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In the present paper, we investigate the electronic transport properties of hybrid biphenyl molecular junctions by employing ab-initio self-consistent density functional theory (DFT) and non-equilibrium Green’s functions (NEGF) technique. In the hybrid system, biphenyl molecule is bridging between different left and right electrodes via thiol (SH) and Copper (Cu) chemical groups respectively. In model A, hybrid biphenyl is connected to left and right pristine zigzag graphene nanoribbon (ZGNR) electrodes. In models B and C, hybrid biphenyl is connected to pristine ZGNR electrode in left side, while one-edge Cu-doped and both-edge Cu-doped ZGNR electrode in right side respectively. The higher current value is found for model C than that of models A and B for higher positive applied bias. Moreover, a very strong rectification effect has been revealed in models B and C. The DFT-calculated transmission characteristics further supports the observed current findings. Our results will provide a new scientific and engineering understanding to enable the rectifying performance that can be used for next generation nano-rectifier devices and other nano-electronic applications.

This paper presents the use of Taguchi method in the optimization process of a Self-switching Diode (SSD) as a Terahertz rectifier to obtain the optimal parameters for rectification. The rectification performance is mainly contributed by a parameter known as curvature coefficient, γ which is derived from the current-voltage (I-V) behavior of the device and can be altered by varying the device’s geometrical structure. The parameters involved are the channel length, channel width and trenches width of the device, and the rectification performance are observed based on the peak of γ and its corresponding bias voltage. Using Taguchi method for design of experiment (DOE), effects on the interaction among these parameters are investigated by employing the orthogonal array and evaluation of the signal-to-noise (S/N) ratio both in the peak of γ and its corresponding bias voltage. The proposed parameters using this method showed γ peak of 32 V−1 and 30 V−1 at DC bias of 30 mV and zero-bias, respectively.

When RF waves are applied in tokamaks with metal walls, sheath rectification effects associated with the fields induced in the scrape-off layer (SOL) may lead to enhanced plasma-wall interactions (i.e. heat-loads in the limiters, RF-induced impurity sources) which can endanger the integrity of the machine and limit the RF power. Currently, some numerical tools are being used to simulate the RF antenna near fields in the presence of magnetized plasmas, but they have their limitations. Some neglect completely the interaction of the RF waves with the low-density plasma close to the antenna. Others take into account these interactions, but generate numerical spurious oscillations around the Lower Hybrid Resonance (LHR). Simplifications to reach convergence had also been tried (e.g. neglect gyrotropy, increase electron density to avoid the LHR), but the fields obtained with these simplifications can be very different to the real ones and this difference can affect the accuracy of derived magnitudes which use these fields as an input (e.g. sheath rectification effects). In this work we try to overcome all the limitations mentioned above by customizing the open-source finite element code ERMES. This code implements a finite element formulation which allows to simulate the near fields of the RF antenna in a continuous gyrotropic non-homogeneous media without limits in the minimum value of the plasma density and provides stable solutions even in the presence of the LHR. Benchmarking of this approach is underway and comparison against measurements, semi-analytical approaches and other codes will be presented.

In this work, we have fabricated the nanostructured p-Si/n-TiO2 hetero-junction diode by using a facile spin-coating method. The XRD analysis suggests the presence of well crystalline anatase TiO2 film on Si with small grain size (∼16 nm). We have drawn the band alignment using Anderson model to understand the electrical transport across the junction. The current-voltage (J-V) characteristics analysis reveals the good rectification ratio (103 at ± 3 V) and slightly higher ideality factor (4.7) of our device. The interface states are responsible for the large ideality factor as Si/TiO2 form a dissimilar interface and possess a large number of dangling bonds. The study reveals the promises to be used Si/TiO2 diode as an alternative to the traditional p-n homo-junction diode, which typically require high budget.

Molecular electronics is one of the alternative solution to the problem in miniaturization of conventional silicon based electronic devices. Rectification effect produced by conventional semiconductor based devices utilized in various application. A study has been done to show the rectification effect occurs in gold/2,5-dicholorobenzene-1,3-dithiol/gold single molecular junction. For that, we have investigated the electron transport of Au/2,5-dicholorobenzene-1,3-dithiol/ Au single molecular junction. The metal molecular junction was constructed by linking sulfur atom of 2,5-dicholorobenzene-1,3-dithiol to gold at fcc site. Density Functional Theory (DFT) with Non-Equilibrium Green’s Function (NEGF) was used to calculate total density of states, projected density of states, transmission co-efficient, electrode potential, conductance, spectral current and current-voltage characteristic of Au/2,5-dicholorobenzene-1,3-dithiol/Au. Based on first principle calculation of this molecular junction, it was observed that 2,5-dicholorobenzene-1,3-dithiol can be used as a single molecule rectifier.

CuxZnyS thin films were deposited by two chemical methods, i.e., electrochemical deposition and photochemical deposition.CuxZnyS shows p-type conductivity when the Cu content in the film is larger than 1 %, and it has a wide bandgap (> 3eV) with its composition Zn-rich. The as-deposited films are amorphous. Heterostructures were fabricated with ZnS and ZnO as the n-type partner. Rectification properties were observed for both the heterostructures, which demonstrates that CuxZnyS can be useful for optoelectronic devices such as transparent solar cells and UV sensors.CuxZnyS thin films were deposited by two chemical methods, i.e., electrochemical deposition and photochemical deposition.CuxZnyS shows p-type conductivity when the Cu content in the film is larger than 1 %, and it has a wide bandgap (> 3eV) with its composition Zn-rich. The as-deposited films are amorphous. Heterostructures were fabricated with ZnS and ZnO as the n-type partner. Rectification properties were observed for both the heterostructures, which demonstrates that CuxZnyS can be useful for optoelectronic devices such as transparent solar cells and UV sensors.

This paper presents a power electronic devices application focus on modeling, analysis, and control of switching power converter in the inverting DC substation with regenerative braking system which is used to recycle the surplus regenerative power by feed it back to the main AC grid. The main objective of this research is to improve the switching power electronic converter of the railway inverting substation and optimize the maximum kinetic energy recovery together with minimum power losses from the railway braking system. Assess performance including efficiency and robustness will be evaluated in order to get the best solution for the design configuration. Research methodology included mathematical calculation, simulation, and detail analysis on modeling of switching power converter on inverting substation. The design stage separates to four main areas include rectification mode, regenerative mode, control inverter mode and filtering mode. The simulation result has shown that the regenerative inverter h...

By introducing a funnel-shape semiconductor channel to create an asymmetrical energy barrier profile, a type of nonlinear device has been proposed and simulated which is referred as planar barrier diode (pbd). An applied voltage v across a pbd provides different height of the barrier depending on the sign of v. This results in a nonlinear current-voltage characteristic that resembles a typical diode behavior and therefore it can be used in signal rectification. The intrinsic cut-off frequency obtained in the simulation of the p-type silicon pbd rectifier was ∼15 ghz.

Cleaning of laser mirrors made of copper, its alloys and similar materials from operational and technological contamintions by mechanical rubbing using conventional solvents may be accompanied by scratches. Non-contact cleaning has its disadvantages, such as low efficiency of solvents and instability of their properties during storage and use. The diagnostics of the threshold of optical breakdown, the lifetime of the operation of mirrors and the strength of the coatings applied on them made it possible to find azeotropic mixtures of more effective solvents. In this paper, methods of stabilizing their physicochemical properties are investigated and proposed. Stabilization of halogenated hydrocarbons occurs with a decrease in the boiling temperature and an increase in stability during rectification purification of contaminated solvents for reuse by applying azeotropic mixtures based on them. We have shown that it is efficient to use azeotropic mixtures based on halogenated halogen-substituted hydrocarbon-acetone (2-butanone) -ethanol for the purification of metal optics. Such azeotropic mixtures are the most effective cleaning media, which retain stability of properties and ensure maximum and rapid removal of impurities without damage to the surface.

The flow behaviour and performance parameters of a diffuser-nozzle element of a valveless micropump have been investigated for different driving pressure frequencies. When a fluctuating pressure is imposed on the inlet boundary of a diffuser-nozzle element, there is a net flow in diffuser direction due to the dynamic effect. The variation of this net flow along with rectification capacity, and diffuser efficiency has been investigated for different frequencies of driving pressure. Flow behaviour and recirculation region due to dynamic effect have been studied as qualitative study. Pressure and velocity have been analyzed for quantitative analysis and for validation with results found in literature. 2-D geometry has been used in the present study. 3-D geometry has been modeled to justify the results obtained from 2-D analysis. Five different pressure frequencies ranging from 5 kHz to 50 kHz have been used to investigate their effects on the performance of diffuser-nozzle element in high frequency ranges. The net flow and performance of the nozzle-diffuser element are found to be decreasing with the increasing frequency. The performance is found to be less sensitive to frequency at high pressure range (above 30 kHz).

An organic-inorganic junction was fabricated by forming [Ru(Cy2PNHCH2-C4H3O)(η6-p-cymene)Cl2] complex thin film using spin coating technique on n-Si and evaporating Au metal on the film. It was seen that the structure had perfect rectification property. Current-voltage (I-V) measurements were carried out in dark and under various illumination conditions (between 50-100 mW/cm2) and with the temperature range from 303 to 380 K. The structure showed unusually forward and reverse bias temperature and light sensing behaviors. It was seen that the current both in forward and reverse bias increased with the increase in light intensity and temperature.

The educational method which is including designing, making, and evaluating actual semiconductor devices with learning the theory is one of the best way to obtain the fundamental understanding of the device physics and to cultivate the ability to make unique ideas using the knowledge in the semiconductor device. In this paper, the simplified Boron thermal diffusion process using Sol-Gel material under normal air environment was proposed based on simple hypothesis and the feasibility of the reproducibility and reliability were investigated to simplify the diffusion process for making the educational devices, such as p-n junction, bipolar and pMOS devices. As the result, this method was successfully achieved making p+ region on the surface of the n-type silicon substrates with good reproducibility. And good rectification property of the p-n junctions was obtained successfully. This result indicates that there is a possibility to apply on the process making pMOS or bipolar transistors. It suggests that there is a variety of the possibility of the applications in the educational field to foster an imagination of new devices.

The optical absorption of ZnO nanorod had been reduced by introducing Mn as doping element. In this present study the optical absorption of ZnO nanorod has been improved by simultaneous doping of the element Mn and Cu. The hydrothermal reaction was adopted for the synthesis. The electrical conductivity and the optical band gap of the Mn0.04Cu0.05Zn0.91O were measured as 1.16 × 10−3Scm−1 and 3.07eV respectively, assigned the semiconductor behavior. The light induced rectification in time dependent current response characteristic of Al/ Mn0.04Cu0.05Zn0.91O/ITO was investigated to check the performance of the composite in opto-electronic switching device.

The current-voltage (I-V) characteristics of Au/Y/p-InP/Pt Schottky barrier diode (SBD) are analyzed at room temperature. The Au/Y/p-InP/Pt SBD shows a good rectification behavior. The ideality factor (n), barrier height (Φb), series resistance (Rs) and shunt resistance (Rsh) are determined from the I-V measurements. The n and Φb values of Au/Y/p-InP/Pt SBD are found to be 1.32 and 0.62 eV respectively. The value of barrier height (BH) obtained from Norde function is compared with those calculated from Cheung’s functions. The series resistance (Rs) is calculated from Cheung’s and modified Norde functions. Additionally, it is found that n, Φb, Rs, and Rsh have strong correlation with the applied bias. Furthermore, at low and high voltage regions, ohmic and space-charge-limited conduction mechanisms are found to govern the current flow in the diode.

RF sheaths rectification can be the reason for operational limits for Ion Cyclotron Range of Frequencies (ICRF) heating systems via impurity production or excessive heat loads. To simulate this process in realistic geometry, the Self-consistent Sheaths and Waves for Ion Cyclotron Heating (SSWICH) code is a minimal set of coupled equations that computes self-consistently wave propagation and DC plasma biasing. The present version of its wave propagation module only deals with the Slow Wave assumed to be the source of RF sheath oscillations. However the ICRF power coupling to the plasma is due to the fast wave (FW). This paper proposes to replace this one wave equation module by a full wave module in either 2D or 3D as a first step towards integrated modelling of RF sheaths and wave coupling. Since the FW is propagative in the main plasma, Perfectly Matched Layers (PMLs) adapted for plasmas were implemented at the inner side of the simulation domain to absorb outgoing waves and tested numerically with tilted BD in Cartesian geometry, by either rotating the cold magnetized plasma dielectric tensors in 2D or rotating the coordinate vector basis in 3D. The PML was further formulated in cylindrical coordinates to account for for the toroidal curvature of the plasma. Toroidal curvature itself does not seem to change much the coupling. A detailed 3D geometrical description of Tore Supra and ASDEX Upgrade (AUG) antennas was included in the coupling code. The full antenna structure was introduced, since its toroidal symmetry with respect to the septum plane is broken (FS bars, toroidal phasing, non-symmetrical structure). Reliable convergence has been obtained with the density profile up to the leading edge of antenna limiters. Parallel electric field maps have been obtained as an input for the present version of SSWICH.

We have fabricated an n-p nanorods (NRs) heterojunction consisting of n-type ZnO NR and p-type CuInS2 by a simple, low cost solution method through an ion-exchange route. The heterojunction shows a rectifying behavior with an ideality factor of 1.66. Furthermore, the heterojunction is promising candidates for applications in electro-optic devices.

In this paper we present reverse rectification behavior of an organic heterojunction comprising of nickel phthalocyanine (NiPc) and copper-hexadecafluroro-phthalocyanine (F16CuPc) grown by MBE. Using Kelvin Probe we found that charge is accumulated at both side of interface, electrons in F16CuPc and holes in NiPc. The thickness of charge accumulated at the interface is about 20 nm. Based on Kelvin Probe data, mechanism of reverse rectification is explained.

With the wide application of high performance cryo-pumps, high and low temperature superconducting devices, MRI, infrared detectors and cryogenic electronics, the development of high efficient and reliable 10 K G-M refrigerator is of critical importance and awaited by cryogenic industries. In the past two years, systematic studies have been carried out, and detailed experimental tests indicated that the cooling performance of the 10 K G-M refrigerator was improved by adding two additional rectification meshes inside the low temperature regenerator and by optimizing the system charge pressure. Furthermore, a new labyrinth sealing displacer was proposed and fabricated to substitute the traditional piston-ring sealing displacer for improved operating stability and reliability of the 10 K GM refrigerator. The detailed experimental results and improvements were summarized and their optimal cases were given in this paper.

In 2005 we introduced a laser-based ultrasonic (LBU) receiver based on multi-channel random-quadrature (MCRQ) detection. MRCQ receiver was specifically developed to meet the demanding needs of industrial inspections where operating conditions are far from ideal. We showed that by integrating detector arrays into a classic interferometer design, we can transform a high-sensitivity but delicate laboratory interferometer into a rugged system capable of enduring tough industrial environment. MCRQ detection can be implemented using either a free-space or a fiber optical designs, without reduction in performances. Initially, the ultrasonic information was extracted with simple and very robust signal processing based on high-pass filtering followed by signal rectification. We recently introduced a new demodulation scheme which allows for linear detection. Linear detection is based on phase-flip correction achieved via lock-in detection of a known perturbation signal.

The design of an Ion Cyclotron (IC) launcher is essentially driven by its coupling properties and its capability of maintaining low parallel electric fields in front of it, indeed providing good power transfer to plasma and avoiding unwanted phenomena such as sheath rectification or hot spots. Both aspects are deeply related to the adopted geometry and the loaded plasma model; the systematic usage of TOPICA code [1], able to precisely take into account a realistic antenna geometry and an accurate plasma description, could certainly help in understanding which elements may have a not negligible effect on the antenna design. This paper presents a detailed comparison, carried out with TOPICA code, between a simplified flat version of one of the IC antennas installed in ASDEX Upgrade experiment and its real curved geometry. The advantages and disadvantages of both geometrical representations are outlined in terms of power transferred to the plasma and with a specific focus on sheath driving potentials. To complete the overview, the importance of an accurate plasma description is also exploited.

To investigate the onset of thermal rectification in graded mass systems, we study the classic and quantum self‐consistent harmonic chain of oscillators. We show that rectification is absent in the classic, but present in the quantum chain. We note the ingredient of rectification, and its existence in this simple model indicates that rectification may be an ubiquitous phenomenon.

Rectification of microwave radiation (20–40 GHz) by a line boundary between two two‐dimensional electron systems on a silicon surface is observed and investigated for different temperatures, electron concentrations, and microwave powers. We propose that the origin of the rectification is the thermoelectric effect due to strong local overheating of the electrons by the microwaves near the boundary. The distributions of electric potential, microwave field and electron temperature are obtained by solving a kinetic equation for the hot electrons together with Maxwell’s equations. Excellent quantitative agreement is obtained between theory and experiment.

We demonstrate transverse tunable ballistic rectification in a density‐modulated two‐dimensional electron gas (2DEG). A transverse voltage in the direction of the density‐gradient is observed, i.e. perpendicular to the applied source‐drain voltage. The polarity of the transverse voltage is independent of the polarity of the source‐drain voltage demonstrating rectification in the device. We find that the transverse voltage is also proportional to the difference of the reciprocal of the carrier densities in the density‐modulated 2DEG.

It is shown that the shapes of acoustic radiation-induced static strain and displacement pulses (rectified acoustic pulses) are defined locally by the energy density of the generating waveform. Dispersive properties are introduced analytically by assuming that the rectified pulses are functionally dependent on a phase factor that includes both dispersive and nonlinear terms. The dispersion causes an evolutionary change in the shape of the energy density profile that leads to the generation of solitons experimentally observed in fused silica.

In this work we explore a high frequency collective phenomenon present in an asymmetric nanodiode. Charge fluctuations in the space‐charge regions around the channel become visible in the noise spectra at a characteristic frequency. Though dealing with a specific noise mechanism, by virtue of the particular geometry of the device, this phenomenon enhances the DC response of the diode to AC signals, originating a THz resonance at a frequency that can be tuned by the geometry. Taking place at room temperature, this effect can be exploited to design somewhat frequency‐selective detectors in the THz domain. The use of different narrow bandgap materials (like InGaAs, InAs or InSb) in the channel and the influence of the operation temperature are analyzed in order to improve the resonance characteristics.

Distributed thermal loads are frequently encountered in large deployable structures used in space applications such as optical mirrors and focal plane electronics. An innovative mechanism for providing distributed cooling is an oscillatory pulse-tube cryocooler that is integrated with a fluid rectification system consisting of check-valves and buffer volumes in order to extract a small amount of continuous flow. This continuous flow allows relatively large loads to be accepted over a long distance.An additional advantage of the rectified system is the ability to provide rapid and precise temperature control via modulation of the flow rate in the flow loop. This paper presents an experimental demonstration of this temperature control method. A rectified interface is integrated with a thermal load and subjected to various thermal disturbances. Temperature regulation is enabled using temperature feedback control of a valve placed in the distribution loop. The control parameters are selected to meet temperatu...

We present a new type of a ballistic rectifier where electrons are injected under zero injection angle into a straight central voltage stem of a four‐terminal Si/SiGe junction. For small input current a sign reversal of the rectified output signal is found which depends reversibly on the voltage applied to two side gate electrodes.

We report on an enhanced efficiency of inertial‐ballistic rectification in a cascade of rectifier stages. Each rectifier stage is composed of a pair of current injecting branches which oppositely merge into a central voltage stem. The voltages obtained at both ends of the stem enable to separate inertial‐ballistic and mode‐controlled rectification. In a cascade composed of two rectifier stages the total inertial‐ballistic signal is enhanced compared to the single contributions while the mode‐controlled signal is almost unaffected.

We measure Coulomb drag between parallel quantum wires which have the same length but are slightly displaced from each other along the wire direction. We observe a rectified Coulomb drag in which sign of the drag voltage is the same, independent on the current direction in the drive‐wire, under the conditions of strong correlation, i.e., low electron density, high magnetic field and low temperature. From this experiment, we conclude the formation of Wigner crystal and discuss the non‐linear motion of Wigner crystal in the drag‐wire induced by an electrostatic potential from the adjacent drive‐wire.

Rectification effects relying on ballistic electron transport properties in InAs/AlGaSb mesoscopic structures are reported. We fabricated and characterized InAs/AlGaSb ballistic rectification devices consisting of two voltage probes and two current‐injection waveguide structures slanted to the voltage probes without anti‐dot. In one of the devices, waveguide structures were introduced into one of the voltage probes. We compare the DC rectification characteristics at various temperatures ranging from 4.2 K to 300 K. The enhanced rectification effects were observed up to 300 K in the device which has additional waveguide structure in the voltage probe.

Schottky barrier contacts have been formed by electron beam evaporation of Pd onto the polar (0001)‐ and the nonpolar (1010)‐face of hydrothermally grown n‐type single‐crystalline ZnO. On both surfaces the contacts can be operated under reverse bias voltages up to −5 V. Thereby, the Pd/(1010)‐ZnO system exhibits a larger rectification of the current than the Pd/(0001)‐ZnO system. CV profiling reveals a nonuniform carrier concentration in the range between ∼ 2 × 1015 cm−3 and ∼ 5 × 1017 cm−3, depending on surface orientation.

In this paper we review two basic and related mechanisms rectifying fluctuations: Brownian ratchets and paradoxical games. We focus our study on the effect of control in both ratchets and games.

The current-voltage curve of an InSb device was measured at low temperature down to 0.42 K. Rectifying characteristics became obvious at 2 K and below. This result suggests the possible use of InSb as a substrate for a radiation detector with high energy resolution.

Both man‐made locomotive devices and molecular motors use gears to transform a reciprocating motion into a directed one. One of the most common gears is a rectifier, a mechanically irreversible appliance. The maximal energetic efficiency of an isothermic gear is bounded by unity, as a consequence of the Second Law. However, approaching this ideal efficiency does not imply approaching reversibility. We discuss what properties of a rectifier mostly influence the transduction efficiency and show that an appliance which locks under backward force is just the one which can approach the ideal efficiency either in the reversible or in the irreversible regime.

It has been studied whether the junction connecting the metallic (9,0) zigzag tube and the semiconducting (8,0) zigzag tube shows rectification based on the tight binding model, Hartree-Fock approximation and the Green’s function method. The junction with considered parameters becomes a backward diode.

Periodic structures that lack reflection symmetry act—when periodically rocked by external forces—as rectifiers for Brownian motion. Here we investigate the role of a global coupling (of the ‘Kuramoto-type’) among such rectifiers. We demonstrate that the coupling strength K acts as a control on the sign (it yields a realization for current reversal) and the magnitude of the directed average velocity of Brownian particles. Moreover, raising the coupling strength K, results in an effective reduction of ambient noise. This intriguing effect is revealed in a striking manner for the mean velocity vs. load characteristics.

We show how, via resonant tunneling, a tight binding model of a molecular adsorbate might be used to account for the anomalous conductance observed in STM images of many molecular adsorbates. New calculations show that even strong binding to the substrate does not necessarily destroy a resonance. Electrochemistry can be used to make biomolecular adsorbates that can be imaged by STM reliably. Current‐distance and current‐voltage data obtained over DNA‐salt complexes in suit show that the charge transport is most likely by tunneling and that the electronic properties of the tunnel gap are very different over a molecular adsorbate when compared with a gap that contains just small inorganic contaminants. In particular, conductance over the organic adsorbate is greatly enhanced. The electronic properties of the adsorbate are strongly affected by the position of the STM tip, demonstrating that electronic states might be altered by the stress applied by the STM tip under the control of the STM servo. This provides a mechanism to bring about a resonance or to bring a state close enough to resonance so that the set‐point tunnel conductance is achieved.