Electric Field-induced switching among multiple conductance pathways in single-molecule junctions

Here, we report the switching among multiple conductance pathways achieved by sliding the scanning tunneling microscope tip among different binding sites under different electric fields. With the electric field increase,...

Carrier Transport Properties of GAN in High Electric Field

The Monte Carlo (MC) simulation of the carrier transport mechanisms including impact ionization at high electric field in GaN is presented. Two non-parabolic conduction and valence bands were considered for the simulation of transport properties of electron and hole respectively. The carriers’ drift velocity and energy are simulated as a function of applied electric field at room temperature. The maximum velocity of electron is 2.85 × 107 cm/s at 140 kV/cm. The velocity of electron is saturated at 2 × 107 cm/s at electric field greater than 300 kV/cm. In our work, the velocity of hole is 5 × 106 cm/s at 500 kV/cm. Electron energy increases as the electric field increase and fluctuated at electric field greater than 600 kV/cm when impact ionization occurred. The impact ionization rates are obtained by using modified Keldysh equation. The hole impact ionization rate is higher than that of electron. This work also shows higher electron impact ionization coefficient than that of hole at electric field greater than 4.04 MV/cm

The Electrical Behaviour of Polymer Insulator under Different Weather Conditions

This paper presents the behavior of 33kV polymer insulator under nominal voltage and impulse by means of lightning activities. The electrical performance of the insulator is translated to electric field under uniform weather conditions which comprises of air humidity and contamination. ANSYS Maxwell modeling software is used to simulate the structure of the polymer insulator based on the real existing insulator’s dimension. The trend of electric field increase is discussed in detail.

Ferroelectric and Photovoltaic Properties of Mn-Doped Bismuth Ferrite Thin Films

Bismuth ferrite is an important material in ferroelectric photovoltaic field, because of its narrow band gap and large polarization. Doping is a common method to further improve the photovoltaic properties of bismuth ferrite. Mn-doped bismuth ferrite thin films were prepared by sol-gel method. The effects of manganese on the crystal structure, ferroelectric and photovoltaic properties have been investigated. The result indicates that Mn-doped bismuth ferrite thin films are single phase and the lattice constant increases with the increase of manganese content. As manganese content increases, the remnant polarization and coercive electric field increase, while the short circuit photocurrent density and power conversion efficiency decrease. The open circuit photovoltage increases first and reaches the maximum and then decreases as manganese content increases. The results indicate that enhanced ferroelectricity caused by addition of manganese doesn’t make improvement on the photovoltaic characteristic.

The Charge-Discharge Properties of the Non-Linear Dielectric Capacitor

The Charge-discharge Properties of Two Different Non-liner Dielectric Capacitors which Were Made by the La-modified PZST Anti-ferroelectric Ceramics (AFE) Capacitors Were Investigated by Measuring the Hysteresis Loops, None-load Discharge Current-time Curves under Different Charge Voltage, and with 100ohm Discharge Current-time Curve. through Compared these Properties with the Liner Capacitors, it Is Evidence to Summarize the No-liner Properties of the AFE Ceramics. it Was Found that, the AFE Capacitors Imax Is Increasing in No-linear with the Charge Electric Field Increase, but to the Linear Capacitor, the Imax-E Curves is a Beeline. and the AFE Imax-E Curve is Similar to the P-E Curve, and this Paper Explained these.

PROPERTIES OF RESONANCE TRANSMISSION THROUGH A SEMICONDUCTOR DOUBLE-WELL STRUCTURE WITH SPIN-ORBIT COUPLING

In this paper, we investigate effects of the Dresselhaus spin-orbit coupling, inter-well coupling, and external bias on the dynamics of resonance tunneling through a semiconductor double-well structure. Based on the transfer matrix technique and the single band effective-mass approximation method, the numerical results demonstrate that the transmission peaks of the spin-up and spin-down electrons split due to the Dresselhaus spin-orbit coupling in the double-well structure. As the in-plane wave vector and external electric field increase, the split becomes farther apart. There is a prominent difference between the lifetime of the quasibound energy level for different spin-polarized electrons. The spin-dependent tunneling time is obtained using the time-dependent Schrödinger equation.

Derivation of inner magnetospheric electric field (UNH-IMEF) model using Cluster data set

We derive an inner magnetospheric electric field (UNH-IMEF) model at L=2–10 using primarily Cluster electric field data for more than 5 years between February 2001 and October 2006. This electric field data set is divided into several ranges of the interplanetary electric field (IEF) values measured by ACE. As ring current simulations which require electric field as an input parameter are often performed at L=2–6.6, we have included statistical results from ground radars and low altitude satellites inside the perigee of Cluster in our data set (L~4). Electric potential patterns are derived from the average electric fields by solving an inverse problem. The electric potential pattern for small IEF values is probably affected by the ionospheric dynamo. The magnitudes of the electric field increase around the evening local time as IEF increases, presumably due to the sub-auroral polarization stream (SAPS). Another region with enhanced electric fields during large IEF periods is located around 9 MLT at L>8, which is possibly related to solar wind-magnetosphere coupling. Our potential patterns are consistent with those derived from self-consistent simulations. As the potential patterns can be interpolated/extrapolated to any discrete IEF value within measured ranges, we thus derive an empirical electric potential model. The performance of the model is evaluated by comparing the electric field derived from the model with original one measured by Cluster and mapped to the equator. The model is open to the public through our website.

Two-dimensional simulation of initiation and evolution of a plasma channel in the XeCl laser pumping discharge

We present two-dimensional simulation results of the formation and evolution of a diffuse plasma channel in the XeCl pumping discharge. Channel formation was initiated by metallic convexity at the cathode surface with a characteristic dimension of ∼0.1 cm. Two pumping regimes were considered. Initial voltage in the second regime was increased 1.6 times and impedance was decreased 2 times in contrast with the first regime. Evolutions and spatial distributions are presented for electron density, electric field, and frequencies of the main process. In the first regime, the diffuse plasma channel forms. The main processes causing development of the plasma channel are inhomogeneous distribution of the electric field, increase of the stepwise ionization frequency at ne ∼ 1015 cm−3, and depletion of HCl. Increasing of the initial voltage and decreasing of the impedance in the second regime results in a quick rise of the discharge current and electron density in the discharge gap, and uniform discharge takes place during the current pulse.