Low Electric Field Conditions Research Articles

Bounce and contact mode regimes for drop impact on smooth surfaces: The influence of gas kinetics and electrostatics

When liquid drops impact on solid surfaces, an air layer forms in between the drop and the surface, acting as a cushion to mitigate the impact. In this work, we focus on delineating the bounce and contact mode regimes of impacting drops on smooth surfaces, specifically discerning whether drops rebound from the air layer or make contact with the solid surfaces, and pinpointing the precise contact modes between the drop and solid surfaces by resolving the gas film evolution and rupture. Our simulation model incorporates gas kinetics and electrostatics effects, both of which have been validated by experiments documented in the literature or theoretical models regarding thin film instabilities. We undertake a comprehensive review and categorization of the contact modes and elucidate how they change under different conditions of impact velocities, ambient pressures, and electric field intensities. We also provide some perspectives on the regime map for the lubricated surfaces, which contains an unresolved issue that the critical Weber number for bouncing-wetting transition is significantly reduced compared to the solid smooth surfaces like mica. These insights have noteworthy practical implications offering guidance for a wide range of scenarios, from normal-pressure environments to low-pressure conditions at high altitudes, encompassing high electric field conditions such as nanogenerators as well as low electric field conditions resembling glass surfaces with static electricity.

First-Principles Modeling of Preferential Solvation in Mixed-Modifier Differential Mobility Spectrometry.

Differential mobility spectrometry (DMS) separates ions based on mobility differences between high and low electric field conditions. To enhance resolution, solvents such as water and acetonitrile are often used to modify the collision environment and take advantage of differing dynamic clustering behavior between analytes that coelute in hard-sphere environments (e.g., N2). When binary solvent mixtures are used to modify the DMS environment, one solvent can have a dominant influence over the other with respect to ion trajectories. For example, for quinoline derivatives, a 9:1 water:acetonitrile solvent mixture exhibited identical behavior to an environment containing only acetonitrile as a modifier. It was hypothesized that this effect arises due to the significantly different binding strengths of the two solvents. Here, we utilize a first-principles model of DMS to study analytes in single and binary solvent mixtures and explore the effects governing the dominance of one solvent over the other. Computed DMS dispersion curves of quinoline derivatives are in excellent agreement with those measured experimentally. For mixed-modifier environments, the predicted cluster populations show a clear preferential solvation of ions with the stronger binding solvent. The influence of ion-solvent binding energies, solvent concentration, and solvent molecule size is discussed in the context of the observed DMS behavior. This work can guide the usage of binary solvent mixtures for improving ion separations in cases where compounds coelute in pure N2 and in single-solvent modifier environments. Moreover, our results indicate that binary solvent mixtures can be used to create a relative scale for solvent binding energies.

Remarkably enhanced dielectric stability and energy storage properties in BNT\u2014BST relaxor ceramics by A-site defect engineering for pulsed power applications

Lead-free bulk ceramics for advanced pulsed power capacitors show relatively low recoverable energy storage density (Wrec) especially at low electric field condition. To address this challenge, we propose an A-site defect engineering to optimize the electric polarization behavior by disrupting the orderly arrangement of A-site ions, in which {rm{B}}{{rm{a}}_{0.105}}{rm{N}}{{rm{a}}_{0.325}}{rm{S}}{{rm{r}}_{0.245 - 1.5x}}{_{0.5x}}{rm{B}}{{rm{i}}_{0.325 + x}}{rm{Ti}}{{rm{O}}_3} ({rm{BN}}{{rm{S}}_{0.245 - 1.5x}}{_{0.5x}}{{rm{B}}_{0.325 + x}}{rm{T}}, x = 0, 0.02, 0.04, 0.06, and 0.08) lead-free ceramics are selected as the representative. The {rm{BN}}{{rm{S}}_{0.245 - 1.5x}}{_{0.5x}}{{rm{B}}_{0.325 + x}}{rm{T}} ceramics are prepared by using pressureless solid-state sintering and achieve large Wrec (1.8 J/cm3) at a low electric field (@110 kV/cm) when x = 0.06. The value of 1.8 J/cm3 is super high as compared to all other Wrec in lead-free bulk ceramics under a relatively low electric field (< 160 kV/cm). Furthermore, a high dielectric constant of 2930 within 15% fluctuation in a wide temperature range of 40–350 °C is also obtained in {rm{BN}}{{rm{S}}_{0.245 - 1.5x}}{_{0.5x}}{{rm{B}}_{0.325 + x}}{rm{T}} (x = 0.06) ceramics. The excellent performances can be attributed to the A-site defect engineering, which can reduce remnant polarization (Pr) and improve the thermal evolution of polar nanoregions (PNRs). This work confirms that the {rm{BN}}{{rm{S}}_{0.245 - 1.5x}}{_{0.5x}}{{rm{B}}_{0.325 + x}}{rm{T}} (x = 0.06) ceramics are desirable for advanced pulsed power capacitors, and will push the development of a series of Bi0.5Na0.5TiO3 (BNT)-based ceramics with high Wrec and high-temperature stability.

Multichannel Depletion-Type Field-Effect Transistor Based on Ferromagnetic Germanene

Based on ferromagnetic germanene, we theoretically propose a multichannel depletion-type field-effect transistor (FET) operated by a vertical electric field. The electron transport properties of the topological transistor are investigated through the nonequilibrium Green's function method. The results reveal that new edge channels can be formed by removing some $\mathrm{Ge}$ atoms along the $x$ axis of the device. The proposed multichannel ferromagnetic germanene transistor has a twice on-state current and half subthreshold swing than that of traditional germanene FETs. Under the coaction of electric induced staggered potential and staggered exchange field, both the $100\mathrm{%}$ spin-polarized edge states and valleys can be achieved. The ferromagnetic germanene FET can be turned off just by adjusting the electric field. In the low electric field conditions, the switching-off mechanism is due to spin blocking caused by the edge-state mismatch, while for relatively high electric field cases, both the edge-state mismatch and energy-valley mismatch are utilized. With the moderate increase in the exchange field, the switching mechanism is not changed, but the threshold electric field and breakdown voltage of the FET can be, respectively, reduced and enhanced significantly. All the results indicate that the proposed ferromagnetic germanene FET is a promising candidate for ultra-low-power dissipation topological devices.

Atom probe tomography quantification of carbon in silicon

Atom Probe Tomography (APT) was used to quantify carbon in implanted silicon at two various electric fields (~ 15 and 20 V/nm). Using equal proportions of implanted 12C and 13C, the numerous molecular ions that were observed were identified and their contribution to the carbon content statistically derived. Much more accurate carbon quantification was obtained in the lowest electric field analysis by comparing APT with Secondary Ion Mass Spectroscopy profiles. This was assigned to a lower amount of molecular ion dissociations. Furthermore, the number of self-interstitials trapped per carbon atom in clusters was derived. This value of interest for the microelectronics industry regarding dopant diffusion and implantation induced defects was estimated close to one, in agreement with the expected stoichiometry of the SiC phase present in the phase diagram. However, this was obtained only when using low electric field conditions.

Memristive and magnetoresistance effects of SnSe&lt;sub&gt;2&lt;/sub&gt;

Memristor and magnetoresistance (MR) are widely used in the field of information storage. In recent years, SnSe&lt;sub&gt;2&lt;/sub&gt;, as an information storage material with both memristor and MR effects, has received a lot of attention of the researchers. It is of great significance to further explore its electrical transport mechanism. In this paper, the high-purity bulk SnSe&lt;sub&gt;2&lt;/sub&gt; samples are prepared by melting method together with spark plasma sintering. The &lt;i&gt;V&lt;/i&gt;-&lt;i&gt;I&lt;/i&gt; curves are measured under different temperatures and magnetic fields. The memristive and MR effect of SnSe&lt;sub&gt;2&lt;/sub&gt; are systematically investigated. After the memristive characteristics are excluded from interfacial junction effect, phase transition and conductive wire channels, the memristive effect at different temperatures is attributed to the space charge limiting current effect under defect control. Under low electric field conditions, the internal carrier concentration of material is much higher than the injected carrier concentration and the &lt;i&gt;V&lt;/i&gt;-&lt;i&gt;I&lt;/i&gt; curve obeys ohmic conduction. When the voltage increases to the switching voltage &lt;i&gt;V&lt;/i&gt;&lt;sub&gt;on&lt;/sub&gt;, the internal defects of the material are filled with the injected carriers as the transport time of the injected carrier is less than the dielectric relaxation time, and the &lt;i&gt;V&lt;/i&gt;-&lt;i&gt;I&lt;/i&gt; curves deviate from ohmic conductivity. When the voltage reaches the transition voltage &lt;i&gt;V&lt;/i&gt;&lt;sub&gt;TFL&lt;/sub&gt;, the injected carrier increases exponentially, and the &lt;i&gt;V&lt;/i&gt;-&lt;i&gt;I&lt;/i&gt; curve presents negative differential phenomenon. Finally, the space charge inside the material will limit the further injection of external carriers, and the &lt;i&gt;V&lt;/i&gt;-&lt;i&gt;I&lt;/i&gt; curve follows the Child law. As the temperature decreases to 10 K, the memristive phenomenon weakens because a large number of defects for accepting the injected carriers are reduced due to the decrease of impurity ionization at low temperatures. At the same time, the sample exhibits a large negative MR at 10 K and 100 K. When impurity scattering predominates, the electrons will be subjected to multiple scattering by the impurities, resulting in localization of carriers. The negative MR effect is related to the inhibition of the carrier localization by the magnetic field. In our work, a large negative MR of about –37% at 0.6 T and 10 K are obtained, which is likely to originate from the disordered distribution of Se vacancy in the material. With the increase of temperature, the scattering mechanism gradually evolves from the impurity scattering into the lattice scattering, and the negative MR effect gradually develops into the positive MR effect.

Ab initio calculation of electron–phonon coupling in monoclinic β-Ga2O3 crystal

The interaction between electrons and vibrational modes in monoclinic β-Ga2O3 is theoretically investigated using ab-initio calculations. The large primitive cell of β-Ga2O3 gives rise to 30 phonon modes all of which are taken into account in transport calculation. The electron-phonon interaction is calculated under density functional perturbation theory and then interpolated using Wannier–Fourier interpolation. The long-range interaction elements between electrons and polar optical phonon (POP) modes are calculated separately using the Born effective charge tensor. The direction dependence of the long-range POP coupling in a monoclinic crystal is explored and is included in the transport calculations. Scattering rate calculations are done using the Fermi golden rule followed by solving the Boltzmann transport equation using the Rode's method to estimate low field mobility. A room temperature mobility of 115 cm2/V s is observed. Comparison with recent experimentally reported mobility is done for a wide range of temperatures (30 K–650 K). It is also found that the POP interaction dominates the electron mobility under low electric field conditions. The relative contribution of the different POP modes is analyzed and the mode 21 meV POP is found to have the highest impact on low field electron mobility at room temperature.

Interpretation of Polar Orders Based on Electric Characterizations: Example of Pb(Yb $$_{1/2}$$ 1 / 2 Nb $$_{1/2}$$ 1 / 2 )O $$_3$$ 3 -PbTiO $$_3$$ 3 Solid Solution

Characterizing the polar order is a fundamental step in the understanding of a material and a necessity for application purposes since each polar order is associated with specific functionalities. Here, using the Pb(Yb\(_{1/2}\)Nb\(_{1/2}\))O\(_3\)-PbTiO\(_3\) (PYN-PT) solid solution as an example, we propose to differentiate the polar order based on two simple electrical characterization methods: measurement of the dielectric constant and hysteresis loops. Comparing the dielectric constant measured in high and low electric field conditions, we show that the polarization-electric field measurements may induce out-of-equilibrium phases. The better understanding of the effect of the measuring conditions on the polar order has led us to propose a new sequence of equilibrium polar orders in the PYN-PT solid solution at room temperature.

Performance Enhancement of Metal Floating Gate Memory by Using a Bandgap Engineered High-k Tunneling Barrier

With conventional nonvolatile flash memories approaching their scaling limit from cell-to-cell coupling and stress induced leakage current, many studies have been performed to explore the next generation memory technologies. Metal floating gate (FG) memory is one of the most promising candidates because of its less ballistic transport even with ultrathin floating gate (<10 nm). Enhancd memory performance including fast program speed, excellent data retention and program/erase (P/E) cycling endurance have been repored by P. Blomme et. al from IMEC. Moreover, S. Jayanti et. al explored that full Metal-FG could scaled down to even 1 nm thickness with excellent memory performance. Nevertheless, less attention had been paid on the study of tunneling layer which matches with full Metal-FG. Sufficient gate coupling ratio could obtained by using tunneling barrier without compromising the device performance. In our previous work , both the P/E speed and retention characteristic has been improved in the TaN floating gate flash memory based on the SiO2/HfO2 dual tunneling layer structure.The HfO2 layer adjacent to TaN was expected to suppress the inter-diffusion between tunneling dielectric and TaN FG. In this letter, bandgap engineered of the triple tunneling layer (SiO2/HfO2/Al2O3) has been demonstrated to be an effective method to optimize the performance of TaN Metal-FG. Compared to a device with a single SiO2 tunneling layer, faster program/erase speed and better data retention characteristics have been simultaneously achieved in this proposed structure. The schematic structure of a metal floating gate device is illustrated in Figure 1. P-type Si (100) wafers were cleaned by the standard Radio Corporation of America process. Devices with SiO2 (SiO2-4.5nm), SiO2/HfO2 (SiO2-2.7nm/HfO2-8nm) and SiO2/HfO2/Al2O3 (SiO2-2.7nm/HfO2-4nm/Al2O3-2nm) as tunneling layers are denoted as O-TaN , OH-TaN and OHA-TaN respectively. The thicknesses of tunneling layers were chosen for achieving the same effective oxide thickness (EOT). The memory characteristics such as operation speed and data retention were measured by using Agilent B1500A. The C-V hysteresis memory window of both O-TaN and OH-TaN device have been test. The improvement in the memory window for the OH-TaN device indicates the better carrier trapping capability of the stacked SiO2/HfO2 structure.It also can be attributed to the difference of the effective tunneling distance, which is resulted from the different potential drop when low-k and high-k dielectrics are employed as tunneling layer. Devices with SiO2/HfO2/Al2O3 (OHA) as tunneling layer was further characterized and compared with O-TaN and OH-TaN device. Compared to the O-TaN device, fast P/E speed along with large memory window is achieved with the OH-TaN and OHA-TaN device. Moreover, the device with OHA is slightly more advanced than the device with OH. The improvement of P/E speed in the OH-TaN and OHA-TaN structure can be explained by the energy band diagram under the program bias condition. Owing to the difference of voltage drop and bandgap between SiO2 and high-k (HfO2 and Al2O3), the effective tunneling distance is reduced in a high-k engineered tunneling layer structure. In addition, The reason that devices with OHA as tunneling layer shows slightly faster P/E speed than devices with OH as tunneling layer may attribute to a high defect state density at the interface of HfO2 and Al2O3. We also programmed the devices with an identical initial flat-band voltage to compare their room temperature retention characteristics. The OH-TaN and OHA-TaN structure exhibits negligible decrease in flatband voltage, whereas the control sample shows a significant loss of 2.7 V in flatband voltage in 104s. This can be attributed to the larger physical tunneling layer thicknesses of the engineered ones. The tunneling can be suppressed by large physical thickness under flat band or low electric field conditions. In this paper, a stacked high-k tunneling layer is proposed and investigated for TaN metal floating gate memory application. Compared to a single SiO2 tunneling layer, a stacked SiO2/HfO2 (SiO2-2.7nm/HfO2-8nm) and SiO2/HfO2/Al2O3 (SiO2-2.7nm/HfO2-4nm/Al2O3-2nm) tunneling layer structure have several memory performance improvements: a larger memory window, faster program/erase speed and better data retention characteristics. The improvement of P/E speed in the high-k tunneling barrier structure can be explained by the energy band diagram under the P/E bias condition. the effective tunneling distance is reduced Owing to the difference of voltage drop and bandgap between SiO2 and high-k (HfO2 and Al2O3). The performance enhancement of retention is attributed to the larger physical tunneling layer thicknesses of the high-k engineered ones. This work was supported by the National Natural Science Foundation of China (Grant No. 61306107, No. 61474137, No. 61404168, No. 61404160), China Postdoctoral Science Foundation funded project (No.2014M550866), and the Scientific Research Foundation of CUIT (KYTZ201318, J201404). Figure 1

Application of increased temperature from an exogenous source to enhance gene electrotransfer

The presence of increased temperature for gene electrotransfer has largely been considered negative. Many reports have published on the lack of heat from electrotransfer conditions to demonstrate that their effects are from the electrical pulses and not from a rise in temperature. Our hypothesis was to use low levels of maintained heat from an exogenous source to aid in gene electrotransfer. The goal was to increase gene expression and/or reduce electric field. In our study we evaluated high and low electric field conditions from 90V to 45V which had been preheated to 40°C, 43°C, or 45°C. Control groups of non-heated as well as DNA only were included for comparison in all experiments. Luciferase gene expression, viability, and percent cell distribution were measured. Our results indicated a 2–4 fold increase in gene expression that is temperature and field dependent. In addition levels of gene expression can be increased without significant decreases in cell death and in the case of high electric fields no additional cell death. Finally, in all conditions percent cell distribution was increased from the application of heat. From these results, we conclude that various methods may be employed depending on the end user's desired goals. Electric field can be reduced 20–30% while maintaining or slightly increasing gene expression and increasing viability or overall gene expression and percent cell distribution can be increased with low viability.

Influence of VUV illumination on breakdown mechanics: pre-ionization, direct photoionization, and discharge initiation

A microdischarge (MD) vacuum ultraviolet (VUV) light source is fired onto a N2–NO (99.92 : 0.08%) target gas. The minor gas constituent, NO, was chosen for its ionization potential (9.23 eV) and photoionization cross-section (1.4 × 10−18 cm2) at the wavelength of interest (121.6 nm, 10.2 eV). The result is a plasma generated entirely by volume photoionization in a N2–NO background. Using a very low electric field amplitude, charge carriers are drifted though the photoplasma at picoampere levels, serving as a non-invasive diagnostic. Using a simple one-dimensional fluid approximation for the low electric field condition, theoretical predictions of photoplasma current were found to be in meaningful agreement with experimental data. The impact of direct photoionization and pre-ionization on nanosecond timescale high voltage breakdown yielded two primary observations: (1) a significant reduction in the formative delay time necessary for spark formation, and (2) almost complete elimination of the statistical delay time. Again utilizing one-dimensional fluid approximations, reasonable agreement between experimental and simulated breakdown voltage was observed. Utilizing the same VUV source to illuminate a HV spark gap biased to about 95% self-breakdown voltage revealed that direct volume photoionization alone was insufficient to trigger breakdown of the high voltage gap. However, permitting electrode illumination, the same source was found to be capable of triggering breakdown in the undervoltaged gap, albeit with a large temporal jitter.

Effects of a Weak Magnetic Field on Carrier Transport in a Cryogenic Germanium Detector for Dark Matter Search

A magnetic field of a few gauss produces sizeable effects on carrier trans-port and charge collection in a germanium dark matter detector operated at millikelvin temperatures. The magnitude of the effects is explained by the large values of the velocities imparted to the carriers, even under the low electric field conditions typical for charge collection in these devices (a few 106 cm/s at ∼1 V/cm). Using a suitable experimental setup, effects of the magnetic field on electron and hole transport were investigated separately. A dependence of these effects on the orientation of the field relative to the detector axis is demonstrated, arising in part from magnetic flux conservation through the superconducting (Al) annular electrodes on these devices.

Effect of different low electric field conditions on the dielectric properties of Ehrlich tumor

Studies of low electric fields (LEFs) effects on the permeability of the cell membrane are of great interest in molecular medicine. Electroendocytosis is a novel technique depends on using LEFs to incorporate macromolecules as anticancer drugs or genes into the cells. There are wide debates about the optimum electric conditions for electroendocytosis. In this article, Ehrlich tumor tissues were exposed to different LEFs voltages and frequencies in vitro. Dielectric properties before and after the exposure were determined. The results indicated that the exposed groups have significant high permittivity and conductivity compared to unexposed group, as well as having significant low impedance. The results indicated that dielectric measurements can be used to indicate the efficiency of electroendocytosis that as permittivity and conductivity of cell membranes increase, more molecules can passed into the cells. It was also indicated that, as the pulse amplitude increases, the LEFs influence increases, while changing pulse frequency has no obvious effect on dielectric properties of Ehrlich tumor.

Electronic and photoconductive properties of ultrathin InGaN photodetectors

We report on the compositional dependencies of electron transport and photoconductive properties for ultrathin metal-semiconductor-metal photodetectors based on In-rich InxGa1−xN alloys. For a In0.64Ga0.36N∕GaN structure, the rise time close to the RC constant at low fields has been measured along with a transparency of ∼77% and an absorbance of ∼0.2 at a wavelength of 632nm. The electron density profiles and low-field mobilities for different compositions of InGaN have been calculated by numerically solving the Schrödinger and Poisson equations and applying the ensemble Monte Carlo method, respectively. It was demonstrated that in ultrathin InxGa1−xN∕GaN (0.5&amp;lt;x&amp;lt;1) heterostructures, in contrast to bulk InN exhibiting a strong surface electron accumulation, free electrons mostly tend to accumulate at the buried InGaN∕GaN interface. We have also found that the low-field mobility in the InGaN∕GaN heterostructures is strongly limited by the buried interface roughness which causes more than 95% of all scattering events occurred by two-dimensional electron transport under low electric field conditions.

Low temperature electric transport properties in hydrogenated microcrystalline silicon films

The dark conductivity of microcrystalline silicon (μc-Si:H) films, deposited in a RF-PECVD system varying the RF power in the 15–100 W range, has been investigated as a function of the temperature. Under low electric field condition (10 3 V/cm), the conductivity of the samples as a function of the exponential of T − 1/4 presents a linear behaviour in the measured temperature range. The density of states near the Fermi level, the range of hopping and the activation energy for hopping have been evaluated using the diffusion model. A correlation between the hopping parameters and the crystallinity degree has been found.

Dynamics of an atmospheric pressure plasma plume generated by submicrosecond voltage pulses

Nonequilibrium plasmas driven by submicrosecond high voltage pulses have been proven to produce high-energy electrons, which in turn lead to enhanced ionization and excitations. Here, we describe a device capable of launching a cold plasma plume in the surrounding air. This device, “the plasma pencil,” is driven by few hundred nanosecond wide pulses at repetition rates of a few kilohertz. Correlation between current-voltage characteristics and fast photography shows that the plasma plume is in fact a small bulletlike volume of plasma traveling at unusually high velocities. A model based on photoionization is used to explain the propagation kinetics of the plasma bullet under low electric field conditions.

High efficiency blue‐violet optical modulators of ZnSe/ZnMgSSe asymmetric coupled quantum wells

AbstractWe report a high efficiency blue‐violet optical modulator consisting of ZnSe/ZnMgSSe asymmetric‐coupled quantum wells (ACQWs). The modulator devices were designed based on the finite element method in the framework of the effective‐mass approximation and grown by molecular beam epitaxy (MBE) systematically. The new device with an electron‐resonant type ACQW of [ZnSe (6 ML)/ZnMgSSe (2 ML)/ZnSe (12 ML)] has revealed a large Stark shift of ΔE ∼ 34 meV at room temperature in low electric field condition of 480 kV/cm. The maximum modulation depth is 51% with transmission configuration, and the devices show very stable operation. Differential absorption coefficients Δα between reverse bias of 0 and 24V are –26000 cm–1 at the ground state exciton resonance (E e1–hh1), and +11500 cm–1 in transparent region below the ground state, which is promising for practical waveguide optical modulators for the short wavelength. (© 2006 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Theoretical investigation of electron-phonon interaction in one-dimensional silicon quantum dot array interconnected with silicon oxide layers

Electronic and phononic states and their interactions in one-dimensional arrays of Si quantum dots interconnected with thin oxide layers is theoretically investigated. Electronic states under low electric field condition are obtained in the Kronig-Penny potential. Approximate expression for phonon wave functions is developed and numerically calculated using the linear atomic chain model. Simulated dispersion relation shows acoustic phonon modes, phonon band gaps, and confined optical phonon modes. Electron-phonon scattering rate is written using a one-dimensional expression. Intraminiband scattering rates and energy relaxation rates are simulated both for absorption and emission processes. The scattering rate varies from 10 12 to 10 14 , depending on the initial electron energy. The scattering rate for absorption/emission processes rapidly decreases at near the top/bottom of minibands due to limited number of phonon branches that can mediate the scattering processes. Negative energy relaxation rate is observed near the bottom of minibands, which is due to larger scattering rate for absorption process and smaller phonon energy mediating the scatterings for emission process. The scattering rate for absorption decreases rapidly with decreasing temperature. Once the temperature drops down to 100 K, the energy relaxation rate for emission process dominates the absorption process.

Carrier lifetime under low and high electric field conditions in semi-insulating GaAs

The mobility lifetime product of holes and electrons under low electric field conditions was determined by alpha spectroscopy using SI-GaAs as a photo conductivity detector. The lifetime in high electric field (≥ 10 4V/cm) of electrons was investigated with Schottky diodes. Both results were analyzed as a function of substrate resistivity and trap concentrations. We identified the ionized arsenic antisite defect (EL2 +) as the dominant electron trap in the high field region and determined the capture cross-section as being (8.0 ± 0.6) × 10 −14 cm 2.