Electric Barrier Research Articles

On the Time-Dependent Transport Mechanism Between Surface Traps and the 2DEG in AlGaN/GaN Devices

The physical mechanisms involved in the trapping and de-trapping processes associated with surface donor traps in gallium nitride (GaN) transistors are discussed in this paper. The paper challenges the conventional transient techniques adopted for extrapolating the trap energy level via experiments and TCAD simulations. Transient TCAD simulations were employed to reproduce the time-dependent electrical behavior of a metal-on-insulator field-effect transistor and explain the influence of the electric field and energy barrier on the transient time associated with the trapping and de-trapping mechanisms of surface traps. The comparison between three test structures and the relative variation of the trapping and de-trapping times with the bias and trap parameters leads to the suggestion of a proposed test structure and bias configuration to accurately extrapolate the energy level of surface traps in GaN transistors.

Kinetic features of collisionless sheaths around polarized cylindrical emitters from the orbital motion theory

The kinetic features of the sheath around a cylindrical emitter immersed in collisionless plasma at rest are analysed. After finding self-consistently the electric potential by applying the Orbital Motion Theory to the Vlasov-Poisson system, the local distribution functions are reconstructed and the radial profiles of important macroscopic quantities (plasma densities, currents, and temperatures) are then computed. It is found that there can only be three kinds of holes that are bound by three different boundaries—two related to the constraints from orbital effects and the other due to the electric potential barrier. The results are presented for three regimes: negative probe bias with monotonic and non-monotonic potential and positive probe bias with non-monotonic potential. To understand the variation of macroscopic-quantity radial profiles, three diagrams are presented for kinetic features: the ϵl-diagram for the integration domains of the two orbital invariants, the effective potential, and the local ...

Effects of tow transit on the efficacy of the Chicago Sanitary and Ship Canal Electric Dispersal Barrier System

Abstract In 2016, the U.S. Fish and Wildlife Service, U.S. Geological Survey, and U.S. Army Corps of Engineers undertook a field study in the Chicago Sanitary and Ship Canal near Romeoville, Illinois to determine the influence of tow transit on the efficacy of the Electric Dispersal Barrier System (EDBS) in preventing the passage of juvenile fish (total length

Making sense of the noise: The effect of hydrology on silver carp eDNA detection in the Chicago area waterway system

Environmental DNA (eDNA) sampling is an emerging tool for monitoring the spread of aquatic invasive species. One confounding factor when interpreting eDNA sampling evidence is that eDNA can be present in the water in the absence of living target organisms, originating from excreta, dead tissue, boats, or sewage effluent, etc. In the Chicago Area Waterway System (CAWS), electric fish dispersal barriers were built to prevent non-native Asian carp species from invading Lake Michigan, and yet Asian carp eDNA has been detected above the barriers sporadically since 2009. In this paper the influence of stream flow characteristics in the CAWS on the probability of invasive Asian carp eDNA detection in the CAWS from 2009 to 2012 was examined. In the CAWS, the direction of stream flow is mostly away from Lake Michigan, though there are infrequent reversals in flow direction towards Lake Michigan during dry spells. We find that the flow reversal volume into the Lake has a statistically significant positive relationship with eDNA detection probability, while other covariates, like gage height, precipitation, season, water temperature, dissolved oxygen concentration, pH and chlorophyll concentration do not. This suggests that stream flow direction is highly influential on eDNA detection in the CAWS and should be considered when interpreting eDNA evidence. We also find that the beta-binomial regression model provides a stronger fit for eDNA detection probability compared to a binomial regression model. This paper provides a statistical modeling framework for interpreting eDNA sampling evidence and for evaluating covariates influencing eDNA detection.

Conductance modulation in Weyl semimetals with tilted energy dispersion without a band gap

We investigate the tunneling conductance of Weyl semimetal with tilted energy dispersion by considering electron transmission through a p-n-p junction with one-dimensional electric and magnetic barriers. In the presence of both electric and magnetic barriers, we found that a large conductance gap can be produced with the aid of tilted energy dispersion without a band gap. The origin of this effect is the shift of the electron wave-vector at barrier boundaries caused by (i) the pseudo-magnetic field induced by electrical potential, i.e., a newly discovered feature that is only possible in the materials possessing tilted energy dispersion, (ii) the real magnetic field induced by a ferromagnetic layer deposited on the top of the system. We use a realistic barrier structure applicable in current nanotechnology and analyze the temperature dependence of the tunneling conductance. The new approach presented here may resolve a major problem of possible transistor applications in topological semimetals, i.e., the absence of normal backscattering and gapless band structure.

Excluding Feral Swine, Javelinas, and Raccoons from Deer Bait Stations

This paper presents a design, list of materials, and construction procedure for a physical and electric barrier fence to prevent feral swine (Sus scrofa), javelina (Pecari tajacu), raccoons (Procyon lotor), and perhaps other non-target animals from accessing or damaging bait stations designed to administer acaricide treatments for the prevention of cattle ticks, Rhipicephalus (Boophilus) microplus, and southern cattle ticks, R. (B.) annulatus, from successfully feeding on white-tailed deer (Odocoileus virginianus). The document includes behavioral rationale for the specific design, evidence of durability during deployment under field conditions in the brush country of southwestern Texas along the border with Mexico, and a demonstrated efficacy of 100%, as documented by photographic data gathered during this deployment. This study was undertaken specifically to aid in maximizing efforts of the USDA-Animal and Plant Health Inspection Service (APHIS) Cattle Fever Tick Eradication Program (CFTEP) and the Texas Animal Health Commission (TAHC) to control ticks feeding on white-tailed deer and will aid in preventing the re-introduction of cattle fever ticks and the potentially fatal Texas Fever that they vector from Mexico back into U.S cattle herds.

Spin and valley dependent line-type resonant peaks in electrically and magnetically modulated silicene quantum structures

A barrier with a tunable spin-valley dependent energy gap in silicene could be used as a spin and valley filter. Meanwhile, special resonant modes in unique quantum structure can act as energy filters. Hence we investigate valley and spin transport properties in the potential silicene quantum structures, i.e., single ferromagnetic barrier, single electromagnetic barrier and double electric barriers. Our quantum transport calculation indicates that quantum devices of high accuracy and efficiency (100% polarization), based on modulated silicene quantum structures, can be designed for valley, spin and energy filtering. These intriguing features are revealed by the spin, valley dependent line-type resonant peaks. In addition, line-type peaks in different structure depend on spin and valley diversely. The filter we proposed is controllable by electric gating.

Effect of Rashba and Dresselhaus Spin–Orbit Couplings on Electron Spin Polarization in a Hybrid Magnetic–Electric Barrier Nanostructure

A theoretical study has been carried out on the spin-dependent electron transport in a hybrid magnetic–electric barrier nanostructure with both Rashba and Dresselhaus spin–orbit couplings, which can be experimentally realized by depositing a ferromagnetic strip and a Schottky metal strip on top of a semiconductor heterostructure. The spin–orbit coupling-dependent transmission coefficient, conductance, and spin polarization are calculated by solving the Schrodinger equation exactly with the help of the transfer-matrix method. We find that both the magnitude and sign of the electron spin polarization vary strongly with the spin–orbit coupling strength. Thus, the degree of electron spin polarization can be manipulated by properly adjusting the spin–orbit coupling strength, and such a nanosystem can be employed as a controllable spin filter for spintronics applications.

Effect of electric field on carrier escape mechanisms in quantum dot intermediate band solar cells

Carrier escape and recombination from quantum dot (QD) states reduce the probability of two-step photon absorption (TSPA) by decreasing the available carrier population in the intermediate band (IB). In order to optimize the second photon absorption for future designs of quantum dot embedded intermediate band solar cells, the presented study combined the results of simulations and experiments to quantify the effect of electric field on the barrier height and the carrier escape from the QDs in InAs/GaAs quantum dot solar cells with five-layer QD superlattices. The electric field dependent effective barrier heights for ground state electrons were calculated using eight band k·p theory at short circuit conditions. With an increase in electric field surrounding the QDs from 5 kV/cm to 50 kV/cm, the effective barrier height of the ground state electrons was reduced from 147 meV to 136 meV, respectively. Thus, the increasing electric field not only exponentially enhances the ground state electron tunneling rate (effectively zero at 5 kV/cm and 7.9 × 106 s−1 at 50 kV/cm) but also doubles the thermal escape rate (2.2 × 1011 s−1 at 5 kV/cm and 4.1 × 1011 s−1 at 50 kV/cm). Temperature-dependent external quantum efficiency measurements were performed to verify that the increasing electric field decreases the effective barrier height. Additionally, the electric field dependent radiative lifetimes of the ground state were characterized with time-resolved photoluminescence experiments. This study showed that the increasing electric field extended the radiative recombination lifetime in the ground state of the QDs as a consequence of the reduced wave-function overlap between the electrons and holes. The balance of carrier escape and recombination determines the probability of TSPA.

Effects of vertical electric barrier on the behaviour of common carp

Effects of vertical electric barrier on the behaviour of common carp

Effects of strain on shot noise properties in graphene superlattices

In this paper the transmission and the shot noise properties through the strain-induced graphene superlattices are studied. It is found that for the zigzag direction strain the Fano factor shows a peak at new Dirac-like point and the position of the new Dirac point varies against the strain. Also, Fano factor has an oscillatory behavior with respect to strain strength and the oscillation period decreases by increasing the number of barriers. However, for the armchair direction strain the transmission can be blocked by the electric barrier and the Fano factor approaches 1, this is different from the zigzag direction strain.

Design Consideration of Diode-Type NAND Flash Memory Cell String Having Super-Steep Switching Slope

Effect of design parameters including device geometry, doping, and bias on key performance is investigated in a diode-type NAND flash memory cell string working under positive feedback (PF) mechanism. The string has a tube-type poly-Si channel, ${n} ^{+}$ and ${p} ^{+}$ regions on both ends of the string. A device simulator used in this paper is calibrated with measured trap density and poly-Si body parameters. It is shown that on-current of the PF diode-type cell string is affected significantly by electric junction barrier ( $V_{\mathrm{ EJB}} $ ) in the channel of the cell string. With different device dimensions, the PF diode-type cell string has almost constant, steep SS characteristic, but conventional FET-type cell string shows a large change in SS.

Introducing Electric Mobility in Latvian Municipalities: Results of a Survey

Electric mobility is a key technology towards the decarbonization of the transport sector. However, before achieving high rates of market penetration of electric vehicles several important barriers must be overcome. The aim of this research was to collect first experiences with electric vehicle use in a municipal fleet in Latvia. It was done through a survey designed for public authorities granted financial support for electric car purchase within a State support programme. The survey consisted of three groups of questions describing: (1) technical data of vehicle fleet; (2) user habits and attitudes, and; (3) motivation of the municipal authorities in switching to electric vehicles. Particular attention was paid to analysis of existing barriers for electric vehicle use and estimation of the necessary improvement rate to overcome these barriers. Respondents rated the lack of charging infrastructure and high initial cost as the two most significant delaying factors for electric vehicle use. Based on the responses, a price reduction by half would result in a notable reduction in the existing price barrier. Meanwhile in case of infrastructure, consumers are much less willing to accept any nuisance and require unrestricted access to the charging infrastructure in order to no longer consider the lack of it as a barrier.

Effect of barrier discharge on stability of electret state of high-density polyethylene

The electret state of high-density polyethylene subjected to an electric gas barrier of an AC discharge is studied. It is established that under the effect of the discharge a negative charge is formed on the film surface. Using thermally stimulated polarization, we study the space-charge processes in both the thermoand corono-electrets processed in the barrier discharge in the air gap between the dielectrics (glass–polyethylene). A comparison of the stability of the electret state in polyethylene films is carried out.

Bigheaded carps (Hypophthalmichthys spp.) at the edge of their invaded range: using hydroacoustics to assess population parameters and the efficacy of harvest as a control strategy in a large North American river

The threat posed by bigheaded carps (Hypophthalmichthys spp.) to novel ecosystems has focused efforts on preventing further range expansion; upstream progression in the Illinois River is a major concern due to its connection with the uninvaded Great Lakes. In addition to an electric barrier system, commercial harvest of silver carp (H. molitrix) and bighead carp (H. nobilis) in the upper river is intended to reduce propagule pressure and prevent range expansion. To quantify demographics and evaluate harvest efficacy, the upper river was sampled between 2012 and 2015 using mobile hydroacoustic methods. Reach-specific densities, size structures and species compositions varied interannually but the advancing population was characterized longitudinally as small-bodied, silver carp-dominated at the highest densities downstream, shifting to large-bodied, bighead carp-dominated at the low-density population front. The use of hydroacoustic sampling for harvest evaluation was validated in backwater lakes; there was a significant positive correlation between density estimates and the corresponding harvest catch-per-unit-effort of bigheaded carps. Localized densities of bigheaded carps were reduced by up to 64.4 % immediately post-harvest but generally rebounded within weeks. However, annual sampling of the entire upper river indicated that density of bigheaded carps decreased by over 40 % (between 2012 and 2013) and subsequently remained stable (between 2013 and 2014). The annual harvest of bigheaded carps increased during this period (from 45,192 to 102,453 individuals), in years of contrasting discharge conditions. At this spatiotemporal scale, harvest appears to have contributed to initial reduction, and subsequent maintenance of, bigheaded carps density levels, but discharge likely plays an important role (e.g., through immigration) in determining the extent of its impact. Mobile hydroacoustic sampling enabled robust quantification of the population over varying spatial scales and density gradients, highlighting the potential of this approach as an assessment tool for invasive fishes in riverine environments.

Fish distribution, abundance, and behavioral interactions within a large electric dispersal barrier designed to prevent Asian carp movement

We evaluated the abundance and behavior of wild fish within the electric barrier system in the Chicago Sanitary and Ship Canal. This electric barrier system serves to prevent the upstream migration of bighead carp (Hypophthalmichthys nobilis) and silver carp (Hypophthalmichthys molitrix) to Lake Michigan from the Illinois River. We found that fish were most abundant below the electric barrier during the summer and fall, were observed near areas of peak voltage, and sometimes persistently challenged the barrier. Fish were relatively scarce within the barrier system during the winter and spring. Fish that were able to penetrate the farthest into the barrier system were smaller and tended to aggregate at the water surface, near the canal walls. The accumulation of fish that we observed below the barrier, and the persistent challenging behavior, raises concerns about breaches any time the barrier is de-energized for maintenance or during intermittent power outages. Entrainment and breach caused by barges traversing the barrier are concerns as well because of the water movements they create and how they alter the electrical field.

Entrainment, retention, and transport of freely swimming fish in junction gaps between commercial barges operating on the Illinois Waterway

Abstract Large Electric Dispersal Barriers were constructed in the Chicago Sanitary and Ship Canal (CSSC) to prevent the transfer of invasive fish species between the Mississippi River Basin and the Great Lakes Basin while simultaneously allowing the passage of commercial barge traffic. We investigated the potential for entrainment, retention, and transport of freely swimming fish within large gaps (> 50 m3) created at junction points between barges. Modified mark and capture trials were employed to assess fish entrainment, retention, and transport by barge tows. A multi-beam sonar system enabled estimation of fish abundance within barge junction gaps. Barges were also instrumented with acoustic Doppler velocity meters to map the velocity distribution in the water surrounding the barge and in the gap formed at the junction of two barges. Results indicate that the water inside the gap can move upstream with a barge tow at speeds near the barge tow travel speed. Water within 1 m to the side of the barge junction gaps was observed to move upstream with the barge tow. Observed transverse and vertical water velocities suggest pathways by which fish may potentially be entrained into barge junction gaps. Results of mark and capture trials provide direct evidence that small fish can become entrained by barges, retained within junction gaps, and transported over distances of at least 15.5 km. Fish entrained within the barge junction gap were retained in that space as the barge tow transited through locks and the Electric Dispersal Barriers, which would be expected to impede fish movement upstream.

Effect of multi-domain structure on ionic transport, electrostatics, and current evolution in BaTiO3 ferroelectric capacitor

The semiconducting properties of certain ferroelectric materials, partially caused by the interactions among ferroelectric polarizations, charged domain walls, and conducting point defects, pose a threat to the reliability of ferroelectrics used as dielectric material in capacitor devices, and is not yet fully understood. We proposed a physical model combining the phase-field method for ferroelectric domain structures and diffusion equations for defect transport to study the resistance degradation behavior in multi-domain tetragonal BaTiO3 capacitors. We considered a hypothetical Ni/BaTiO3/Ni single parallel plate capacitor configuration subject to 0.5 V dc bias at 25 °C. It is found that 90° domain walls are charged, induce local space charge segregation, and form local electric potential barriers upon external bias that significantly influence the ionic transport behavior. Additionally, the 180° domain walls remain nearly charge neutral and have much less influence on ionic transport. The effect of domain wall and polarization orientations on the leakage current evolution is investigated. Our study could necessitate further understanding on the influence of ferroelectric state, ionic interactions, transport barriers, spatial distributions, and breakdown phenomena.

A low-voltage electric fish guidance system—NEPTUN

This paper presents a type of electric barrier for fish, which can be used to deter fish from water intakes and to guide them into fishpass channels. The barrier was designed to continuously generate an inhomogeneous low-voltage (50–80V) electric field. It consists of two arrays of steel electrodes (positive and negative) anchored to the substrate, with floating buoys attached at the top of each electrode to maintain their vertical position. Field strength increases continuously from the positive electrode array toward the negative electrodes. The resultant electric field does not stun fish, but stimulates their neuromuscular system, allowing them to escape. With input power of 0.43–0.45kWh and power consumption of 0.0018kWm−2, the system is inexpensive to operate, and safer for fish and other aquatic organisms than classic electric barrier designs. Laboratory tests of the barrier with 14 fish species of various sizes indicate that for flow velocities less than 0.20ms−1, 93.8–98.2% of the fish did not pass the NEPTUN barrier.

Effects of Electric Barrier on Passage and Physical Condition of Juvenile and Adult Rainbow Trout

Abstract Electric barriers can inhibit passage and injure fish. Few data exist on electric barrier parameters that minimize these impacts and on how body size affects susceptibility, especially to nontarget fish species. The goal of this study was to determine electric barrier voltage and pulse-width settings that inhibit passage of larger bodied rainbow trout Oncorhynchus mykiss (215–410 mm fork length) while allowing passage of smaller bodied juvenile rainbow trout (52–126 mm) in a static laboratory setting. We exposed rainbow trout to 30-Hz pulsed-direct current voltage gradients (0.00–0.45 V cm−1) and pulse widths (0.0–0.7 ms) and recorded their movement, injury incidence, and mortality. No settings tested allowed all juveniles to pass while impeding all adult passage. Juvenile and adult rainbow trout avoided the barrier at higher pulse widths, and fewer rainbow trout passed the barrier at 0.7-ms pulse width compared to 0.1 ms and when the barrier was turned off. We found no effect of voltage gradient on fish passage. No mortality occurred, and we observed external bruising in 5 (7%) juvenile rainbow trout and 15 (21%) adult rainbow trout. This study may aid managers in selecting barrier settings that allow for increased juvenile passage.