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There exist lots of impurities and micro-protrusions on the surface of metallic electrode, which lower the electron emission threshold. Since intense pulsed ion beam (IPIB) irradiation can melt and vaporize metal material, it is expected to increase the electron emission threshold by removing the impurities and micro-protrusions with this method. In our work, effects of IPIB treatment on electron emission threshold of metallic electrodes were studied. The electron emission threshold tests were done on a platform named 1 MV generator (the output voltage is higher than 1 MV with a rise time of ~25 ns when the load impedance $> 10~\Omega $). The pressure of the test vacuum chamber was kept at ~10−3 Pa. The results show that the electron emission threshold of as-machined 304L SS electrode was ~250 kV/cm, and it increased to 316 kV/cm after polish, and IPIB treatment enhanced the average electron emission threshold to 367 kV/cm. For bare machined aluminum electrodes, the average threshold was 255 kV/cm, and it also increased to 368 kV/cm after IPIB treatment. [ABSTRACT FROM AUTHOR]

A detailed analysis of power flow in superconductor-insulator-normal metal-insulator-superconductor (SINIS) structures with aluminum superconducting electrodes and normal metal absorber made of aluminum with suppressed superconductivity is carried out. From a comparison with the experimental results of measuring the current-voltage characteristics at temperatures from 0.087 K to 0.3 K, it was concluded that the power of the electron-phonon interaction is proportional to the difference of sixth powers of the electron and phonon temperatures. The previously applied relation with the difference of fifth powers leads to an almost twofold error in determining the power of the electron-phonon interaction and an estimate of the electron temperature that is underestimated by about 40 mK. [ABSTRACT FROM AUTHOR]

Solution-based deposition, with its simplicity and possibility for upscaling through printing, is a promising process for low-cost electronics. Metal oxide semiconductor devices, especially indium oxide with its excellent electrical properties, offer high performance compared to amorphous Si-based rivals, and with a form factor conducive to flexible and wearable electronics. Here, rectifying diodes based on an amorphous spin-coated indium oxide are fabricated for high-speed applications. We report a solution-processed diode approaching the UHF range, based on indium oxide, with aluminum and gold as the electrodes. The device was spin-coated from a precursor material and configured into a half-wave rectifier. The J – V and frequency behavior of the diodes were studied, and the material composition of the diode was investigated by X-ray photoemission spectroscopy (XPS). The 3-dB point was found to be over 700 MHz. The results are promising for the development of autonomously powered wireless Internet-of-Things systems based on scalable, low-cost processes. [ABSTRACT FROM AUTHOR]

Amorphous indium–gallium–zinc oxide (IGZO) is one of the most promising oxide semiconductors for thin-film transistors and it has started to replace amorphous silicon in display drivers. However, attempts to use IGZO in resistive random access memories (ReRAMs) are still scarce. This work investigates the bipolar resistive switching properties of crossbar-ReRAM devices based on IGZO thin film. Aluminum bottom electrode and two different top electrodes (i.e., Al and Ag) were tested in the devices. It was discovered that an oxygen plasma treatment (OPT) on the bottom electrode could significantly improve the surface roughness of the bottom electrode, the ON/OFF ratio, and the switching uniformity. After the OPT, the endurance of ReRAMs was enhanced. The ON/OFF current ratios reached ~104 and 105 within 100 endurance cycles for Al and Ag top electrode devices, respectively. Furthermore, the ReRAMs memory window remained nearly constant during a retention test of 105 s. The conduction mechanisms of the two device structures were examined using Schottky emission and space-charge-limited-current pictures, and the memory effect was explained by the formation and the interruption of filaments. [ABSTRACT FROM AUTHOR]

This paper addresses the importance of having control over the resistivity of the electrodes for capacitive micromachined ultrasonic transducers (CMUTs) devices. The electrode resistivity can vary depending on the fabrication technology used, and resistivity control becomes especially important in the cases where metal electrodes cannot be used. This raises the question: When is the resistivity of an electrode sufficiently low? To answer this question, we have developed a simple design criterion. The criterion describes the attenuation of ac signals along a CMUT element. It is shown that the nondimensional product between the angular excitation frequency, resistance, and capacitance ${\omega \textit {RC}}$ of an element has to be smaller than 0.35 to ensure an ac potential drop along the element of less than 1%. The optimal magnitude and directionality of the transmit pressure will be achieved if CMUT elements are designed according to the developed criteria. Hence, the model can be used to estimate device parameters that will ensure the CMUT is suitable for generating ultrasound images. An example is given where the model is used to predict the required electrode thickness for structured electrodes made of gold, aluminum, and indium–tin–oxide, respectively. To verify the model, two row-column addressed (RCA) CMUT transducers were used to illustrate the effect of high and low electrode resistivity. One transducer had a sufficient electrode resistivity, and the other had an insufficient electrode resistivity. The RCA CMUT transducers were fabricated using fusion bonding, where the top electrode is made of aluminum and the bottom electrode is made of doped silicon. The resistivity of the aluminum top electrode is ${2 \times 10^{-6}} \,\, {\Omega }$ cm for both transducers, whereas the resistivity for the bottom electrode is ${0.1} ~ {\Omega }$ cm for the first transducer and ${0.005} ~ {\Omega }$ cm for the second transducer. The transducer with low resistivity emits pressure uniformly along both the rows and columns, whereas the transmit pressure field from the other transducer has a uniformly distributed pressure field along the rows, but a decreasing pressure field along the columns due to the high resistivity in the bottom electrode. The pressure drop, along the columns, is frequency dependent and has been observed to be 63%, 74%, and 82% for the excitation frequencies 2, 4.5, and 7 MHz, respectively. [ABSTRACT FROM AUTHOR]

This letter presents for the first time the piezoresistive effect in p-type 4H–SiC. Longitudinal and transverse p-type 4H–SiC piezoresistors with a doping concentration of 10^18 cm ^-3 were fabricated along [ 1\overline 100 ] directions. Ni/Al electrodes annealed at 1000 °C showed a good ohmic contact, and then, the longitudinal and transverse gauge factors were found to be as high as 31.5 and −27.3, respectively. The large gauge factors, attributed to the change of valance energy bands upon application of mechanical strain, and the linear relationship between the resistance change versus induced strain demonstrate the potential of p-type 4H–SiC for mechanical sensing applications. [ABSTRACT FROM AUTHOR]

The first article in this series [1] covered the early history of electrolytic capacitors, from their invention around 1880 to the invention of the modern Al electrolytic capacitor structure in 1925. To summarize the early history, "valve metals" were recognized in the 1880s for their ability to conduct in one direction but impede current flow in the opposite direction as a result of oxide growth when submersed in an appropriate electrolyte. Early attempts to use the oxide as a dielectric so formed were frustrated by acidic electrolytes, which damaged the oxide layer and resulted in short capacitor life. Charles Pollak, a manufacturer of rechargeable batteries, realized the importance of the electrolyte and found that a neutral or basic electrolyte provides much greater stability of the oxide layer. In his 1896 German patent application for an electrolytic capacitor, Pollak described his invention as a "liquid condenser with aluminum electrodes, which are covered with a uniformly insulating layer generated by forming with a weak current, characterized by using an alkaline or neutral electrolyte. Since the insulating layer is very thin, the condenser has a very high capacitance and could be used as a polarized capacitor in a DC circuit." Early electrolytic capacitors consisted of an Al electrode in a "bath" of electrolyte. The resistance of the electrolyte resulted in a relatively high equivalent series resistance (ESR), and the capacitors were both bulky and heavy, although not relative to the alternatives at the time. Mains-operated radio receivers, introduced around 1927, created a large consumer market for capacitors, which were required to produce ripple-free DC voltages. Wax paper capacitors, limited to 1 or 2 μF, had to be combined with bulky chokes (inductors) to produce efficient power frequency filters. Electrolytic capacitors provided much greater capacitance so that the chokes were not necessary, but early electrolytic capacitors used in radio receivers still consisted of an oxidized anode in a bath of electrolyte. [ABSTRACT FROM PUBLISHER]

Atmospheric-pressure discharge in the tubular capillary plasma jet was studied to reveal the possibility to accelerate anodization of aluminum foils and fabricate alumina nanoparticles in liquid acids. Two different positions of the atmospheric pressure plasma jet relatively to the acid electrolyte and aluminum electrode were studied. Whereas at larger distances, only slight oxidation was obtained, the nanoporous surface and alumina nanoparticles were produced at closer (3–5 mm) distances. The mode with arcing (sparking) resulted in the film of alumina nanoparticles. The obtained results could be useful for the cheap and convenient synthesis of nanoparticles and nanostructured surfaces for various applications, including medical, biological, energy conversion, and nanoelectronic devices. [ABSTRACT FROM PUBLISHER]

The effect of metal electrodes on surface acoustic wave (SAW) properties in bulk semi-insulating Z-cut GaN crystal was measured for the first time. A SAW synchronous two-port resonator was used for these measurements. Such SAW parameters as velocity, electromechanical coupling coefficient, and reflection coefficient of a single reflecting strip were determined by matching the measured and calculated amplitude responses of the resonator for aluminum and gold electrodes at a frequency of about 240 MHz. It was found that for gold electrodes, the reflection coefficient of a single reflecting strip is much larger compared with that of aluminum. Changes of resonance frequency against temperature were measured in the temperature range from −20 °C to 80 °C and linear temperature coefficient of frequency of about −23 ppm/°C was obtained. Isotropic SAW properties in the propagation plane, low temperature coefficient of frequency, and possibility of integration with active devices make the bulk Z-cut GaN crystal attractive for practical applications. [ABSTRACT FROM PUBLISHER]

Two types of poly-Si thin-film transistors (TFTs) with the source (S) and drain (D) regions replaced by Al—metal-replaced junction TFT and self-aligned metal electrode (SAME) TFT—are characterized. Their IV characteristics are explained with a unified transport model based on the Schottky barriers at channel ends. Channel current is the sum of hole- and electron-current, which are limited by carrier injection via thermal emission or tunneling across the hole- and electron-barrier formed between poly-Si channel and metal S/D, respectively. The observed temperature dependence of transfer characteristics agrees well with the model. For SAME TFTs, barrier height of carrier transport is found to be modulated by a doped interfacial layer between the intrinsic poly-Si channel and Al electrodes at channel ends. By modulating the hole- and electron-barrier, three different types of device behaviors, such as p-type, n-type, and ambipolar TFTs can be obtained. Correlation between the doping effect and subthreshold swing and ON-state current, as well as channel length-dependent characteristics, are revealed. [ABSTRACT FROM PUBLISHER]

Transfer function of a shear horizontal acoustic plate mode (SHAPM) delay line with long interdigital transducers (IDTs) was derived using the scattering matrix method. Analytical expressions for the admittance, scattering coefficients, and reflection coefficient of the periodic electrodes of the IDT, derived previously for SAWs, were used for numerical calculations. By matching the measured and calculated amplitude responses, the velocity, electromechanical coupling coefficient, and reflection coefficient of an aluminum electrode on BT-cut quartz were determined. It was shown that for a sufficiently thick aluminum layer, a reasonable insertion loss could be achieved in spite of a very small electromechanical coupling coefficient. [ABSTRACT FROM PUBLISHER]

Low-density polyethylene (LDPE) films have been treated with titanium-tetrachloride vapor by means of the molecular-layer-deposition method. It is shown that such a treatment leads to a considerable improvement of the electret properties for both positively and negatively charged films. The temperature stability of the electret homo-charge has been increased by approximately 60°C. At the same time, the temporal stability of charge is also considerably improved. Modified low-density polyethylene films show no ?cross-over phenomenon? when charged to higher voltages. Thus, it is now possible to produce electrets from polyethylene films with high initial charge densities, but without a strongly reduced charge stability. The influence of a chemical treatment with titanium-tetrachloride vapor on charge injection from aluminum electrodes into polyethylene films was also investigated. It is found that the interface between an aluminum electrode and a modified LDPE surface layer has different injection properties for positive and negative charges. Electrons can be injected across the modified interface, whereas injection of holes is either very limited or non-existent. [ABSTRACT FROM PUBLISHER]

Deposition of high-k tantalum oxide thin films on thin polymer substrates was investigated, using low-temperature (-100 °C) pulsed-dc reactive sputtering. Degradation of two different polymers, polyethylene terephthalate (PET) and polypropylene (PP), were studied as a function of sputtering conditions. Two different deposition configurations have been explored for polymer films with aluminum electrode on one side. In one configuration, tantalum oxide was deposited on the nonelectroded side of the polymer, while in the other the deposition was on the electroded side of the polymer. The two fabricated structures have been characterized for dielectric permittivity, loss, and ac conductivity as a function of frequency and temperature. Sputtering tantalum oxide on the nonelectroded side of PET substrates results in a 37% higher permittivity for PET than the series model prediction of permittivity. Higher dielectric loss and ac conductivity accompany the higher permittivity. The a bulk relaxation in PET moves to slightly higher temperatures, indicating that there is an increase in the crystallinity of the bulk polymer. This observation is supported by the broader glass transition and an additional endothermic peak around 200 °C in PET/Ta2O5 compared to neat PET. In addition, modifications of the space charge activation energy in PET from 1.35 eV to 1.82 eV and of dc conductivity in PET from 6x 10-15 S/m to 4 x 10-14 S/m is observed. Sputtering Ta2O5 on the electroded side of the PET, under the same sputtering conditions, results in the formation of high-k tantalum oxide with dielectric permittivity, loss, and ac conductivity of 30, <5%, and 10-7 S/m at 1 kHz, respectively. [ABSTRACT FROM AUTHOR]

Theoretical analyses and designs of high-Q, quartz thin film resonators are presented. The resonators operate at an ultra-high frequency of 3.4 GHz for application to high-frequency timing devices such as cesium chip-scale atomic clocks. The frequency spectra for the 3.4-GHz thin film quartz resonators, which serve as design aids in selecting the resonator dimensions/configurations for simple electrodes, and ring electrode mesa designs are presented here for the first time. The thin film aluminum electrodes are found to play a major role in the resonators because the electrodes are only one third the thickness and mass of the active areas of the plate resonator. Hence, in addition to the material properties of quartz, the elastic, viscoelastic, and thermal properties of the electrodes are included in the models. The frequency-temperature behavior is obtained for the best resonator designs. To improve the frequency-temperature behavior of the resonators, new quartz cuts are proposed to compensate for the thermal stresses caused by the aluminum electrodes and the mounting supports. Frequency response analyses are performed to determine the Q-factor, motional resistance, capacitance ratio, and other figures of merit. The resonators have Q's of about 3890, resistance of about 1300 to 1400 ohms, and capacitance ratios of 1100 to 2800. [ABSTRACT FROM AUTHOR]

The quartz resonator Q with aluminum electrodes was studied with respect to its fundamental thickness shear mode frequency and its viscoelastic, viscopiezoelectric, and viscopiezoelectromagnetic behaviors. The governing equations for viscoelasticity, viscopiezoelectricity, and viscopiezo-electromagnetism were implemented for an AT-cut quartz resonator. To simulate the radiation conditions at infinity for the viscopiezoelectromagnetic model, perfectly matched layers over a surface enclosing the resonator were implemented to absorb all incident electromagnetic radiation. The shape of the radiation spectrum of a 5.6 MHz AT-cut quartz resonator was found to compare relatively well the measured results by Campbell and Weber. The mesa-plate resonator was studied for a frequency range of 1.4 GHz to 3.4 GHz. The resonator Q was determined to be influenced predominantly by the quartz viscoelasticity; how- ever at frequencies greater than 2.3 GHz, the quartz electromagnetic radiation had an increasingly significant effect on the resonator Q. At 3.4 GHz, the electromagnetic radiation accounted for about 14% of the loss in resonator Q. At frequencies less than 2 GHz, the calculated resonator Q compared well with the intrinsic Qx provided by the formula Qx = 16 x 106/f where f was in MHz. At frequencies higher than 2.3 GHz, the aluminum electrodes had significant effects on the resonator Q. At 3.4 GHz, the electromagnetic radiation loss in the electrodes was an order of magnitude greater than their viscoelastic loss; hence, the vibrating aluminum electrodes became an efficient emitter of electromagnetic waves. The effects of electrical resistance in both the electrodes and quartz were determined to be negligible. [ABSTRACT FROM AUTHOR]

A miniaturized microfluidic device was developed to facilitate electromanipulation of bacterial respiratory pathogens. The device comprises a microchip with circular aluminum electrodes patterned on glass, which is housed in a microfluidic system fabricated utilizing polydimethylsiloxane. The device provides sample preparation capability by exploiting positive dielectrophoresis (DEP) in conjunction with pulsed voltage for manipulation and disruption of Bordetellapertussis bacterial cells. Positive DEP capture of B. pertussis was successfully demonstrated utilizing 10 V[subrms] and 1MHz ac fields. Application of dc pulses (300 V amplitude and 50 μs pulsewidth applied 1 s apart) across the aluminum electrodes resulted in electrodisruption and lysis of B. pertussis bacterial cells. Real-time polymerase chain reaction, a 2[sup3] factorial experimental design and transmission electron microscopy were used to evaluate bacterial cell manipulation and factors affecting bacterial cell disruption. The main factors affecting bacterial cell disruption were electric field strength, the electrical conductivity of the cell suspension sample, and the combined effect of number of pulses and sample conductivity. The bacterial deoxyribonucleic acid target remained undamaged as a result of DEP and cell lysis experimentation. Our findings suggest that a simple miniaturized microfluidic device can achieve important steps in sample preparation on-chip involving respiratory bacterial pathogens. [ABSTRACT FROM AUTHOR]

Planar metal-semiconductor-metal (MSM) photodetectors with very thin hydrogenated amorphous silicon (a-Si) films were fabricated for the detection of ultraviolet (UV) radiation. Since DNA and proteins strongly absorb UV radiation, these detectors find application in DNA and protein detection. The performance of top and bottom electrode MSM structures with aluminum electrodes is compared. The measured results include a responsivity of 150 mA/W and an external quantum efficiency of 74% at a wavelength of 260 nm for the top electrode configuration at a bias of 2 V/μm and a 10-μm finger spacing. [ABSTRACT FROM AUTHOR]

Electric field / space charge profiles obtained using the laser-intensity-modulation-method (LIMM) are presented for XLPE samples machined from power cable insulation cross-linked using dicumyl peroxide. The samples, 110 μm thick with vacuum-evaporated aluminium electrodes, were subjected to dc fields of 48 kV/mm and both polarities at room temperature for at least 24 hr. The LIMM measurements were made at room temperature, and at various times after the end of poling. Electric field and space charge profiles obtained using the scale-transformation and polynomial regularization methods were in fair quantitative agreement over much of the sample thickness, except when the electric field showed a maximum or minimum. Simulation data for assumed electric field profiles strongly suggested that the polynomial regularization method is more accurate. Most of the space charge was concentrated near the electrodes, with densities of order 5–10 C m-3 in those regions. Charge of the same sign tended to accumulate adjacent to a given physical electrode, for both poling polarities. [ABSTRACT FROM AUTHOR]

Organic capacitors are among the most significant applications of conductive polymers, allowing the realization of lightweight and flexible dispositives. The main drawback of completely organic capacitors is the very low dielectric rigidity, due to the irregular surface of the polymer-polymer interface. This paper describes our hybrid solution using aluminum electrodes, with the very important characteristic of easy connection between contacts of the discrete dispositive and electrodes. Chemical, technological, and functional tests have been conducted to estimate the effective values of this device, and natural properties of self-healing and nonpolarity have been investigated. [ABSTRACT FROM PUBLISHER]

Abstract-We realized an organic electrical memory device with a simple structure based on single-layer pentacene film embedded between Al and ITO electrodes. The optimization of the thickness and deposition rate of pentacene resulted in a reliable device with an on/off current ratio as high as nearly 10[sup6], which was two orders of magnitude higher than previous results, and the storage time was more than 576 h. The current transition process is attributed to the formation and damage of the interface dipole at different electric fields, in which the current conduction showed a transition from ohmic conductive current to Fowler-Nordheim tunneling current. After the transition from ON- to OFF- state, the device tended to remain in the OFF-state even when the applied voltage was removed, which indicated that the device was very promising for write.once read.many.times memory. [ABSTRACT FROM AUTHOR]

We present an organic electrically bistable memory device based on the molecular complex film composed of tetracyanoquinodimethane and a soluble methanofullerene derivative [6,6]-phenyl C61-butyric acid methyl ester. The device has an Al/molecules/Al sandwich-like structure. The molecular layer was formed by spin-coating technique instead of expensive vacuum deposition method. The current-voltage characteristics show that the device switches from the initial ‘low’ conduction state to ‘high’ conduction state upon application of external electric field at room temperature. The on/off ratio is up to 106. Either state has been found to remain stable for more than five months, even after the external electric field is removed. The device presented is of potential use for low-cost write-once-read-many-times memory applications. [ABSTRACT FROM AUTHOR]

Nanotip-enhanced microplasma devices have been successfully fabricated and operated with neon gas at room temperature. The panel-type microplasma device included nanotip and metal electrodes on the rear panel, which provided low discharge voltage, strong emission, and stable discharge phenomena. The nanotip with a radius below 10 nm enhances the electrical field distribution density. The electrical properties of neon discharges have been examined with pulsed waveforms from 2 to 20 kHz in neon with pressures from 4 × 104 to 105 Pa. [ABSTRACT FROM AUTHOR]