Parameters Of Potential Barrier Research Articles

ОДНОМЕРНАЯ ДИНАМИКА ДОМЕННОЙ ГРАНИЦЫ В СЕМИСЛОЙНОЙ ФЕРРОМАГНИТНОЙ СТРУКТУРЕ

The dynamics of the domain boundary is considered using the example of a seven-layer ferromagnetic structure with three thin and four wide magnetic layers. The structure of the domain boundary is represented as a kink solution of the sine-Gordon equation. The equation of motion for magnetization was solved numerically using an explicit scheme. The discretization of the equation was carried out according to a standard five-point scheme of the "cross" type. The paper shows the features of the dynamics of the domain boundary in a multilayer magnetic system in the presence of thin magnetic layers with an increased value of the magnetic anisotropy constant. Thin layers with an increased value of the magnetic anisotropy constant compared to the homogeneous state represent potential barriers to the moving domain boundary. Thin layers with an increased magnitude of magnetic anisotropy compared to a homogeneous state represent potential barriers to a moving domain boundary. A diagram of possible scenarios of the dynamics of the domain boundary is constructed depending on the initial velocity of its movement and the distance between three thin magnetic layers. The maximum value of the kink velocity for reflection from all potential barriers, depending on their size, is obtained. With an increase in the height and width of the barrier, the value of such a threshold maximum reflection velocity of the domain boundary increases nonlinearly. With a sufficiently high barrier height, there is already an almost linear dependence on the width of this threshold velocity. With a slight increase in the speed of movement of the domain boundary, the kink can pass through the first barrier, but it is reflected from the second barrier. There is also a case of kink oscillation between the second and third potential barriers. Such fluctuations are clearly inharmonious. The dependence of the threshold velocity on the distance between the barriers is obtained. As the distance between the barriers increases, the threshold speed value tends to a value equal to the threshold speed for one barrier. In the work, the minimum value of the speed of the domain boundary of the passage of all layers, depending on the parameters of potential barriers, is obtained. It is also found that there is a critical distance separating the dynamics of the domain boundary into two regions with qualitatively different behavior of the system.

Photosensitivity of Nanostructured Schottky Barriers Based on GaP for Solar Energy Applications

This work investigates the surface-barrier photoelectric properties of Au-palladium-n-GaP structures. Research into the visible spectrum region, under the action of both linearly polarized and natural radiation, provides us with new information about the height of the barrier, the interface m-s section, and the GaP band structure. SBs based on GaP (p- and n-type) are helpful for researchers in developing advantageous structures for creating various photovoltaic devices—photodetectors for fiber-optic control of energy systems or possible structures for solar energy. Despite many years of research, issues concerning the band structure of semiconductors based on the phenomenon of photoelectroactive absorption in such surface-barrier structures’ m-s remain urgent in the creation of new high-performance devices. Such structures may also be interesting for creating solar energy systems. They create a thin insulating dielectric layer (usually an oxide layer) in solar cells on SBs between the m and the semiconductor substrate. The advantage of solar cells based on m dielectric semiconductor structures is the strong electric field near the surface of the semiconductor that usually has a direction favoring the collection of carriers created by short-wavelength light. Diffusion of impurities usually results in crystal defects in the active region. There are no such defects in the studied elements. This is also the difference between solar cells on m dielectric structures and elements with diffusion in p-n junctions. We studied the PS of Au-Pd-n-GaP nanostructures to determine the height of the potential barrier qφBo and obtained accurate data on the zone structure of the n-GaP. The PS of nanostructured Au-Pd-n-GaP structures was studied in the visible region of the spectrum. Essential information about the semiconductor’s potential barrier parameters and band structure was obtained. The intermediate Pd nanolayer between Au and GaP has specific effects on the Au-Pd-n-GaP nanostructure, which are of considerable practical and scientific significance for future needs.

The role of SiO2 in semiconducting BaTiO3-based ceramics: Extension of the Jonker model and effect on the electrical properties

BaTiO3-based ceramics with positive temperature coefficient of resistance (PTCR) recently gained in significance due to their application as cabin heaters in electrical vehicles. Although used as a sintering aid in BaTiO3 ceramics for decades, the effect of SiO2 on the electrical properties as well as the underlying physical mechanisms have not been investigated in detail. Here, we systematically study the influence of SiO2 on PTCR properties, but also on the resistance development at temperatures below the PTC regime, which has hardly been given attention to so far. Using capacitance-voltage measurements, we determine temperature dependent grain boundary potential barrier parameters. By combining these results with x-ray diffraction measurements and resistance-temperature properties, we propose a model describing the resistance evolution throughout the whole temperature range from room-temperature up to the PTCR regime. Further, we show that electrical field strength increases with higher SiO2 content, accompanied by a reduced voltage sensitivity of resistance.

Calculation of the grain potential barrier in the poly− and nanocrystalline semiconductors

The distribution of potential and parameters of potential barrier in semiconductor crystallite was calculated numerically. The calculation was carried out in spherical crystallite with evenly distributed donors and surface states. The calculation assumed that the surface charge is screened by both ionized donors and free electrons, the contribution of which cannot be neglected in semiconductors with high concentration of free electrons. The height of potential barrier is shown to nonmonotonically depend on the concentration of donors. The dependence of height of potential barrier on the concentration of donors may be divided into two part. One part of dependence describes the fully depleted crystallite and the second part describes the party depleted crystallite. On the first part the height of potential barrier increases with the donor concentration but on the second part the height of potential barrier decreases. The height of the potential barrier increases with increasing of concentration of surface states. The possibility of existing of potential barriers is estimated in nano− and polycrystalline metal oxide semiconductors used as sensitive layers of gas sensors. It is concluded that if the radius of crystal grains in metal oxide semiconductors does not exceed 10 nm, the explanation of the sensitivity of the sensor to gas by using a commonly barrier model seems unlikely. It is demonstrated that shape of crystallite and the contribution of free electrons to screening of surface charge have to be taken into account to calculation of width of potential barrier.

Tunneling Current in Oppositely Connected Schottky Diodes Formed by Contacts between Degenerate n-GaN and a Metal

The nonlinear behavior of the I–V characteristics of symmetric contacts between a metal and degenerate n-GaN, which form oppositely connected Schottky diodes, is investigated at free-carrier densities from 1.5 × 1019 to 2.0 × 1020 cm–3 in GaN. It is demonstrated that, at an electron density of 2.0 × 1020 cm–3, the conductivity between metal (chromium) and GaN is implemented via electron tunneling and the resistivity of the Cr–GaN contact is 0.05 Ω mm. A method for determining the parameters of potential barriers from the I–V characteristics of symmetric opposite contacts is developed. The effect of pronounced nonuniformity of the current density and voltage distributions over the contact area at low contact resistivity is taken into account. The potential-barrier height for Cr–n+-GaN contacts is found to be 0.47 ± 0.04 eV.

Туннельный ток во встречных диодах Шоттки, образованных контактами между вырожденным GaN n-типа и металлом

AbstractThe nonlinear behavior of the I – V characteristics of symmetric contacts between a metal and degenerate n -GaN, which form oppositely connected Schottky diodes, is investigated at free-carrier densities from 1.5 × 10^19 to 2.0 × 10^20 cm^–3 in GaN. It is demonstrated that, at an electron density of 2.0 × 10^20 cm^–3, the conductivity between metal (chromium) and GaN is implemented via electron tunneling and the resistivity of the Cr–GaN contact is 0.05 Ω mm. A method for determining the parameters of potential barriers from the I – V characteristics of symmetric opposite contacts is developed. The effect of pronounced nonuniformity of the current density and voltage distributions over the contact area at low contact resistivity is taken into account. The potential-barrier height for Cr– n ^+-GaN contacts is found to be 0.47 ± 0.04 eV.

Fluorinated graphene films with graphene quantum dots for electronic applications

This work analyzes carrier transport, the relaxation of non-equilibrium charge, and the electronic structure of fluorinated graphene (FG) films with graphene quantum dots (GQDs). The FG films with GQDs were fabricated by means of chemical functionalization in an aqueous solution of hydrofluoric acid. High fluctuations of potential relief inside the FG barriers have been detected in the range of up to 200 mV. A phenomenological expression that describes the dependence of the time of non-equilibrium charge emission from GQDs on quantum confinement levels and film thickness (potential barrier parameters between GQDs) is suggested. An increase in the degree of functionalization leads to a decrease in GQD size, the removal of the GQD effect on carrier transport, and the relaxation of non-equilibrium charge. The study of the electronic properties of FG films with GQDs has revealed a unipolar resistive switching effect in the films with a relatively high degree of fluorination and a high current modulation (up to ON/OFF ∼ 104–105) in transistor-like structures with a lower degree of fluorination. 2D films with GQDs are believed to have considerable potential for various electronic applications (nonvolatile memory, 2D connections with optical control and logic elements).

Investigation on effects of stochastic resonance potential barrier parameters on tastant perception abilities of taste cell-based sensor

Investigation on effects of stochastic resonance potential barrier parameters on tastant perception abilities of taste cell-based sensor

Evaluation of surface potential barriers after activation of GaAs photocathode

According to the ratios of the peak-values of photocurrents arising separately during the single Cs activation and during the Cs-O activation for negative electron affinity(NEA) GaAs photocathode, and the theoretical energy distributions of the photoelectrons passing separately through the single and the double potential barriers, a new method of evaluating the surface potential barrier parameters of NEA GaAs photocathode is presented. The results obtained by this method accord well with the double-dipole model theory and are in agreement with the results by fitting the experimental electrons energy distribution curve. The method is simple and efficave, which enriches the approaches to the evaluation of activation effect and surface characteristic of NEA GaAs photocathodes without increasing other test means.

Coherent quantum dynamics of mesoscopic metallic ring with a barrier

In this paper we consider a mesoscopic 1D, ballistic, metallic ring with a potential barrier. We show that the coherent coupling between two distinct quantum states with different winding numbers can lead to a formation of a qubit. We discuss the possible realizations of such a ring, the adjustment of a potential barrier parameters and the possible decoherence sources.

Effect of electric fields on the transmission of a double heterostructure based on GaN with a quantum well

The potential-barrier parameters (heights) of the AlGaN/InGaN/GaN structure are determined, and the temperature dependences of these parameters are considered. Using the parameters, the transmission coefficient of the structure is calculated both with allowance for the external and internal fields and with no allowance for the electric field. The quantum-well energy levels are determined using the transmission coefficient; the shift of the transmission-coefficient maxima under the action of external bias voltage is explained.

Electrical characteristics and the energy band diagram of the isotype n-Si1−x Gex/n-Si heterojunction in relaxed structures

The electrical characteristics of the relaxed isotype n-Si1−xGex/n-Si heterojunction are studied for the case of a misfit-dislocation network formed in the vicinity of the heterointerface. The data obtained are used to analyze the energy bands of the heterostructure. The band structure of the crystal near the interface is shown to be formed by a charge at lattice defects. The potential-barrier parameters are estimated by analyzing the temperature dependences of the J-U and C-U characteristics of the system.

Near-electrode model of transient currents in (Ba,Sr)TiO3 thin film capacitor structures

Transient currents in SrRuO3//Ba0.8Sr0.2TiO3//SrRuO3 thin film capacitors, in the time interval 0.05–2.5 s after the step voltage switching on and off, have been investigated. The origin of these currents is proposed, including two components: charging (discharging) of near-electrode potential barriers and oxygen vacancy migration. It has been established that transient current of capacitor charging is mainly determined by the barrier component, and transient current of capacitor discharging is due to both components. The parameters of potential barriers were determined giving a good agreement of the calculated time dependences of transient currents with the experimental data.

Temperature dependence of cryochemical H-tunneling reactions

The temperature dependence of tunneling transition of the atomic particle in solids is studied near absolute zero. The different mechanisms of the temperature dependence are considered. They are the medium reorganization, the potential barrier parameters modulation, and the under-barrier friction The nonadiabatic effects are also considered. The rate constant K is described by formula ln K=ln K0+C4T4+C5T5+C6T6+C8T8 at low temperatures. It was conducted through the comparison of theory with the experimental data from the article of Kumada et al. [Chem. Phys. Lett. 261, 463 (1996)]. It turned out that good agreement takes place if one takes into account the quantum properties of the hydrogen crystal with the assumption of the dominated role of medium reorganization.

Conductivity relaxation in coated porous silicon after annealing

A study has been carried out of the effect of a brief anneal at 450–550 °C on the conductivity of porous silicon coated with a metallic film. Porous silicon, formed on p-and n-type substrates, had porosities of 16–40% and 5–10%, respectively. It has been shown that for anneals at 500 and 550 °C porous silicon on p-type Si is converted to the highly conducting state. The conductivity relaxation in coated porous silicon layers on p-Si after annealing is described. The results are analyzed from the point of view of a model of passivation of the impurity atoms by hydrogen. It is shown that after annealing an aluminum-〈porous silicon〉 junction possesses a rectifying property. The potential barrier parameters for Al-〈porous silicon〉 junctions on p-and n-type substrates are determined.

The torsional Raman spectra of C2H6 and C2D6

The torsional Raman spectra of C2H6 and C2D6 have been experimentally investigated with an improved conventional Raman spectrometer. Wave numbers and absolute cross sections of all observed bands have been satisfactorily interpreted within the experimental accuracy by means of a simple, pure-torsional Hamiltonian and a model for the torsional dependence of the molecular polarizability. The effective threefold potential barrier parameters for C2H6 have been taken from the recent literature, whilst for C2D6 the values V3eff (C2D6)=990±2 cm−1 and V6eff (C2D6)=7.9±1 cm−1 were obtained.

On rephasing mechanisms of quantum wave packets

Mechanisms for shrinking of spreading wave packets are investigated. Special attention is devoted to the process of reflection. Simple formulae are given for the rephasing parameters of potential barriers and wells. A thought experiment of observing the rephasing of a single wave packet is discussed.

Solitonic proton transport in model hydrogen-bonded chains

Dynamics of proton motion in the discrete one-dimensional hydrogen-bonded chain have been analysed by numerical integration of equations of motion. The role of the asymmetric potential barrier parameters is considered within the solitonic model of the proton transfer.

New method of determining the potential barrier parameters of thin film MIM structures

New method of determining the potential barrier parameters of thin film MIM structures

Vibrational spectra and torsional barriers for multitop molecules: Trimethylarsine, trimethylarsine oxide and trimethylarsine sulfide

Raman spectra are presented for liquid (CH 3) 3As and sublimed films of (CH 3) 3As, (CH 3) 3AsO and (CH 3) 3AsS. Far i.r. spectra are also shown for (CH 3) 3As and (CD 3) 3As and vibrational assignments are offered for all compounds. From spectra of the low temperature films, and by means of isotopic substitution, the A 2 and E torsional frequencies have been identified for most compounds. Potential barrier parameters are calculated for several common models and it is found that an analysis which includes mixing between the E torsion and skeletal bending coordinates is desirable if accurate barriers (better than ∼10%) are sought. Methyl top—top interaction terms are even more sensitive to the potential model used. Barrier values of 820, 1130 and 920 cm −1 are obtained for (CH 3) 3As, (CH 3) 3AsO and (CH 3) 3AsS respectively while the corresponding top—top coupling terms are −91 and −206 cm −1 for (CH 3) 3As and (CH 3) 3AsO. These values are summarized with results for other C 3ν, multi-top molecules and all are discussed in terms of non-bonded interactions between methyl hydrogens and the other atoms in the molecules.