animal and plants, thus their detection and analysis is a significant element of public health. Although different conventional methods for detection of pathogenic microorganisms and their toxins exist and are currently being applied, improvements of molecular-based detection methodologies have changed these traditional detection techniques and introduced a new era of rapid, miniaturized and automated electrical chip detection technologies into pathogen identification sector. In this review some developments and current directions in nucleic acid-based electrical detection are discussed.

The Wage Curve: An Entry Written for the New Palgrave, 2nd Edition

This paper summarizes evidence for the existence of a wage curve - a downward-sloping relationship between the level of pay and the local unemployment rate - in modern micro data. At the time of writing, the curve has been found in 40 nations. Its elasticity is approximately -0.1.

GMR in Excess of 10% at Room Temperature and Low Magnetic Fields in Electrodeposited Cu/Co Nano-multilayer Structures

ABSTRACTElectrodeposition has emerged as a novel economically viable technique with large-scale production capabilities in modern day micro technologies. The current trends are to extend the potential of the electrodeposition to nano fabrication. We have successfully electrodeposited Cu/Co multilayers, exhibiting appreciably high GMR, on ITO as well as on Cu/Si substrates. Multilayer stacks with films in thickness range 1 – 10 nm were deposited. The Co layers have different mechanisms of growth on these substrates, thus resulting in different microstructure and topography of the electrodeposited films. This leads to different GMR behavior of the multilayers in both these cases. Room temperature GMR values of 15% at low fields are obtained on ITO substrate and higher values are possible on Cu/Si substrate.

Status and trends in modern micro- and nanotechnology

The recent development from micro- to nanotechnology enables new ideas and new physical effects to be implemented in both conventional and novel devices. Examples of fast developing fields in this context are electronic, photonic and magnetic components for sensor, memory, and logic applications. Optical lithography, the traditional path of patterning, is supplemented with sophisticated methods to access the nanoworld.

Marxism: Finding the Maestro in Management?

A survey of Marxist approaches to management theory reveals some shallowness in approach and little in the way of critiques of modern theory, either macro or micro. By moving through stages of looking at the class position of managers, Marxist interpretations to date, including that of Lenin as an advocate of Taylorism and the crystallising of management theory in opposition to Cold War communism, the paper sets the scene for an argument that Marxists should address management theory today and that management theory would be better for it.

Micro‐Structured Electrode Arrays: Characterization of High Frequency Discharges at Atmospheric Pressure

AbstractSummary: Micro‐structured electrode (MSE) arrays allow large area uniform glow discharges to be generated over a wide pressure range up to atmospheric pressure. Electrode widths, thicknesses and distances in the μm‐range are realized by means of modern micro machining and galvanic techniques. These electrode dimensions are small enough to generate sufficiently high electric field strengths to ignite gas discharges by applying only moderate radio frequency (RF, 13.56 MHz) voltages (80 V to 390 V in Ne, He, Ar, N2 and air). The non‐thermal plasma system can be characterized by a special probe measuring the electric parameters. MSE driven plasmas demonstrate different behavior from conventional RF or DC discharge plasmas. Due to the very small electrode gap width, d, the behavior of the charged particles in the RF field of our system could be described with the DC Townsend breakdown theory. Partially, dependent on the pressure range and type of gas, the breakdown mechanism was dominated by field electron emission or by a high frequency regime. The voltage‐current characteristic and electron density of the MSE plasma in He at atmospheric pressure were characteristic for a glow discharge. Using MSE arrays as plasma sources, several applications have been developed and successfully tested including atmospheric pressure plasma chemistry (decomposition of waste gases like CF4 and NO) and the sterilization of food packaging materials at atmospheric pressure.Voltage‐current characteristic of a 100 kPa He RF glow discharge generated with an MSE array (d = 70 μm).magnified imageVoltage‐current characteristic of a 100 kPa He RF glow discharge generated with an MSE array (d = 70 μm).

The Beginning of a Small Revolution

The Beginning of a <i>Small</i> Revolution

MINI-UAV REMOTE CONTROL: A CASE STUDY AT POLITECNICO DI TORINO

Recent development of modern micro and nano technologies allows aerospace vehicles extremely small size to be constructed. Wide availability and mass production of small dimension components drastically reduce the price of such vehicles. This fact allows them to be constructed by Universities and it makes them useful for education.

Mini-uav remote control: a case study at Politecnico di Torino

Abstract Recent development of modern micro and nano technologies allows aerospace vehicles extremely small size to be constructed. Wide availability and mass production of small dimension components drastically reduce the price of such vehicles. This fact allows them to be constructed by Universities and it makes them useful for education.

Ageing problems of the Inner Tracker of HERA-B – an example for new detectors and new effects

Large-size MSGCs and GEM-MSGCs were developed for HERA-B. In the course of R&D many ageing and operation problems have been found, several have been solved but some necessitated ‘bad’ compromises in order to obtain a working detector technology. Eventually, the satisfactory operation of 130 GEM-MSGCs in HERA-B proved the development to be successful. Many of the found problems do apply as well to other modern micro pattern gaseous detectors and recommendations for future R&D are derived.

Electronics and sensors based on pyroelectric AlGaN/GaN heterostructures

Electronic transport in semiconductors that possess high internal spontaneous and piezoelectric polarization opens up a new field of pyroelectronics and pyrosensors. The pyroelectric character of group-III-nitrides with wurtzite crystal structure yields a novel degree of freedom in designing and tailoring devices for modern micro- and nanoelectronic applications. Furthermore, spontaneous and piezoelectric polarization induced surface and interface charges can be used to develop very sensitive but robust sensors for the detection of ions, gases and polar liquids. We present a review of both theoretical and experimental studies of spontaneous and piezoelectric polarization present in AlGaN/GaN heterostructures as well as the electronic transport properties of polarization induced two-dimensional electron gases which are formed at the AlGaN/GaN interface due to the difference in the total polarization of two adjacent III-nitride layers. We demonstrate that the two-dimensional electron gases (2DEGs) achieved without modulation doping are very suitable as channel of high electron mobility transistors optimally suited for high power and high frequency applications (PART A) as well as for various kinds of sensors which can be operated in harsh environments (PART B). (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Superhard materials in the B/C/N system and modern micro system technology: synergistic effects

Diamond-like materials from the B/C/N system (e.g. diamond, tetrahedral amorphous carbon, cubic boron nitride (c-BN)) possess a great number of outstanding properties. Accordingly, they are very promising candidates for applications as active or passive layers in modern micro or nano systems, e.g. in probes for scanning probe microscopies (SPM). On the other hand, specially designed micro systems, in general, and SPM techniques especially, may help to overcome current problems in the optimization of existing thin films from the B/C/N system and in developing new ones by providing new techniques of material characterization, in the ideal case in situ during deposition. Therefore, synergistic effects may come into play, leading to a mutual improvement of both, the thin films and their properties, and the micro or nano systems. Although this ideal case has not yet been reached for films from the B/C/N system, we will present examples from our current research, which may eventually help to reach this aim. Fabrication of all-diamond tips and cantilevers for AFM applications, and of humidity sensors including carbon nitride films show the applicability of thin B/C/N films in micro systems, while the in situ characterization of diamond nucleation and growth by STM measurements and the measurements of the stress of c-BN films by micromachined silicon cantilevers demonstrate the usefulness of material characterization by modern micro systems.

Ternary optical computer principle

The fundamental principle and the characteristics of ternary optical computer, using horizontal polarized light, vertical polarized light and no-intensity to express information, are propounded in this paper. The practicability to make key parts of the ternary optical computer from modern micro or integrated optical devices, opto-electronic and electro-photonic elements is discussed. The principle can be applied in three-state optical fiber communication via horizontal and vertical polarized light.

Two- phase flow patterns and heat transfer in parallel microchannels

Microchannel heat sinks with two-phase flow can satisfy the increasing heat removal requirements of modern micro electronic devices. One of the important aspects associated with two- phase flows in microchannels is to study the bubble behavior. However, in the literature most of the reports present data of only a single channel. This does not account for flow mixing and hydrodynamic instability that occurs in parallel microchannels, connected by common inlet and outlet collectors. In the present study, experiments were performed for air- water and steam- water flow in parallel triangular microchannels with a base of 200–300 µ m. The experimental study is based on systematic measurements of temperature and flow pattern by infrared radiometry and high-speed digital video imaging. In air-water flow, different flow patterns were observed simultaneously in the various microchannels at a fixed values of water and gas flow rates. In steam-water flow, instability in uniformly heated microchannels was observed. This work develops a practical modeling approach for two-phase microchannel heat sinks and considers discrepancy between flow patterns of air- water and steam- water flow in microchannels.

The Education Premium in Canada and the United States

In the United States the education premium - the ratio of the earnings of university graduates to the earnings of high school graduates - has risen sharply in the last 20 years. Some economists and policymakers presume the same fact holds in Canada. Since so much of modern growth theory and micro- and macroeconomic policy turns on the education premium, it is important for social scientists and policymakers to know what has actually happened to the education premium. This paper argues that based on available evidence over the last 20 years the premium has been constant or has fallen in Canada.

DEPTH-RESOLVED SOFT X-RAY EMISSION SPECTROSCOPY OF Si-BASED MATERIALS

We discuss a soft X-ray emission (SXE) valence band (VB) spectroscopy method for the study of the electronic structure and chemical phase composition of solids in a near-surface region with depth resolution. The depth information is obtained by variation of the energy of the incident electron beam used to excite the SXE spectra. As the information depth can be varied from about 1 nm to 1 μm in silicon, this method is suitable for the investigation of materials of modern micro- and nanoelectronics. VB → core level (Si 2p or Al 2p) transitions in Si-based materials are used to demonstrate the technique. It was found that the contribution of the signal from the near-surface region (&lt; 1.5 nm) can be substantial (up to 50%) when the primary electron energy does not exceed the Si L 2,3 threshold by more than 150 eV. The technique is applied to Al impurities in a Si matrix, produced by ion implantation. The electronic structure at the Al sites and depth distribution of the Al impurity change markedly after postimplantation annealing. The observed electronic structure after annealing is in agreement with electronic structure calculations for substitutional Al impurities in a crystalline Si lattice.

Magnetic sensors for automotive applications

Magnetic sensors offer several key advantages: they allow contactless and, consequently, wear-free measurement of mechanical quantities like angle of rotation and angular speed. They are robust and inexpensive to manufacture. As one example of magnetic sensors in production at Robert Bosch GmbH, the steering wheel sensor LWS3 is shown, developed for the electronic stability program (ESP), which prevents vehicles from spinning. We recently demonstrated, that the inherent limitation of the AMR-effect to an 180° angular range can be overcome by using a switchable magnetic field generated inside the sensor element. For a new generation of magnetic sensors, the technology of giant magneto-resistance (GMR) thin film systems promises several advantages like larger working distances, more precise angular position measurement in a wider range (up to 360°), smaller and therefore cheaper sensor chips and economic system solutions due to the higher signal output. A GMR multilayer system of CoCu/Cu was developed, which fulfills the requirement of having no hysteresis in the magneto-resistive characteristics. On the other hand, research is still going on for sensitive GMR layers, which are stable at temperatures of 200°C (or more) for long time periods of at least 500 h. Thin film systems of spin valve type, used in read heads for disc drives, have been thoroughly evaluated about whether they can be used in sensors for automotive applications. The great challenge is to generate GMR thin film systems which cover a much wider range of features than the existing technologies of Hall and AMR and which can be produced at lower cost. Only versatile GMR sensors will lead to high production volumes, which are needed for a cost efficient fabrication as in other modern micro technologies.

The Impact of a Lignite Seam on Contaminated Groundwater in the Aquifer System of the Bitterfeld Region

Until 1990 the Bitterfeld region was heavily polluted by mining,an obsolete chemical industry and the uncontrolled deposition ofchemical wastes. The groundwater is extensivly contaminated inthe area of a disused chemical factory which once produced andapplied halogenated compounds on a large scale. At the researcharea in Bitterfeld, highly mobile chlorinated aliphatics andaromatics have been detected in both groundwater and sediments,especially in a lignite seam. The modern analytical method ofsolid-phase micro extraction (SPME) was successfully used toanalyse the pollution level of groundwater and sediments. Thelignite seam was found to have accumulated large quantities ofhalogenated hydrocarbons functioning as a giant adsorptionfilter, and hence recording past groundwater contamination.The vertical and lateral pollution profiles of sediments and thedistribution coefficients between lignite and groundwater atequilibrium conditions were determined for the key components.The consequences of the present situation for the progressivegroundwater quality of the quaternary aquifer are assessed in aforthcoming article.

Nanofabricated model catalysts. Manufacturing and model studies

Modern micro- and nano-fabrication methods provide a new avenue to prepare controlled model catalysts, which realistically mimic real supported catalysts. Such catalysts consist of 2D arrays of active catalysts deposited on active or inactive support materials. Particle size, shape, separation and support can be systematically varied. Such structures are easily accessible to scanning probe imaging and surface analysis techniques. This approach to build 2D analogues of supported catalysts is illustrated by Pt particles in the size range 10–500 nm deposited on alumina and ceria. The manufacturing technique, electron beam lithography and ‘lift-off’, is described. Its current limitations and future perspectives are discussed briefly.