共查询到20条相似文献,搜索用时 421 毫秒
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Dede M Urkmen K Girişen O Atabak M Oral A Farrer I Ritchie D 《Journal of nanoscience and nanotechnology》2008,8(2):619-622
Scanning Hall Probe Microscopy (SHPM) is a quantitative and non-invasive technique for imaging localized surface magnetic field fluctuations such as ferromagnetic domains with high spatial and magnetic field resolution of approximately 50 nm and 7 mG/Hz(1/2) at room temperature. In the SHPM technique, scanning tunneling microscope (STM) or atomic force microscope (AFM) feedback is used to keep the Hall sensor in close proximity of the sample surface. However, STM tracking SHPM requires conductive samples; therefore the insulating substrates have to be coated with a thin layer of gold. This constraint can be eliminated with the AFM feedback using sophisticated Hall probes that are integrated with AFM cantilevers. However it is very difficult to micro fabricate these sensors. In this work, we have eliminated the difficulty in the cantilever-Hall probe integration process, just by gluing a Hall Probe chip to a quartz crystal tuning fork force sensor. The Hall sensor chip is simply glued at the end of a 32.768 kHz or 100 kHz Quartz crystal, which is used as force sensor. An LT-SHPM system is used to scan the samples. The sensor assembly is dithered at the resonance frequency using a digital Phase Locked Loop circuit and frequency shifts are used for AFM tracking. SHPM electronics is modified to detect AFM topography and the frequency shift, along with the magnetic field image. Magnetic domains and topography of an Iron Garnet thin film crystal, NdFeB demagnetised magnet and hard disk samples are presented at room temperature. The performance is found to be comparable with the SHPM using STM feedback. 相似文献
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A single-electron transistor (SET) can be used as an extremely sensitive charge detector. Mechanical displacements can be converted into charge, and hence, SETs can become sensitive detectors of mechanical oscillations. For studying small-energy oscillations, an important approach to realize the mechanical resonators is to use piezoelectric materials. Besides coupling to traditional electric circuitry, the strain-generated piezoelectric charge allows for measuring ultrasmall oscillations via SET detection. Here, we explore the usage of SETs to detect the shear-mode oscillations of a 6-mm-diameter quartz disk resonator with a resonance frequency around 9 MHz. We measure the mechanical oscillations using either a conventional DC SET, or use the SET as a homodyne or heterodyne mixer, or finally, as a radio-frequency single-electron transistor (RF-SET). The RF-SET readout is shown to be the most sensitive method, allowing us to measure mechanical displacement amplitudes below \(10^{-13}\) m. We conclude that a detection based on a SET offers a potential to reach the sensitivity at the quantum limit of the mechanical vibrations. 相似文献
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I. Hafaiedh S. Helali K. Cherif A. Abdelghani G. Tournier 《Materials science & engineering. C, Materials for biological applications》2008,28(5-6):584-587
Recently, oxide semiconductor material used as transducer has been the central topic of many studies for gas sensor. In this paper we investigated the characteristic of a thick film of tin dioxide (SnO2) film for chemical vapor sensor. It has been prepared by screen-printing technology and deposited on alumina substrate provided with two gold electrodes. The morphology, the molecular composition and the electrical properties of this material have been characterized respectively by Atomic Force Spectroscopy (AFM), Fourier Transformed Infrared Spectroscopy (FTIR) and Impedance Spectroscopy (IS). The electrical properties showed a resistive behaviour of this material less than 300 °C which is the operating temperature of the sensor. The developed sensor can identify the nature of the detected gas, oxidizing or reducing. 相似文献
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为了提高NO2气体检测的灵敏度和速度,以单壁碳纳米管(SWCNT)为装配介质,采用介电电泳方法获得单壁碳纳米管场效应晶体管(SWCNT—FET)作为气体传感器检测装置,通过原子力显微镜(AFM)和扫描电子显微镜(SEM)表征,结果显示,利用介电电泳方法能够成功地把SWCNTs装配到芯片的源漏两极间;通入NO2气体前后电特性变化情况的测试结果表明,选择接入电场频率为2MHz,峰峰值电压10V,介电电泳持续时间10s时,制备出SWCNT—FET成功率高,通入NO2气体后的电导率增加三个数量级。利用紫外光持续照射10min,SWCNT上的气体分子解附,使气体传感器可重复利用。 相似文献
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The application of nematic liquid crystal infiltrated photonic crystal fiber as a sensor for electric field intensity measurement is demonstrated. The device is based on an intrinsic sensing mechanism for electric fields. The sensor probe, which consists of a 1 cm infiltrated section of photonic crystal fiber with a lateral size of ~125 μm, is very compact with small size and weight. A simple all-fiber design for the sensor is employed in an intensity based measurement scheme. The transmitted and reflected power of the infiltrated photonic crystal fiber is shown to have a linear response with the applied electric field. The sensor is operated in the telecommunication window at 1550 nm. The temperature dependence of the device at this operating wavelength is also experimentally studied and discussed. These structures can be used to accurately measure electric field intensity and can be used for the fabrication of all-fiber sensors for high electric field environments as both an in-line and reflective type point sensor. 相似文献
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Alex Henning Michel Molotskii Nandhini Swaminathan Yonathan Vaknin Andrey Godkin Gil Shalev Yossi Rosenwaks 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(37):4931-4937
Scanning gate microscopy is used to determine the electrostatic limit of detection (LOD) of a nanowire (NW) based chemical sensor with a precision of sub‐elementary charge. The presented method is validated with an electrostatically formed NW whose active area and shape are tunable by biasing a multiple gate field‐effect transistor (FET). By using the tip of an atomic force microscope (AFM) as a local top gate, the field effect of adsorbed molecules is emulated. The tip induced charge is quantified with an analytical electrostatic model and it is shown that the NW sensor is sensitive to about an elementary charge and that the measurements with the AFM tip are in agreement with sensing of ethanol vapor. This method is applicable to any FET‐based chemical and biological sensor, provides a means to predict the absolute sensor performance limit, and suggests a standardized way to compare LODs and sensitivities of various sensors. 相似文献
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This paper reviews several full adder (FA) designs in single-electron technology (SET). In addition to the structure and size (i.e., number of devices), this paper tries to provide a quantitative and qualitative comparison in terms of delay, sensitivity to (process) variations, and complexity of the design. This will allow for a better understanding of the advantages and disadvantages of each solution. An optimization of an SET FA (combining one of the SET FAs with a static buffer), together with a new SET FA design (based on capacitive SET threshold logic gates), will also be described and compared with the other SET FAs. 相似文献
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Emerging nanotechnologies, like single-electron tunneling (SET) technology, possesses properties that are fundamentally different from what CMOS offers to engineers. This opens up avenues for novel computational paradigms, which can perform arithmetic operations efficiently by utilizing these new available properties. In this line of reasoning, in this paper we investigate the implementation of division in SET technology using a novel computation paradigm called electron counting. First, we present two schemes that are based on sequential approximation of the quotient. The first scheme is basic and simple to build, but suffers from overshoot and has a rather large delay. The second scheme, which is a modification of the first one, has a delay logarithmic in the quotient magnitude and the simulation results we present indicate that this scheme works correctly. Finally, we propose a division scheme based on the computation of periodic symmetric functions. Although this scheme requires a varactor for which no nanoscale implementation yet exists and which cannot be directly simulated, it demonstrates the possibilities that nanotechnology, and specifically SET technology, potentially offers as it has a time complexity of O(1). 相似文献
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Plasmonic metal nanostructures are widely used as subwavelength light concentrators to enhance light harvesting of organic solar cells through two photophysical effects, including enhanced local electric field (ELEF) and antenna‐amplified light scattering (AALS), while their adverse quenching effect from surface energy transfer (SET) should be suppressed. In this work, a comprehensive study to unambiguously distinguish and quantitatively determine the specific influence and contribution of each effect on the overall performance of organic solar cells incorporated with Ag@SiO2 core–shell nanoparticles (NPs) is presented. By investigating the photon conversion efficiency (PCE) as a function of the SiO2 shell thickness, a strong competition between the ELEF and SET effects in the performance of the devices with the NPs embedded in the active layers is found, leading to a maximum PCE enhancement of 12.4% at the shell thickness of 5 nm. The results give new insights into the fundamental understanding of the photophysical mechanisms responsible for the performance enhancement of plasmonic organic solar cells and provide important guidelines for designing more‐efficient plasmonic solar cells in general. 相似文献
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Gutierrez-Martinez C. Santos-Aguilar J. 《IEEE transactions on instrumentation and measurement》2008,57(7):1362-1368
In this paper, a wideband-electric-field-sensing scheme that uses optically matched integrated optics electrooptic devices and coherence modulation of light is described. In a coherence modulation scheme, the integrated optics sensor detects the electric field and imprints it around an optical delay. The optical delay is generated by a birefringent optical waveguide in a lithium niobate (LiNbO3) integrated optics two-wave interferometer. The modulated optical delay, acting as an information carrier, is transmitted through an optical fiber channel. At the receiver, light is demodulated by a second integrated optics two-wave interferometer, which also introduces a second optical delay. The optical delays on the sensor and demodulator are matched at the same value. The integrated optics demodulator measures the autocorrelation of light around the optical delay value, and the imprinted electric field is recuperated as a linear variation of the received optical power. The matching of the sensor and demodulator allows a direct detection of the electric field, giving a unique feature to this fiber-integrated optics scheme. The experimental setup described here uses two pigtailed LiNbO3 electrooptic crystals: one acting as the electric field sensor and the other acting as the optical demodulator. The wideband sensing range on the experimental setup corresponds to frequencies between 0 and 20 kHz. 相似文献
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Tseng AA 《Small (Weinheim an der Bergstrasse, Germany)》2011,7(24):3409-3427
Atomic force microscopy (AFM) has been an effective material removing tool for fabricating various nanostructures because of its sub-nanometer precision and simplicity in operation. AFM material removing techniques have evolved from a solely mechanical process to one in which the tip can be loaded by additional energy sources, such as thermal, electric, or chemical, to enhance its fabrication abilities. In this paper, these material removing techniques are reviewed with an emphasis on their capabilities and recent progress. The recent hardware and software developments are first presented to provide a general view on the current status of the technology to be assessed. Following an overview of the feasibility and effectiveness of using mechanical scratching for removing various types of soft and hard materials, the processes of a wide range of approaches using multiple tip sources are then assessed with a focus on their principles, versatilities, and potentials for future applications. 相似文献
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The control of the growth of silicon dioxide (SiO(2)) and the formation of quantum dots (QDs) play an important role in the fabrication of single-electron transistors (SETs). In this work, SET?structures were fabricated using a systematic oxidation technique known as the pattern-dependent oxidation (PADOX) process. For comparison, two oxidation processes using conventional furnace and rapid thermal processing (RTP) were used. The oxidation temperature for both oxidation processes was set at 1000?°C and the oxygen flow rate in the furnace was set at 1?l?min(-1). The nanostructures were characterized using AFM, SEM and TEM to determine the quality and the stoichiometry of the Si QDs and the oxides. The oxidation rate using a furnace is 0.36?nm?s(-1), significantly lower than the RTP value which is 2.16?nm?s(-1). Meanwhile, the oxygen contents in SiO(2) grown by furnace and RTP are approximately the?same. 相似文献
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以SET 因素为导向的移动电源产品设计和开发 总被引:5,自引:3,他引:2
以Integrated New Product Developmen(tINPD)程序中的SET因素为启示,分析了移动电源产品所面临的社会趋势(S)、经济动力(E)、技术进步(T)以及生产商所处的行业背景、企业自身的优势、市场现有产品价格、形态的关系,对移动电源产品进行市场机会分析和方案设计。提出了产品机会是从SET的共同作用下引发的新趋势中得以实现的,而机会又需要被解释为和产品功能、外形相关的具体形式要素,明确产品机会并将其转化为具体的产品在产品开发过程中非常重要。 相似文献
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A new analytical modelling approach to evaluate the impact of single event transients (SETs) on CMOS circuits has been developed. The model allows evaluation of transient pulse amplitude and width (duration) at the logic level, without the need to run circuit level (Spice-like) simulations. The SET mechanism in MOS circuits is normally investigated by Spice-like circuit simulation. The problem is that electrical simulation is time-consuming and must be performed for each different circuit topology, incident particle and track. The availability of a simple model at the logic gate level may greatly improve circuit sensitivity analysis. The electrical response of a circuit to an ionising particle hit depends on many parameters, such as circuit topology, circuit geometry and waveform shape of the charge injection mechanism. The proposed analytical model, which is accurate and computer efficient, captures these transistor-level effects of ionising particle hits and models them to the logic level of abstraction. The key idea is to exploit a model that allows the rapid determination of the sensitivity of any logic gate in a CMOS circuit, without the need to run circuit simulations. The model predicts whether or not a particle hit generates a SET, which may propagate to the next logic gate or memory element, making possible to analyse the sensitivity of each node in a complex circuit. Model derivation is strongly related to circuit electrical behaviour, being consistent with technology scaling. The model is suitable for integration into CAD tools, intending to make automated evaluation of circuit sensitivity to SET possible, as well as automated estimation of soft error rate 相似文献
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Shimizu K. Endo H. Matsumoto G. 《IEEE transactions on instrumentation and measurement》1989,38(3):779-784
In a study of biological effects of extremely-low-frequency (ELF) electric fields, a few techniques were developed which make it possible to measure the electric field at a biological body surface with practical accuracy and spatial resolution. The following techniques were developed: pressing down a field sensor against the body surface using a thin flexible sensor: and covering the body surface with a conductive layer while leaving the point of measurement uncovered. The characteristics of these techniques were also examined with a view toward practical applications, such as the measurement of the electric field at a human surface located under high-voltage transmission lines 相似文献
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This paper discusses a new methodology for characterizing the magnetic properties of ferromagnetic materials. The method
uses an alternating electric current to periodically magnetize ferromagnetic materials. The periodic magnetization generates
a high-frequency electric potential noise between two electrodes within the excitation circuit. The magnetically induced electric
potential noise (MIPN) is related to the discontinuous processes that occur during magnetization similar to magnetic Barkhausen
noise. This paper discusses the results of several experiments that measured both electric potential noise and Barkhausen
noise signal. A comparison of the results showed that the MIPN correlates directly to magnetic Barkhausen noise. The MIPN
signal is small when compared to Barkhausen noise, but it is still easy to measure under laboratory conditions. Therefore,
MIPN could be an efficient technique for materials characterization and sensor technology, for example, as fiber stress sensors
in a composite aircraft component. 相似文献