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Pure VO2, GexV1−xO2 (x < 0.2), and AlxV1−xO2 (x ≤ 0.02) exhibit above room temperature the well-known insulator-metal-transition (IMT) (at TIMT ≅ 340 K). In addition, AlxV1−xO2 exhibits an insulator-insulator-transition (IIT) at TIIT < TIMT. Both transitions can be induced either by external or by Joule heating. Both leave prominent marks on the I–V characteristics of the investigated samples, IIT at low currents and IMT at high currents. Reported herein is a comparative study of the I–V characteristics of needle-like pure and doped VO2 single crystals obtained with pulsed currents of various durations and with DC, in an attempt to separate thermal from non-thermal electric field effects. Identification of the Poole–Frenkel effect (a non-thermal electric field effect) in the I–V characteristics of the doped crystals may play an important role in a long-standing debate on the mechanism of IMT. Such an identification was obtained in this investigation for several Ge- and Al-doped VO2 crystals, so far only in narrow ranges of electric fields (<2000 V/cm) and pulse durations (≤1 ms) above which the non-linear conductivity of the crystals is dominated by Joule heating. [ABSTRACT FROM AUTHOR]

Nanostructured zirconia and gold films (ns-Au/ZrOx ) have been demonstrated as devices characterized by non-linear and hysteretic electrical behavior, with short-term memory and potentiation/depression activity. Here we investigate the conduction mechanisms regulating the non-linear behavior of the nanostructured bilayer Au/ZrOx films. In particular, we investigated the hysteretic I-V curves following the Chua’s approach to memristive systems and separately modelling ion migration and electron transport in the films. The conduction mechanisms exhibited by the bilayered nanostructured system are strongly influenced by the nanogranular morphology that dynamically changes because of electrical stimuli; structural rearrangements are particularly promoted by intense local electric fields and high mobility along bottlenecks and edges in the microstructure. Electron transport is accounted for the Schottky barrier at the electrode interfaces and Poole-Frenkel effect in the bulk nanogranular material, according to a dynamic reorganization of the cluster-assembled network. A model for Poole-Frenkel effect is here discussed to include saturation of the Coulombic traps in the high applied field regime; the proposed model has been validated with experimental voltage ramps with varying sweep-velocity and at different temperatures (from 300 to 200 K), as also by a power exponent parameter analysis. [ABSTRACT FROM AUTHOR]

The presence of high contact resistance at the metal–organic semiconductor interface is a crucial issue in performance of organic field-effect transistors. In this report, an analytical expression of gate-voltage-dependent contact resistance has been derived for bottom contact organic field-effect transistor geometry. In this derivation, the thermionic injection mechanism, gate-voltage-dependent carrier mobility in the vicinity of the metal–organic semiconductor interface, and the Poole–Frenkel barrier lowering effect of the injection barrier have been taken into account. The developed analytical expression has been fitted with published data of a pentacene-based organic field-effect transistor. From the fit, hopping site density, interfacial charge density, and maximum mobility, near metal–organic semiconductor contact has been extracted. Also, numerical plots for output and transfer characteristics are plotted. [ABSTRACT FROM AUTHOR]

The paper discusses the basic mechanisms of conductivity in silicon nano/micro structures. The object of the study is porous silicon doped with erbium impurity from an aqueous solution of erbium nitrate Er(NO3)3⋅5H2O by temperature annealing in a diffusion furnace at a temperature of 800°C for 1 h. Comparative characteristics of current-voltage and capacitance-voltage correlations describing regular changes in the mechanisms of current flow and charge capture in the studied samples are presented. The results of the work qualitatively and quantitatively describe the temporary change in the electrical characteristics of porous silicon, which can be taken into account by technologists for better understanding the mechanisms of current transfer in luminescent structures of porous silicon with erbium ions, as well as in the study and manufacture of light-emitting diodes based on it. [ABSTRACT FROM AUTHOR]

In this paper, the electrical performance of a‐Si TFT product on adjustable frequency display is studied. It is found that panel flicker behavior is related to a‐Si channel characteristics, which is related to the TFT Cgs capacitance increase at low display frequency. And it is also found that the relationship between brightness fluctuations and TFT leakage current affected by Poole‐Frenkel effect. By optimizing TFT process parameter to reduce the change of Cgs capacitance and reduce TFT leakage current in Poole‐Frenkel region, panel flicker performance is obviously improved. As a result, gaming display product can meet the G‐sync optical standard requirement. [ABSTRACT FROM AUTHOR]

The single crystals of TlGaTe2 were grown by the Bridgman method. The current–voltage characteristics were performed for obtained crystals and it was determined that the Poole–Frenkel effect occurs in the nonlinear region of the current in the directions parallel and perpendicular to the crystallographic axis. The calculated values of the concentration of ionized centers N t , the mean free path λ , the values of the Frenkel coefficient β and the shape of the potential well in TlGaTe2 crystals are determined. [ABSTRACT FROM AUTHOR]

Space charge accumulation in polymer is a key problem for the electrical aging of insulation under DC condition. Space charge accumulation is strongly determined by the charge injection rate. The estimation of charge injection with steady state current contains the extraction current and is not accurate. This paper proposes a quantitative estimation method of the charge injection at the metal/polymer interface with space charge and current simultaneous measurement. A double-layer sample with a blocking layer is employed to make a quasi-unipolar condition to remove the extraction current. In addition, the displacement current is removed by considering the change in electric field on the electrode. The relationship between the electrode electric field and the pure injection current is analyzed. It is found that the square root of electric field intensity and the logarithm of injection current at the Al/LDPE (low density polyethylene) interface are linear with each other. The coefficients β for negative and positive charge injection at Al/LDPE interface are about 8.44 × 10−24 and 8.32 × 10−24, respectively. It indicates that both negative and positive charge injection at Al/LDPE interface fit the mathematical relationship of the Poole–Frenkel effect, rather than the Schottky effect which is mostly used in the study on the charge transport at polymer/metal. The negative and positive charge injection barriers are 1.23 and 1.24 eV, respectively. [ABSTRACT FROM AUTHOR]

In this work, we have reported the temperature-dependent resistive switching (RS) behavior observed in (1-x)CuI.(x)La 0.7 Sr 0.3 MnO 3 nanocomposites with 0.001 < x < 0.05 within the temperature range of 150 K to 300 K. Here, we observed bipolar and interface-type RS behavior, where the resistance can be altered to its previous state by the application of an opposite bias voltage. The extensive analysis of the current versus voltage data for different compositions at room temperature revealed that the dominating transport mechanisms in the low and high bias regions, respectively, were Schottky emission and Poole–Frenkel effect. The enhanced switching response of the RS medium after the addition of La 0.7 Sr 0.3 MnO 3 can be attributed to the oxygen vacancy-induced conduction which was confirmed by X Ray Photoelectron Spectroscopy (XPS) measurements. In the endurance test, the highest ON/OFF ratio averaged over 100 cycles was observed to be 4.2 ± 1.1 and 3.8 ± 0.3 for x = 0.001 and 0.02 respectively at T = 300K. At T = 250 K, we obtained the optimal ON/OFF ratio of 19.8 ± 1.8 for x = 0.001 and 22.7 ± 4.1 for x = 0.02. The investigation of current versus voltage graphs for T = 250 K, 200 K, and 150 K further confirmed Schottky emission and the Poole–Frenkel effect as the dominating transport mechanisms at lower temperatures. [ABSTRACT FROM AUTHOR]

In this paper, we present the results of our systematic investigations of the resistive switching characteristics of HfO2-based metal–insulator–metal structures using four different metal bottom electrode (BE) materials, namely Au, Al, Pt and Cu. Ag is used as the top electrode for all these resistive random access memory devices. On one hand, Au and Pt show lower set and reset voltages, whereas the Pt electrode has a higher resistance ratio (Roff/Ron) ~ 105). On the other hand, Al and Cu exhibit multilevel switching during the reset process. Thus, the oxygen affinity of the BE is expected to result in the formation of an interfacial layer with the active (HfO2) layer. Furthermore, conduction mechanisms have been studied for the various regions in the high resistance state (HRS) curves of all these devices. It is found that the Poole–Frenkel effect is more dominant at higher voltages (> 1 V) in the HRS curve. Therefore, it is essential to elucidate the appropriate BE material and optimum active switching layer to understand the conduction mechanisms for the resistive switching phenomenon. [ABSTRACT FROM AUTHOR]

The aim of this study is to give characterization of silicon p+/n/n+ detectors for the monitoring systems of the Large Hadron Collider machine at CERN with the focus on justifying the choice of silicon resistivity for the detector operation at the temperature of 1.9–10 K. The detectors from n-type silicon with the resistivity of 10, 4.5, and 0.5 kΩ cm were investigated at the temperature from 293 up to 7 K by the Transient Current Technique with a 660 nm pulse laser and alpha-particles. The shapes of the detector current pulse response allowed revealing a paradox in the properties of shallow donors of phosphorus, i.e., native dopants in the n-type Si. There was no carrier freeze-out on the phosphorus energy levels in the space charge region (SCR), and they remained positively charged irrespective of temperature, thus limiting the depleted region depth. As for the base region of a partially depleted detector, the levels became neutral at T < 28 K, which transformed silicon to an insulator. The reduction of the activation energy for carrier emission in the detector SCR estimated in the scope of the Poole-Frenkel effect failed to account for the impact of the electric field on the properties of phosphorus levels. The absence of carrier freeze-out in the SCR justifies the choice of high resistivity silicon as the only proper material for detector operation in a fully depleted mode at extremely low temperature. [ABSTRACT FROM AUTHOR]

The impact of dislocation density on off-state leakage current in avalanche-capable gallium nitride (GaN)-on-GaN vertical p-n diodes is experimentally demonstrated and studied. At first, the presence of avalanche breakdown was confirmed on p-n diodes grown on bulk GaN substrates with dislocation density ranging from 1e4 to 1e6 cm−2. The impact of dislocation density on off-state leakage current was then compared and analyzed on devices with confirmed stable avalanche behavior. The devices in the 1e6-cm−2 region show higher leakage current and a more variable-range-hopping-dominated leakage process, while the Poole–Frenkel effect starts showing more influence on the devices in the 1e4-cm−2 region, especially under medium and high average electric field beyond 1.0 MV $\cdot $ cm−1. [ABSTRACT FROM AUTHOR]

Thick cubic and sp2-bonded boron nitride (cBN and sp2BN) films are deposited on Ti substrates by plasma jet enhanced chemical vapor deposition using the chemistry of fluorine, and their direct current-voltage characteristics are studied for Ni-BN-Ti capacitor structures. The resistivity of the cBN film measured at room temperature is of the order of 108 Ωcm, which is three to four orders of magnitude lower than that of the sp2BN film. At high electric fields, Frenkel-Poole emission dominates the conduction of the sp2BN film, while thermionic emission is better able to describe the conduction of the cBN film at temperatures up to 473 K. A lower leakage current indicates lower densities of carriers and trap sites associated with defects, suggesting that a higher-quality cBN film with higher crystallinity and stoichiometry is potentially promising as an ultrahard dielectric material in high temperature condition. [ABSTRACT FROM AUTHOR]

PbTiO3 with oxygen-vacancy-stabilized d8 ion substitution has attracted significant attention as a promising photo-ferroelectric material, but less effort to understand the effect of defect structures on its macroscopic properties limits further modification of the functionality via defect engineering. Herein, a comparable investigation of highly-(111) oriented PbTiO3 (PTO) and PbTi0.9Ni0.1O3 (PTN) thin films is reported to realize the critical role of defect structures on the evolution of electrical and photovoltaic properties. It is found that the PTO thin film shows the space-charge-limited-current mechanism, while the PTN thin film obeys the Poole-Frenkel emission mechanism. Also, the dielectric abnormal peak emerges in the PTN thin film. Notably, the ferroelectric polarization still keeps a large value but the band gap is lowered, and thus a significant increment of photovoltaic properties is achieved in the PTN thin film. These experimental results can be well explained if the formation of dopant-vacancy complexes is taken into account. [ABSTRACT FROM AUTHOR]

We have performed Monte-Carlo simulations of the charge carrier transport in a model molecularly doped polymer using three most popular hopping theories (the dipolar glass model, the Gaussian disorder model and an intermediate between them) in a wide range of applied electric fields and temperatures. Time of flight transients have been computed and analyzed in logarithmic coordinates to study the Poole-Frenkel field dependence, the non-Arrhenius mobility temperature dependence and the nondispersive versus dispersive current shapes. We also have made an attempt to estimate the total disorder energy directly from simulation data at the lowest electric field thus checking the consistency of the model fitting. Computational results have been compared with the analytical and experimental information available in the literature. [ABSTRACT FROM AUTHOR]

We present a detailed investigation on temperature-dependent current conduction through thin tunnel oxides grown on degenerately doped n-type silicon (n+-Si) under positive bias (VG) on heavily doped n-type polycrystalline silicon (n+-polySi) gate in metal-oxide-semiconductor devices. The leakage current measured between 298 and 573K and at oxide fields ranging from 6 to 10MV/cm is primarily attributed to Poole-Frenkel (PF) emission of trapped electrons from the neutral electron traps located in the silicon dioxide (SiO2) band gap in addition to Fowler-Nordheim (FN) tunneling of electrons from n+-Si acting as the drain node in FLOating gate Tunnel OXide Electrically Erasable Programmable Read-Only Memory devices. Process-induced neutral electron traps are located at 0.18 eV and 0.9 eV below the SiO2 conduction band. Throughout the temperature range studied here, PF emission current IPF dominates FN electron tunneling current IFN at oxide electric fields Eox between 6 and 10MV/cm. A physics based new analytical formula has been developed for FN tunneling of electrons from the accumulation layer of degenerate semiconductors at a wide range of temperatures incorporating the image force barrier rounding effect. FN tunneling has been formulated in the framework of Wentzel-Kramers-Brilloiun taking into account the correction factor due to abrupt variation of the energy barrier at the cathode/oxide interface. The effect of interfacial and near-interfacial trapped-oxide charges on FN tunneling has also been investigated in detail at positive VG. The mechanism of leakage current conduction through SiO2 films plays a crucial role in simulation of time-dependent dielectric breakdown of the memory devices and to precisely predict the normal operating field or applied floating gate (FG) voltage for lifetime projection of the devices. In addition, we present theoretical results showing the effect of drain doping concentration on the FG leakage current. [ABSTRACT FROM AUTHOR]

A detailed study of the effect of off-center donor ion (Sc3+) substitution on structural, microstructural, optical, dielectric, electrical, and ferroelectric properties of morphotropic composition of lead zirconate titanate electroceramics with the stoichiometric formula Pb0.85Sc0.10Zr0.53Ti0.47O3 (PSZT) and synthesized using a high energy solid-state reaction technique was carried out. Powder x-ray diffractometry was used to identify the stabilized tetragonal phase (space group P4mm) with considerably reduced tetragonal strain, c=a=1.005. An analysis of the thermal dependence of the Raman results indicated a smooth displacive (ferroelectric-paraelectric) phase transition as revealed by the observed disappearance of the soft modes A1 (1TO) and A1 (2TO) above 460K. The dielectric response of Pt/PSZT/Pt metal-ferroelectric-metal capacitors was probed over a wide range of thermal excursions (85-600K) and ac signal frequencies (10²-106 Hz). Thermally activated dynamic and static conduction processes indicate hopping conduction mechanism (Eact ≤0.015 eV) and the formation of small polarons caused by the electron and/or hole-lattice (phonon) interaction (Eact ≥0.1 eV) at low (100-300K) and high temperatures (300-600 K), respectively. The reduction in remnant polarization obtained is in good agreement with the largely reduced tetragonal strain observed in this sample, (Pr ∝√c/a-1). DC conduction is dominated by Poole-Frenkel mechanism that assumes a Coulombic attraction between detrapped electrons and positively charged stationary defect species in the polycrystalline matrix. [ABSTRACT FROM AUTHOR]

The conduction mechanism(s) of gate leakage current JG through thermally grown silicon dioxide (SiO2) films on the silicon (Si) face of n-type 4H-silicon carbide (4H-SiC) has been studied in detail under positive gate bias. It was observed that at an oxide field above 5 MV/cm, the leakage current measured up to 303 °C can be explained by Fowler-Nordheim (FN) tunneling of electrons from the accumulated n-4H-SiC and Poole-Frenkel (PF) emission of trapped electrons from the localized neutral traps located at ≈2.5 eV below the SiO2conduction band. However, the PF emission current IPF dominates the FNelectron tunneling current IFN at oxide electric fields Eox between 5 and 10 MV/cm and in the temperature ranging from 31 to 303 °C. In addition, we have presented a comprehensive analysis of injection of holes and their subsequent trapping into as-grown oxide traps eventually leading to time-dependent dielectric breakdown during electron injection under positive bias temperature stress (PBTS) in n-4H-SiC metal-oxide-silicon carbide structures. Holes were generated in the heavily doped n-type polycrystalline silicon (n+-polySi) gate (anode) as well as in the oxide bulk via band-to-band ionization by the hot-electrons depending on their energy and SiO2 film thickness at Eox between 6 and 10 MV/cm (prior to the intrinsic oxide breakdown field). Transport of hot electrons emitted via both FN and PF mechanisms was taken into account. On the premise of the hole-induced oxide breakdown model, the time- and charge-to-breakdown (tBD and QBD) of 8.5 to 47 nm-thick SiO2 films on n-4H-SiC were estimated at a wide range of temperatures. tBD follows the Arrhenius law with activation energies varying inversely with initial applied constant field Eoxsupporting the reciprocal field (1/E) model of breakdown irrespective of SiO2film thicknesses. We obtained an excellent margin (6.66 to 6.33 MV/cm at 31 °C and 5.11 to 4.55 MV/cm at 303 °C) of normal operating field for a 10-year projected lifetime of 8.5 to 47 nm-thick SiO2 films on n-4H-SiC under positive bias on the n+-polySi gate. Furthermore, the projected maximum operating oxide field was little higher in metal gate devices compared to n+-polySi gate devices having an identically thick thermal SiO2 films under PBTS. [ABSTRACT FROM AUTHOR]

The influence of deep-level defects localized in spacer layers on the tunneling current in a w-AlN/GaN (0001) double-barrier structure is studied. It is shown that the current value essentially depends on the nature and spatial distribution of defects. New effects (screening of built-in fields, negative feedback, fixing of current peaks at high temperature) and a new mechanism of formation of resonances and tunneling current hysteresis caused by deep centers are established. The results of calculation agree with a number of experimental data on the position and temperature dependence of the current peak. It is noted that the current bistability can be caused by multicharged deep centers localized near the heteroboundaries of a double-barrier structure. Due to the defects, electric field in the barriers can reach values, at which the Poole-Frenkel effect should be taken into account. [ABSTRACT FROM AUTHOR]

Electronic conduction through proton-conducting electrolytes significantly impairs the efficiency of protonic ceramic cells (PCCs). In this study, we explore the electron and ion mixed transport properties of four common protonic ceramics, BaZr 0.8 Y 0.2 O 3-δ (BZY82), BaZr 0.7 Ce 0.2 Y 0.1 O 3-δ (BZCY721), BaZr 04 Ce 0.4 Y 0.1 Yb 0.1 O 3-δ (BZCYYb4411), and BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ (BZCYYb1711). It marks the first instance of investigating these properties under operation-specific scenarios: fuel side of electrolysis cell, air side of electrolysis cell, fuel side of fuel cell, and air side of the fuel cell. BZCYYb1711 exhibits the highest ionic conductivity, but two to three times higher electronic leakage when exposed to oxygen-containing environments than the others. BZY82 exhibits approximately two times higher electronic leakage in a hydrogen-containing environment. BZCY721 demonstrates excellent ion transport numbers (∼0.95) across these four operating conditions. BZCYYb4411 behaves quite similarly to BZCY721. The most challenging operating environment for all candidates is the air side of fuel cell mode. This mode leads to a high initial electronic leakage, followed by a significant increase with polarization. The probable cause for this behavior is a H 2 -free, polarization-induced reduction that leads to the formation of V O •. The electron small polaron associated with V O • is released by the electrical field due to the Poole-Frenkel effect. ZnO and NiO sintering aids are found to be detrimental to the ionic conductivity of the electrolytes. In particular, NiO substantially lowers the ion transport number. The correlation of the operation-specific electronic leakage to full cells is discussed. It is suggested that a rational PCC design should synergistically couple BZCYYb1711 at fuel side with BZCY4411 at air side to deliver a well-balanced performance and faradaic efficiency simultaneously, and the high temperature sintering process with a NiO fuel electrode should be shortened or replaced by ultra-fast sintering techniques or using a fuel electrode scaffold-infiltration fabrication strategy. • We studied proton conducting electrolytes' electronic leakage. • BZCYYb1711 excels in ionic conductivity but with higher leakage in O-rich settings. • BZY82 shows increased leakage in hydrogen-rich settings. • Needs for balancing efficiency & performance in protonic ceramic cells. [ABSTRACT FROM AUTHOR]

Nitrogen in group-IV semiconductors has become a well-established element of qubits capable of room-temperature operation. In silicon carbide, nitrogen can occupy different nonequivalent lattice sites, giving rise to different shallow donor states. We report a triplet fine structure in electronic transitions of nitrogen donors on the quasi-cubic carbon site in 4H silicon carbide with activation enthalpies of around 100 meV. The intensities of triplet components have a prominent dependence on the voltage bias. The activation enthalpies of the transitions exhibit the Poole–Frenkel effect, while no bias dependence is observed for the magnitude of splitting. A tentative explanation of the fine structure involves local symmetry changes due to stacking faults. [ABSTRACT FROM AUTHOR]

A n-4H SiC based diode is fabricated by an Au front metal contact to provide rectification at the metal-semiconductor (MS) junction, and a back ohmic contact is also obtained using Au metal with post-thermal heating. MS diode characteristics are investigated by current–voltage ( I - V ) measurements with a wide range of temperature from 80 K to 300 K. At each temperature, rectifying behavior is achieved and it is improved with an increase in temperature. Barrier height and ideality factor are calculated according to the thermionic emission (TE) model from linearity in the forward bias region of the ln I versus V plot. The experimental zero-bias barrier height ( Φ b 0 ) values are in a good agreement with literature, and at around room temperature the ideality factor (n ) reaches unity. At saturation regions in I - V curves, parasitic resistance values are derived by Ohm's law and the series resistance values are also reevaluated by Cheung's relation. Detailed I - V analysis is performed by modifying the TE model with an approximation of low barrier patches embedded in the main barrier height. Two linear relations in the characteristic plots of Φ b 0 and n indicate that double Gaussian distribution is a suitable current conduction model via localized barrier patches at low temperatures. Additionally, reverse bias current flow is analyzed under the dominant effect of Poole-Frenkel emission associated with the interfacial traps. According to the characteristic electric field-dependent current density plot, emission barrier height and relative dielectric constant for n-4H SiC are calculated. [ABSTRACT FROM AUTHOR]

Resistive random access memory (RRAM) has been intensively investigated for nearly two decades. However, RRAM has not been applied widely in the market because of the poor characteristics, such as reliability and uniformity, which could be improved by the accurate comprehension of the mechanism. In this paper, a model based on percolation theory is proposed to simulate the I-V characteristics of ZnO resistive switching memory. It demonstrates that three different conductions of space charge limited current, Poole–Frenkel effect, and thermionic emission are determined by the relationship between the oxygen vacancy concentration and the bias. Furthermore, this model well explains the effect of conductive filaments' diameter and compliance current on the I-V characteristics of ZnO resistive switching memory, which demonstrates the rationality of the percolation model. [ABSTRACT FROM AUTHOR]

We present for the first time a thorough investigation of trapped-hole induced gate oxide deterioration and simulation results of time-dependent dielectric breakdown (TDDB) of thin (7-25 nm) silicon dioxide (SiO2) films thermally grown on (0 0 0 1) silicon (Si) face of n-type 6H-silicon carbide (n-6H-SiC). Gate oxide reliability was studied during both constant voltage and current stress with positive bias on the degenerately doped n-type poly-crystalline silicon (n+-polySi) gate at a wide range of temperatures between 27 and 225 °C. The gate leakage current was identified as the Poole-Frenkel (PF) emission of electrons trapped at an energy 0.92 eV below the SiO2 conduction band. Holes were generated in the n+-polySi anode material as well as in the oxide bulk via band-to-band ionization depending on the film thickness tox and the energy of the hot-electrons (emitted via PF mechanism) during their transport through oxide films at oxide electric fields Eox ranging from 5 to 10 MV/cm. Our simulated time-to-breakdown (tBD) results are in excellent agreement with those obtained from time consuming TDDB measurements. It is observed that irrespective of stress temperatures, the tBD values estimated in the field range between 5 and 9 MV/cm better fit to reciprocal field (1/E) model for the thickness range studied here. Furthermore, for a 10 year projected device lifetime, a good reliability margin of safe operating field from 8.5 to 7.5 MV/cm for 7 nm and 8.1 to 6.9MV/cmfor 25nmthick SiO2 was observed between 27 and 225 °C. [ABSTRACT FROM AUTHOR]

In this paper, we investigate dielectric charging process in capacitive structure dielectrics under bias voltage. We particularly focus on the case of Si3N4 dielectric layers. The main defects in silicon nitride involved in electronic transport are identified as shallow traps. A new model for dielectric charging is presented with trap assisted tunneling effect as interfacial electronic transport mechanism and Frenkel-Poole and hopping current as bulk transport mechanisms. Thanks to this model, electric field and charge carrier distribution in the dielectric layer can be calculated. The actuation bias shift versus time, which is responsible for RF capacitive structure failure, can also be determined. We find that after a 300 s actuation, the charge is concentrated in few nm in the dielectric layer and a voltage shift of few volts is calculated, depending on dielectric characteristics. [ABSTRACT FROM AUTHOR]

Electrical transport in chalcogenide-based phase change materials is an active area of research owing to the prominent role played by these materials in the field of information technology. Here, we present transport measurements (IV curves) obtained on line-cells of as-deposited amorphous phase change materials (Ge2Sb2Te5, GeTe, Ag4In3Sb66Te27) over a wide voltage and temperature range (300K to 160 K). The well defined geometry of our devices enables a description of the transport behavior in terms of conductivity vs. electric field. At higher temperatures (300K≥T≥220 K) and low to intermediate fields (F<20 V/µm), the data can be described within the framework of a previously developed model, which is based on multiple trapping transport together with 3D Poole-Frenkel emission from a two-center Coulomb potential. Based on this model, we observe a temperature dependence of the inter-trap distance, which we can relate to a temperature dependence in the occupation of the defect creating the Coulomb potential governing Poole-Frenkel emission. At higher fields and lower temperatures, the dependency of the IV curve on the electric field can be described by ln(I/I0)=(F/Fc)². By combining this contribution with that of the Poole-Frenkel emission, we can show that the slope at high fields, Fc, is independent of temperature. We argue that models based on direct tunneling or thermally assisted tunneling from a single defect into the valence band cannot explain the observed behavior quantitatively. [ABSTRACT FROM AUTHOR]

In this work, a metal–semiconductor diode in the form of Au/4H-SiC is fabricated, and the electrical properties of this device are systematically examined under dark and different illumination intensities. To perform this, the current–voltage (I–V) characteristics of the Schottky-type diode are analyzed at room temperature. The performance parameters such as saturation current ( I 0 ), barrier height ( Φ B ), ideality factor (n ) and series resistance ( R s ) are found to be illumination dependent. The reverse biased I - V characteristics under incident light indicate high photo-sensitivity as compared to the response at forward bias. Thus, this result is investigated in detail according to both Schottky and Poole–Frenkel effects. It is found that the Poole–Frenkel mechanism is dominant in the reverse biased region. The Au/4H-SiC Schottky junction has a strong photo-current response to the different illumination intensities and transient photocurrent characteristics of the fabricated device are studied at the illumination intensities of 50 and 100 mW/cm2. All experimental results indicate that the Au/4H-SiC Schottky diode, with a valuable response to the illumination together with change in illumination intensity, can be used for optoelectronic applications. [ABSTRACT FROM AUTHOR]

In this article, we separately investigate the role of electric field and device self-heating (SHE) in enhancing the charge emission process from Fe-related buffer traps (0.52 eV from Ec) in AlGaN/GaN high electron mobility transistors (HEMTs). The experimental analysis was performed by means of drain current transient (DCT) measurements for either: 1) different dissipated power (PD,steady) at constant drain-to-source bias (VDS,steady) or 2) constant PD,steady at different VDS,steady’s. We found that: 1) an increase in PD,steady yields an acceleration in the thermally activated emission process, consistently with the temperature rise induced by SHE and 2) on the other hand, the field-effect turned out to be negligible within the investigated voltage range, indicating the absence of the Poole–Frenkel effect (PFE). A qualitative analysis based on the electric field values obtained by numerical simulations is then presented to support the interpretation and conclusions. [ABSTRACT FROM AUTHOR]

We propose a model for dark current induced by metallic contamination in a CMOS image sensor. Based on Shockley-Read-Hall kinetics, the expression of dark current proposed accounts for the electric field enhanced emission factor due to the Poole-Frenkel barrier lowering and phonon-assisted tunneling mechanisms. To that aim, we considered the distribution of the electric field magnitude and metal atoms in the depth of the pixel. Poisson statistics were used to estimate the random distribution of metal atoms in each pixel for a given contamination dose. Then, we performed a Monte-Carlo-based simulation for each pixel to set the number of metal atoms the pixel contained and the enhancement factor each atom underwent, and obtained a histogram of the number of pixels versus dark current for the full sensor. Excellent agreement with the dark current histogram measured on an ion-implanted gold-contaminated imager has been achieved, in particular, for the description of the distribution tails due to the pixel regions in which the contaminant atoms undergo a large electric field. The agreement remains very good when increasing the temperature by 15 °C. We demonstrated that the amplification of the dark current generated for the typical electric fields encountered in the CMOS image sensors, which depends on the nature of the metal contaminant, may become very large at high electric field. The electron and hole emissions and the resulting enhancement factor are described as a function of the trap characteristics, electric field, and temperature. [ABSTRACT FROM AUTHOR]

In many of the publications, over 50 per year for the last five years, the Poole-Frenkel-effect (PFE) is identified or suggested as dominating current mechanism to explain measured current-electric field dependencies in metal-insulator-metal (MIM) thin film stacks. Very often, the insulating thin film is a metal oxide as this class of materials has many important applications, especially in information technology. In the overwhelming majority of the papers, the identification of the PFE as dominating current mechanism is made by the slope of the current-electric field curve in the so-called Poole-Frenkel plot, i.e., logarithm of current density, j, divided by the applied electric field, F, versus the square root of that field. This plot is suggested by the simplest current equation for the PFE, which comprises this proportionality (ln(j/F) vs. F1/2) leading to a straight line in this plot. Only one other parameter (except natural constants) may influence this slope: the optical dielectric constant of the insulating film. In order to identify the importance of the PFE simulation studies of the current through MIM stacks with thin insulating films were performed and the current-electric field curves without and with implementation of the PFE were compared. For the simulation, an advanced current model has been used combining electronic carrier injection/ejection currents at the interfaces, described by thermionic emission, with the carrier transport in the dielectric, described by drift and diffusion of electrons and holes in a wide band gap semiconductor. Besides the applied electric field (or voltage), many other important parameters have been varied: the density of the traps (with donor- and acceptor-like behavior); the zero-field energy level of the traps within the energy gap, this energy level is changed by the PFE (also called internal Schottky effect); the thickness of the dielectric film; the permittivity of the dielectric film simulating different oxide materials; the barriers for electrons and holes at the interfaces simulating different electrode materials; the temperature. The main results and conclusions are: (1) For a single type of trap present only (donor-like or acceptor-like), none of the simulated current density curves shows the expected behavior of the PFE and in most cases within the tested parameter field the effect of PFE is negligibly small. (2) For both types of traps present (compensation) only in the case of exact compensation, the expected slope in the PF-plot was nearly found for a wider range of the applied electric field, but for a very small range of the tested parameter field because of the very restricting additional conditions: first, the quasi-fermi level of the current controlling particle (electrons or holes) has to be 0.1 to 0.5 eV closer to the respective band limit than the zero-field energy level of the respective traps and, second, the compensating trap energy level has to be shallow. The conclusion from all these results is: the observation of the PFE as dominating current mechanism in MIM stacks with thin dielectric (oxide) films (typically 30 nm) is rather improbable! [ABSTRACT FROM AUTHOR]

In order to develop and verify a dielectric breakdown model for bulk insulators thicker than 100 μm, the knowledge of the dominating conduction mechanism at high electric fields, or respectively voltages, is necessary. The dielectric breakdown is the electrical failure of an insulator. In some existing breakdown models, ohmic conduction is assumed as dominating conduction mechanism. For verification, the dominating dc conduction mechanism of bulk insulators at room temperature was investigated by applying high voltages up to 70 kV to the insulator until dielectric breakdown occurs. Four conduction models, namely, ohmic, space charge limited, Schottky, and Poole-Frenkel conduction, were employed to identify the dominating conduction mechanism. Comparing the calculated permittivities from the Schottky and Poole-Frenkel coefficients with experimentally measured permittivity, Schottky and Poole-Frenkel conduction can be excluded as dominating conduction mechanism. Based on the current density voltage characteristics (J-V-curve) and the thickness-dependence of the current density, space charge limited conduction (SCLC) was identified to be the dominating conduction mechanism at high voltages leading to dielectric breakdown. As a consequence, breakdown models based on ohmic conduction are not appropriate to explain the breakdown of the investigated bulk insulators. Furthermore, the electrical failure of the examined bulk insulators can only be described correctly by a breakdown model which includes SCLC as conduction mechanism. [ABSTRACT FROM AUTHOR]

Here, we report on the current transport mechanisms in AlN thin films deposited at a low temperature (i.e., 200 °C) on p-type Si substrates by plasma-enhanced atomic layer deposition. Structural characterization of the deposited AlN was carried out using grazing-incidence X-ray diffraction, revealing polycrystalline films with a wurtzite (hexagonal) structure. Al/AlN/ p-Si metal-insulatorsemiconductor (MIS) capacitor structures were fabricated and investigated under negative bias by performing current-voltage measurements. As a function of the applied electric field, different types of current transport mechanisms were observed; i.e., ohmic conduction (15.2-21.5 MV/m), Schottky emission (23.6-39.5 MV/m), Frenkel-Poole emission (63.8-211.8 MV/m), trap-assisted tunneling (226-280 MV/m), and Fowler-Nordheim tunneling (290-447 MV/m). Electrical properties of the insulating AlN layer and the fabricated Al/AlN/p-Si MIS capacitor structure such as dielectric constant, flat-band voltage, effective charge density, and threshold voltage were also determined from the capacitance-voltage measurements. [ABSTRACT FROM AUTHOR]

Lattice-matched Pt/Au-In0.17Al0.83N/GaN hetreojunction Schottky diodes with circular planar structure have been fabricated and investigated by temperature dependent electrical measurements. The forward and reverse current transport mechanisms are analyzed by fitting the experimental current-voltage characteristics of the devices with various models. The results show that (1) the forward-low-bias current is mainly due to the multiple trap-assisted tunneling, while the forward-high-bias current is governed by the thermionic emission mechanism with a significant series resistance effect; (2) the reverse leakage current under low electric fields (<6 MV/cm) is mainly carried by the Frenkel-Poole emission electrons, while at higher fields the Fowler-Nordheim tunneling mechanism dominates due to the formation of a triangular barrier. [ABSTRACT FROM AUTHOR]

This paper describes 3D particle-in-cell simulation of bipolar charge injection and transport through nanocomposite film comprised of ferroelectric ceramic nanofillers in an amorphous polymer matrix. The classical electrical double layer (EDL) model for a monopolar core is extended (eEDL) to represent the nanofiller by replacing it with a dipolar core. Charge injection at the electrodes assumes metal-polymer Schottky emission at low to moderate fields and Fowler-Nordheim tunneling at high fields. Injected particles migrate via field-dependent Poole-Frenkel mobility and recombine with Monte Carlo selection. The simulation algorithm uses a boundary integral equation method for solution of the Poisson equation coupled with a second-order predictor-corrector scheme for robust time integration of the equations of motion. The stability criterion of the explicit algorithm conforms to the Courant-Friedrichs-Levy limit assuring robust and rapid convergence. The model is capable of simulating a wide dynamic range spanning leakage current to pre-breakdown. Simulation results for BaTiO3 nanofiller in amorphous polymer matrix indicate that charge transport behavior depend on nanoparticle polarization with anti-parallel orientation showing the highest leakage conduction and therefore lowest level of charge trapping in the interaction zone. Charge recombination is also highest, at the cost of reduced leakage conduction charge. The eEDL model predicts the meandering pathways of charge particle trajectories. [ABSTRACT FROM AUTHOR]

Highly efficient organic solar cells typically comprise donor-acceptor blend layers facilitating effective splitting of excitons. However, the charge carrier mobility in the blends can be substantially smaller than in neat materials, hampering the device performance. Currently, available mobility models do not describe the transport in blend layers entirely. Here, we investigate hole transport in a model blend system consisting of the small molecule donor zinc phthalocyanine (ZnPc) and the acceptor fullerene C60 in different mixing ratios. The blend layer is sandwiched between p-doped organic injection layers, which prevent minority charge carrier injection and enable exploiting diffusion currents for the characterization of exponential tail states from a thickness variation of the blend layer using numerical drift-diffusion simulations. Trap-assisted recombination must be considered to correctly model the conductivity behavior of the devices, which are influenced by local electron currents in the active layer, even though the active layer is sandwiched in between p-doped contacts. We find that the density of deep tail states is largest in the devices with 1:1 mixing ratio (Et=0.14 eV, Nt=1.2×1018cm-3) directing towards lattice disorder as the transport limiting process. A combined field and charge carrier density dependent mobility model are developed for this blend layer. [ABSTRACT FROM AUTHOR]

We report the emission kinetics of a single-electron trap (E1, EC–0.63 eV) in Sn-doped (01) β-Ga2O3 crystals studied using deeplevel transient spectroscopy (DLTS). The time constant () of the electrons emitted from the trap level E1 was thoroughly investigated as a function of the temperature and the electric field (E-field). The temperature-dependence of E1 was extracted by both the temperature-scanning and isothermal modes of DLTS. It was found that the emission process accelerated exponentially from 200 K to 350 K. The E-field dependence of the emission time constant could be divided into two regimes for all measurement steps (250–325 K). In the low-electric-field regime, the emission time constant of the trap decreased slightly with a strengthened E-field. With a further enhancement of the E-field (E > 1.76 MV cm−1), the field-enhanced emission rate was accurately modeled by the Poole–Frenkel effect; the accelerated emission process was attributed to a reduction of the Coulomb well barrier for the donor-like trap E1. [ABSTRACT FROM AUTHOR]

In this paper, we propose a method for characterizing the trap energy distribution of polymers. The method can accurately extract the de-trapping current from the polarization current of the sample, thus overcoming the accuracy problem of the traditional isothermal relaxation current (IRC) method. Further application of this method on crosslinked polyethylene (XLPE) sheet samples revealed the effect of thermal degradation degree on the trap distribution of XLPE. At the recrystallization stage as polyethylene becomes re-crosslinked, the number of traps decreases. At the thermal-oxidative aging stage as the sample is seriously damaged, the number of traps increases. The de-trapping current of the sample thus exhibits a first decreasing and then increasing trend. [ABSTRACT FROM AUTHOR]

Ovonic threshold switch (OTS) has received great attention in neuromorphic computing due to its support for high-density synapse array as a selector and leaky-integration-firing functions Hodgkin-Huxley neurons. However, there is no simple and complete model for device simulation and integrated circuit design, which hindered application until now. In this work, we developed a compact physical model of OTS based on the Poole-Frenkel effect accompanied by the thermal dissipation effect for the first time. The thermal dissipation effect describes the energy flow between the device and the environment so that the model is more practical. Compared with previous experiments, the numerical results fairly fitted the electrical characteristics, demonstrating the model validity. In addition, the relation of the device performance with material and structure was deduced, which can facilitate optimizing the OTS device. The model will be useful for device design and implemented with high speed for simplicity. [ABSTRACT FROM AUTHOR]

The current–voltage characteristics of silicon photodiodes before and after irradiation by γ-quanta with an energy of 1.25 MeV and an irradiation dose of 0.5 mrad are investigated. It is established that the reverse currents are determined by the Poole–Frenkel mechanism in a strong electric field with the influence of electron–phonon interaction. A procedure is developed and the parameters of the electron–phonon interaction described by the single-coordinate configuration model are calculated from the reverse current–voltage characteristics. It is assumed that divacancy-oxygen centers in silicon, which determine the reverse photodiode currents, are formed due to γ-ray irradiation. [ABSTRACT FROM AUTHOR]

The performance of thin film metal-insulator-metal (MIM) diodes is investigated for a variety of large and small electron affinity insulators using ultrasmooth amorphous metal as the bottom electrode. Nb2O5, Ta2 O5, ZrO2, HfO2, Al2 O3, and SiO2 amorphous insulators are deposited via atomic layer deposition (ALD). Reflection electron energy loss spectroscopy (REELS) is utilized to measure the band-gap energy (EG) and energy position of intrinsic sub-gap defect states for each insulator. EG of as-deposited ALD insulators are found to be Nb2O5=3.8 eV, Ta2O5=4.4 eV, ZrO2=5.4 eV, HfO2=5.6 eV, Al2O3=6.4 eV, and SiO2=8.8 eV with uncertainty of ±0.2 eV. Current vs. voltage asymmetry, non-linearity, turn-on voltage, and dominant conduction mechanisms are compared. Al2O3 and SiO2 are found to operate based on Fowler-Nordheim tunneling. Al2O3 shows the highest asymmetry. ZrO2, Nb2O5, and Ta2O5 based diodes are found to be dominated by Frenkel-Poole emission at large biases and exhibit lower asymmetry. The electrically estimated trap energy levels for defects that dominate Frenkel-Poole conduction are found to be consistent with the energy levels of surface oxygen vacancy defects observed in REELS measurements. For HfO2, conduction is found to be a mix of trap assisted tunneling and Frenkel-Poole emission. Insulator selection criteria in regards to MIM diodes applications are discussed. [ABSTRACT FROM AUTHOR]

This paper presents the electrical properties of Al-doped ZnO (AZO) films directly grown on two types of p-type GaN thin films. The low-pressure p-GaN thin films (LP-p-GaN) exhibited structural properties of high-density edge-type threading dislocations (TDs) and compensated defects (i.e., nitrogen vacancy). Compared with high-pressure p-GaN thin films (HP-p-GaN), X-ray photoemission spectroscopy of Ga 3d core levels indicated that the surface Fermi-level shifted toward the higher binding-energy side by approximately 0.7 eV. The high-density edge-type TDs and compensated defects enabled surface Fermi-level shifting above the intrinsic Fermi-level, causing the surface of LP-p-GaN thin films to invert to n-type semiconductor. A highly nonlinear increase in leakage current regarding reverse-bias voltage was observed for AZO/LP-p-GaN. The theoretical fits for the reverse-bias voltage region indicated that the field-assisted thermal ionization of carriers from defect associated traps, which is known as the Poole-Frenkel effect, dominated the I-V behavior of AZO/LP-p-GaN. The fitting result estimated the trap energy level at 0.62 eV below the conduction band edge. In addition, the optical band gap increased from 3.50 eV for as-deposited AZO films to 3.62 eV for 300 °C annealed AZO films because of the increased carrier concentration. The increasing Fermi-level of the 300 °C annealed AZO films enabled the carrier transport to move across the interface into the LP-p-GaN thin films without any thermal activated energy. Thus, the Ohmic behavior of AZO contact can be achieved directly on the low-pressure p-GaN films at room temperature. [ABSTRACT FROM AUTHOR]

Electrical properties of n-Si/n-Si, p-Si/n-Si, and p--Si/n+-Si junctions fabricated by using surface-activated-bonding are investigated. The transmission electron microscopy/energy dispersive X-ray spectroscopy of the n-Si/n-Si interfaces reveals no evidence of oxide layers at the interfaces. From the current-voltage (I-V) and the capacitance-voltage (C-V) characteristics of the p-Si/n-Si and p--Si/n+-Si junctions, it is found that the interface states, likely to have formed due to the surface activation process using Ar plasma, have a more marked impact on the electrical properties of the p-Si/n-Si junctions. An analysis of the temperature dependence of the I-V characteristics indicates that the properties of carrier transport across the bonding interfaces for reverse-bias voltages in the p-Si/n-Si and p--Si/n+-Si junctions can be explained using the trap-assisted-tunneling and Frenkel-Poole models, respectively. [ABSTRACT FROM AUTHOR]

The forward and reversed biased current–voltage behaviors of the organic diode were detailed in a wide range of temperatures. In this diode, a donor–acceptor-conjugated copolymer system was constructed with poly((9,9-dioctylfluorene)-2,7-diyl-(2-dodecyl-benzo[1,2,3]triazole)) as a partner of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). Two-order of magnitude rectification ratio was achieved, and the temperature-dependent values of saturation current, zero-bias barrier height, and ideality factor were extracted according to the thermionic emission model. The temperature responses of these diode parameters showed an existence of inhomogeneity in the barrier height formation. As a result, the observed non-ideal behavior was explained by Gaussian distribution of barrier height where low-barrier regions are effective in the forward biased conduction mechanism at low temperatures. Together with this analysis, series resistances were evaluated using Cheung's functions and also density of interface states were investigated. On the other hand, reverse biased current flow was found under the dominant effect of Poole–Frenkel effects associated with these interfacial traps. The reverse current conduction mechanism was detailed by calculating characteristic field-lowering coefficients and barrier height values in the emission process from the trapped state in the range of temperatures of interest. [ABSTRACT FROM AUTHOR]

Measurements of deep trap spectra in bulk β-Ga2O3 crystals showed the parameters of the two dominant centers with levels near Ec-0.8 eV (E2) and Ec-1 eV(E3) are affected the electric field during deep level transient spectroscopy (DLTS). Both DLTS spectra measurements of the emission rates of the E2 and E3 traps and measurements of emission rates as a function of electric field from capacitance decay curves obtained at a fixed temperature (380 K) show that, for strong electric field with magnitude above ∼5 × 105 V.cm−1, the emission rates of these traps increase with increasing field. For the E2 traps, the increase is driven by phonon assisted tunneling. This points to the trap being an acceptor, which is consistent with reported attribution of the center to substitutional Fe acceptors. For the E3 trap, the field dependence indicates the dominant mechanism is the Poole–Frenkel effect, operable for Coulombic centers. It is concluded that this commonly observed trap is a deep donor. [ABSTRACT FROM AUTHOR]

Herein, as one of bias‐dependent channel leakage issues in p‐channel multilayered molybdenum ditelluride field‐effect transistors (m‐MoTe2 FETs), anomalous increase in off‐state current is reproducibly observed with increase in drain‐to‐gate voltage (VDG), even after hydrophobic, cyclic transparent optical polymer (CYTOP) encapsulation. For elucidation on the behind mechanism for the phenomena, drain‐ and gate‐bias dependent channel leakage currents are systematically analyzed in the range of temperature 100 to 380 K. Surprisingly, analysis on trap‐assisted indirect tunneling current substantiates that the off‐state current is mainly attributed to gate‐induced drain leakage (GIDL) current associated with band bending in m‐MoTe2 FETs. Moreover, linear slope (0.00163) of ln (IDS/F) versus F1/2 plot and its coincidence with theoretical value (0.00148) identify that thermal emission associated with Poole–Frenkel effect is strongly involved at low drain bias of −1.1 V (e.g., effective barrier height, ϕB ≈ 0.61 eV), whereas GIDL current becomes more predominant at high drain bias of −3.1 V (ϕB ≈ 0.51 eV). Thus, in‐depth understanding on the origin of anomalous leakage current and its systematic validation would be beneficial for the development of novel devices and circuits based on transition metal chalcogenides (TMDCs). [ABSTRACT FROM AUTHOR]

The correlation between threading dislocations and leakage current in a CdZnTe(001)/GaAs epilayer grown by close-spaced sublimation was studied using scanning electron microscopy, Kelvin probe force microscopy, conductive atomic force microscopy (C-AFM) and current–voltage (I–V) systems. The electrostatic potential differences between the charged dislocations and the CZT epitaxial film were found to be lower than those in bulk CZT crystal. C-AFM tests in the CZT epitaxial film under forward bias demonstrated that dislocations guided the high current leakage paths. The leakage current at dislocation sites was found to be two orders higher than that at dislocation-free areas with an applied bias of 5 V. The rapid increase in leakage current under applied bias in the range of 3.5–7.5 V was associated with the Poole–Frenkel effect, where high leakage current arises from the high density of trapped carriers escaping from the traps segregated around dislocations. [ABSTRACT FROM AUTHOR]

The possibility of predicting the magnitude of the trapped charge in the buried oxide of silicon-on-insulator structures using the Poole–Frenkel effect is investigated. The conditions for the Poole–Frenkel effect in this layer are determined by measuring and modeling the current–voltage characteristics of buried silicon oxide at various temperatures. Processes occurring in the buried oxide when measuring the current–voltage characteristics and during annealing are considered. The conditions of thermal-field treatment of the buried oxide for imitation of the radiation effect using injection are determined. The dependence of the magnitude of the accumulated positive charge in buried silicon oxide due to injection on the Poole–Frenkel current is evaluated. The possibility of applying the Poole–Frenkel effect for evaluating the imperfection of the buried oxide when fabricating microcircuits with increased radiation-dose resistance is shown. [ABSTRACT FROM AUTHOR]

In order to explore the space charge behavior of liquid silicone rubber (LSR) the pulsed electroacoustic (PEA) method has been applied. Due to the elastic nature of LSR, the PEA setup was optimized to ensure a constant contact pressure and thus a constant thickness of the LSR samples. For each sample, the temperature of the ground and the high-voltage electrode was permanently measured. The space charge behavior was investigated for neat LSR and for LSR samples with two different amounts of nanoscaled carbon black (CB). The results show in general a formation of homocharges at both electrodes. At 20 °C, the negative charge from the cathode moves towards the anode in the case of neat LSR. With increasing amount of CB, the negative charge is trapped near the cathode and the charge migration is suppressed. At higher temperature, an increasing amount of positive homocharges at the anode is observed, which is suppressed for LSR with CB nanofillers. The mean charge density between the electrodes is evaluated during polarization and depolarization measurement. The results show that the mean charge density increases with temperature and electric field strength, which is explained by the Schottky and Poole-Frenkel effect. In addition, it is observed that the mean attenuation rate during the depolarization time increases with increasing amount of CB nanofillers. [ABSTRACT FROM AUTHOR]