Leakage Behavior Research Articles

Effect of Carbon Doping on Charging/Discharging Dynamics and Leakage Behavior of Carbon-Doped GaN

Capacitance transient spectroscopy and dc current–voltage ( I–V ) characterization are employed to analyze charging/discharging effects and transport in 200-nm-thin carbon-doped GaN layers (GaN:C) with a low ( ${N}_{\textsf {C}} = \textsf {10}^{\textsf {18}}$ cm $^{-\textsf {3}}$ ) and high ( ${N}_{\textsf {C}} = \textsf {10}^{\textsf {19}}$ or ${N}_{\textsf {C}}= \textsf {7}\times \textsf {10}^{\textsf {19}}$ cm $^{-\textsf {3}}$ ) carbon concentration ${N}_{\textsf {C}}$ . The discharging and charging events are found to be governed by transport properties of GaN:C for whole ${N}_{\textsf {C}}$ range. However, distinct temperature behavior has been found as a function of ${N}_{\textsf {C}}$ . In the samples with low ${N}_{\textsf {C}}$ , an Arrhenius-like behavior with an activation energy of 0.8 eV indicates that the hole transport in valence band (VB) is the limiting process and the carrier exchange occurs between VB and the defect level. In contrast, in samples with high ${N}_{\textsf {C}}$ , a non-Arrhenius charging/discharging behavior with exp( aT )-dependence ( ${a}$ being a constant) in a wide temperature range (150–560 K) indicates that the transport is governed by defect bands (DBs) where the carrier exchange occurs between DBs and the carbon defect level. For samples with ${N}_{\textsf {C}} \ge \textsf {10}^{\textsf {19}}$ cm $^{-\textsf {3}}$ , the large charge accumulation in GaN:C produces a large energy barrier to prevent electron injection from n-GaN to GaN:C, thus making GaN:C blocking. This is in contrast to samples with ${N}_{\textsf {C}} = \textsf {10}^{\textsf {18}}$ cm $^{-\textsf {3}}$ where the barrier is low, rendering thus the bilayer leaky. Detailed physical models for carrier capture and emission processes and carrier transport are provided for both cases. The developed knowledge is important for understanding the role of growth parameters such as ${N}_{\textsf {C}}$ and dislocation densities, as well as for reliability testing and defect analysis.

Structural, magnetic and electric properties of pure, Pr, Ce doped and Ce–Mn co-doped bismuth ferrites

Sol–gel synthesized pure, Pr, Ce doped and Ce–Mn co-doped BiFeO3 samples show that doping and co-doping increases the symmetry with suppressed secondary phases. Microstructural investigation indicated particles and highly dense rectangular grains images with different sizes and shapes. M–H and P–E loop study shows that magnetic and ferroelectric properties are strongly dependent on doping and co-doping. Frequency dependent dielectric properties of samples concluded improvement in various parameters. Leakage current study shows that there is decrease in leakage behavior for Pr, Ce doped samples but increment for Ce–Mn co-doped BiFeO3 for applied field.

Annealing and Impurity Effects in Co Thin Films for MOL Contact and BEOL Metallization

PVD, CVD, and electrodeposited blanket Co films were studied using SEM, XRD, XPS, SIMS, open circuit wet etching in DHF, and linear sweep amperometry. All Co films exhibit (002) hexagonal close packed preferred orientation that is enhanced upon anneal, except for the PVD Co, whose texture is unchanged. Although as-deposited film resistivity varies significantly, post-anneal resistivity values for all films are similar (∼ 6–8 μΩ cm). As-deposited PVD Co and Co plated from an acidic sulfate chemistry are relatively pure, dissolve slowly in DHF, and show modest changes upon annealing. As-deposited CVD Co has high levels of impurities and correspondingly high DHF etch rates; annealing significantly reduces impurities and improves DHF etch resistance. Increased Co and reduced O at the surface is observed by XPS upon anneal for all films except for PVD Co. The role of Co oxidation in interconnect resistance and leakage behavior is assessed by employing different Co dielectric cap processes.

Effects of Hydrogen Treatment in Barrier on the Electroluminescence of Green InGaN/GaN Single-Quantum-Well Light-Emitting Diodes with V-Shaped Pits Grown on Si Substrates**Supported by the National Key R&D Program of China under Grant Nos 2016YFB0400600 and 2016YFB0400601, the State Key Program of the National Natural Science Foundation of China under Grant No 61334001, the National Natural Science Foundation of China under

Effect of hydrogen (H2) treatment during the GaN barrier growth on the electroluminescence performance of green InGaN/GaN single-quantum-well light-emitting diodes (LEDs) grown on Si substrates is experimentally investigated. We prepare two LED samples with different carrier gas compositions during the growth of GaN barrier. In the H2 free LED, the GaN barrier is grown in full nitrogen (N2) atmosphere. For the other H2 treated LED, a mixture of N2 and H2 was used as the carrier gas. It is observed that V-shaped pits decrease in size after H2 treatment by means of the scanning electron microscope. Due to the fact that the p–n junction interface would be closer to the p-GaN as a result of smaller V-shaped pits, the tunneling barrier for holes to inject into the InGaN quantum well would become thicker after H2 treatment. Hence, the external quantum efficiency of the H2 treated LED is lower compared to the H2 free LED. However, LEDs would exhibit a better leakage behavior after H2 treatment during the GaN barrier growth because of more effective blocking of the threading dislocations as a result of the H2 etching at V-shaped pits.

Growth assessment and scrutinize dielectric reliability of c-axis oriented insulating AlN thin films in MIM structures for microelectronics applications

The present study reports the effect of bottom electrodes (Al, Pt & Ti) on the texture, piezoelectric characteristics, dielectric properties and leakage current behavior of reactive DC magnetron sputtered AlN thin films. X-ray diffraction results revealed that the lattice structure and texture of bottom electrode plays a vital role in c-axis wurtzite phase growth of aluminum nitride (AlN) thin films. A highly (002) oriented c-axis AlN thin films was obtained over Ti as compared to Al and Pt electrodes. The piezoelectric coefficient (d33eff) of these fabricated AlN thin films were measured by piezoresponse force microscopy to evaluate their piezoelectric efficiency in resonators. AlN is a good option for passivation purpose in microelectronic devices because of high chemical stability and excellent dielectric properties. Therefore, the dielectric reliability of AlN thin films is very crucial. Among all structures, AlN/Ti structure exhibits a highest dielectric constant (εr) ∼ 8.63 at 1 MHz. This work also provided a comprehensive study of leakage current conduction mechanism with electric field. The leakage behavior depicts that all AlN film endures a transition from ohmic conduction (E < 70 kV/cm) to SCLC conduction (E > 70 kV/cm). In addition, the breakdown characteristic of these fabricated films was studied for deciding the long-term device reliability and life. This study suggests that the electrode engineering of AlN thin films have a potential in devices for electrical and micro-electro-mechanical system (MEMS) applications.

Compact Storage of Radioactive Cesium in Compressed Pellets of Zeolite Polymer Composite Fibers.

To facilitate the safe storage of radioactive Cs, a zeolite–poly(ethersulfone) composite fiber was fabricated to be a compact storage form of radioactive Cs, and an immobilization was investigated with respect to the effects of volume reduction and stability of the fiber’s adsorbent matrix. Using compressed heat treatment at 100–800 °C for a zeolite polymer composite fiber (ZPCF) containing Cs, the fabrication changed its form from a fiber into a pellet, which decreased the matrix volume to be about one-sixth of its original volume. The Cs leakage behavior of the ZPCF matrix was examined in its compact pellet form for non-radioactive Cs and radioactive Cs when different fabrication conditions were carried out in the immobilization. The elution ratio of non-radioactive Cs from the matrix was minimal, at 0.05%, when the ZPCF was compressed with heat treatment at 300 °C. When using radioactive Cs for the compression at below 300 °C, the pellet form also had no elution of the pollutants from the matrix. When the compressed treatment was at 500 °C, the matrix exhibited elution of radioactive Cs to the outside, meaning that the plastic component was burning and decomposed in the pellet. A comparison of ZPCF and natural zeolite indicated that the compressed heating process for ZPCF was useful in a less-volume-immobilized form of the compact adsorbent for radioactive Cs storage.

Leakage Models for High-Level Power Estimation

Leakage currents are one major concern when designing recent CMOS devices, making design for leakage at all stages of the design process mandatory. Early leakage optimization requires early leakage prediction, and for electronic system level design, this means estimation capabilities at register transfer (RT) level or above. Existing models are very accurate, but slow [transistor level such as Berkeley Simulator (BSIM)], or the slightly faster gate level models (such as the Liberty library), disregard relevant parameters. We present RT level leakage macro models, which are faster than recent gate level models, while preserving the accuracy of the transistor level models to a great extent. An estimation framework is proposed, describing the subthreshold, gate, and junction leakage of recent technology devices. The models are characterized using BSIM compact models and a Monte Carlo process variation description. Each varying BSIM parameter can be described. As an example of use, channel length, oxide thickness, and channel doping are regarded together with the temperature, supply voltage and body voltage. The final macro model needs less than a hundred parameters to capture the leakage behavior of an entire RT component and is still analytically describing the dependence to the process parameters. Compared to SPICE + BSIM, a model prediction is computed up to a hundred times faster for large RT components, and is, depending on the analyzed technology, within 2.1% (for 16-nm LP)–6.8% (for 65-nm bulk) deviation over a wide range of operating conditions and process variation settings.

Leakage evolution and atomic-scale changes in Pd-based membranes induced by long-term hydrogen permeation

The long-term operation of a ceramic-supported 5 μm-thick Pd membrane at 450 °C and 27 bar with a feed representing steam-methane-reforming conditions has been monitored over a period of 100 days. Subsequently, a thorough characterisation of the exposed membrane has been performed to investigate leakage behavior and microstructural changes to the membrane occurring during the long-term membrane operation. Initially, a H2 permeance of 2.8·10−4 mol m−2 s−1 Pa−0.5 and a H2 permeate purity of 99.8% have been obtained. During continuous operation over 100 days, however, a slow but gradual decrease in H2 purity has been observed at a close-to-constant H2 permeance. Post-process leakage behavior has indicated that the increase in leakage is mainly caused by an increase in the Knudsen flow contribution, reflecting an increase in either the amount or size of nano-sized defects. A rising water test shows that these nano-sized defects are almost evenly distributed over the membrane length. Observation of the membrane cross-section revealed the formation of cavities that grew to sizes up to tens of nanometers, as a result of molecular recombination of hydrogen at low-energy sites such as dislocation walls and high-angle grain boundaries. The spherical shapes of the bubbles point to these being energetically favorable, which may be consistent with comparably high surface tensions. Therefore, the cavities observed are believed to be filled with hydrogen and stabilized by an internal pressure, that effectively counteracts the strong effect of surface energy at these small scales. The cavities may represent the origin of pinhole formation, and the atomic mechanisms behind the observed behavior are discussed and directions for enhancing the microstructural stability of Pd-based membranes are pointed out.

Preparation and characterization of Al2O3 film deposited by RF sputtering and plasma enhanced atomic layer deposition

In this paper, the authors have investigated the structural and electrical properties of thin film of Al2O3 deposited by radio-frequency sputtering and plasma enhanced atomic layer deposition (PEALD) technique. Different deposition and process parameters for the sputtered and PEALD Al2O3 films were chosen to investigate their effect on the structural and electrical characteristics of the film. X-ray diffraction result shows the dominant peak of Al2O3 in both the cases at 2θ = 56° indicating (312) film orientation. Multiple angle analysis of sputtered and PEALD Al2O3 film shows a refractive index in the range of 1.70–1.74 and 1.65–1.69, respectively. Electrical characteristics indicate that the device fabricated by PEALD and annealed at 425 °C shows the positive flatband voltage of 3.5 V and improved leakage behavior as compared to the film deposited by sputtering.

Pulsed-Laser Deposited 35 Bi(Mg1/2Ti1/2)O3-65 PbTiO3 Thin Films-Part II: Influence of A-Site Deficiency and Thickness Scaling on Electric Properties.

35 Bi(Mg1/2Ti1/2)O3-65 PbTiO3 (35 BiMT-65 PT) thin films with varying levels of A-site deficiency were investigated as a potential candidate for high-temperature nonvolatile ferroelectric memories. PbTiO3 seed layers utilized to nucleate the perovskite phase in A-site deficient films induced a thickness dependence to the ferroelectric hysteresis and dielectric permittivity. Adjusting for this, the dielectric response of the 35 BiMT-65 PT films is $\approx 960$ . The maximum dielectric permittivity was 430 °C at 1 MHz for A-site deficient films. The transition temperature is independent of film thickness to 85 nm. Tan( $\delta$ ) remains less than 15% at 1 MHz regardless of film thickness and temperature up to 585 °C. High-temperature polarization-electric field hysteresis measurements show charge injection with increasing temperature, while positive-up-negative-down measurements show little temperature dependence of $P_{r}$ up to temperatures of 200 °C. Poole-Frenkel emission dominated the high field leakage behavior. The refractive index measured by ellipsometry is 2.58 at 633 nm. All samples show significant retention loss. As the stoichiometry improves, retention improves such that >40% of the initial $\Delta P$ is retained over $\approx 280$ min.

A fractional-order model-based battery external short circuit fault diagnosis approach for all-climate electric vehicles application

Abstract: The impact of SOC and temperature on external short circuit (ESC) faults characteristics of lithium-ion batteries, including the current and voltage variation and temperature increase, are analyzed. A fractional-order model (FOM) and a first-order RC model are both employed to describe the electrical behavior of the battery cells with the ESC fault. While the model parameters are identified by the genetic algorithm (GA). A comparison study is made on the prediction accuracy for the two models. An effective classification method based on a random forests (RF) model is proposed to recognize the electrolyte leakage behavior that occurs during the ESC fault experiments. Based on the above efforts, the three steps model-based diagnosis algorithm for identifying the ESC fault and even electrolyte leakage of the battery in real-time is proposed. Two indicators of the root mean square error (RMSE) of battery predicting voltage are applied to diagnose for the ESC fault only and ESC-leakage merged fault. The result of the leakage condition is obtained by a pre-trained RF classifier to confirm the leakage detection result based on the RMSE indicator. Several cases are verified that all the ESC cells can be diagnosed efficiently.

The structural and electrical properties modulated by excessive Ti substitution in SrTiO3 films

Ti-rich nonstoichiometric SrTiO3 (STO) films are fabricated on (111) Pt/Ti/SiO2/Si substrates by metal organic deposition. X-ray diffraction reveals the structure of the samples. The effect of nonstoichiometry on the electrical properties of the STO films is investigated by leakage current measurements and dielectric and ferroelectric characterizations. They reveal that the direct current (dc) leakage behavior is greatly improved with increasing Ti content, while the Ti = 1.1 and 1.2 samples show an obvious dielectric relaxation behavior related to the variable valence of the excess Ti ions. More importantly, the nonstoichiometric STO exhibits the room temperature ferroelectric polarization that can be explained mainly by the Ti antisitelike defects and the change of crystal lattice structure of the sample.

Experimental study of supercritical CO2 leakage behavior from pressurized vessels

The accidental leakage is one of the main risks in supercritical CO2 transportation and storage system. A new experimental facility was built to study the leakage behavior of supercritical CO2 flow. The leakage flow and jet flow behaviors of supercritical CO2 from pressurized vessels were experimentally investigated. The upstream temperature was examined ranging from 34.9 to 100.5 °C. The effects of upstream pressure were tested ranging from 8.1 to 11.0 MPa. The effects of nozzle geometry structure were tested by using six nozzles with length-diameter ratio (L/D) ranging from 1 to 15. The supercritical CO2 leakage mass flow rate decreases with the increase of upstream temperature and L/D, and increases with the increase of upstream pressure. An empirical correlation with geometric and thermal parameters is developed based on a large amount of experimental data. The experimental data of leakage flow and empirical correlation could be used for safety assessment and theoretical model validation.

Evaluation and experimental study on the sealant behaviour of double gaskets for shield tunnel lining

As waterproof joints are essential for shield tunnel segmental lining, double gaskets have been adopted for certain tunnel segments with high ground water pressure to prevent water leakage. To investigate the leakage behaviour of double gaskets in shield tunnel lining with joint opening and offset combination, mechanical and leakage tests were conducted on double gaskets subjected to water pressure. The linings are made of bolted and precast concrete with double gaskets, and the two gaskets are different sizes, but both have open bases. The mechanical test results revealed that three distinct phases are observable in the gasket load deformation curve, due to the process of gasket compression. Inappropriate design parameters for the gasket can result in the segment spalling around the gasket groove in field. In this study, improved parameters, including the diameter of circle hole inside the gasket and the hardness of the gasket, are presented with the goal of preventing segment damage. The experimental sealant test results demonstrated that the joint opening has a significant effect on the gasket leakage capacity: with increasing joint opening, the gasket sealant capacity decreases. The leakage mechanism of the double gaskets is also elucidated.

Experimental evaluation of tritium oxidation efficiency in the room temperature recombiner

To enhance public acceptance of a nuclear fusion reactor, the realization of passive detritiation system is a technical challenge taking hypothetic extraordinary situations occurred in a nuclear fusion facility into consideration. To achieve passive tritium oxidation with a room temperature recombiner (RTR), the hydrophobic platinum catalyst has been realized and data on kinetics have been accumulated. Since the efficiency of hydrogen oxidation at room temperature decreases with a decrease in hydrogen concentration, the worst condition of the process gas for RTR is the lowest hydrogen in the process gas. To overcome this condition, we have proposed to add hydrogen intentionally to be 100 ppm at the inlet of RTR. In this study, the dynamic behavior of a tritium leakage in a 12 m3 simulated room and the detritiation with a RTR was demonstrated to confirm the effectiveness of our proposal considering the worst condition for RTR. Initial tritium concentration in the containment was 1.0 GBq/m3. The flow rate was set to 1.8 Nm3/h. The volume of the hydrophobic platinum catalyst was 1000 cm3. Tritium concentration in the containment smoothly decreased one order magnitude after processing for 900 min. We obtained a prospect that a sufficient hydrogen conversion rate can be secured by adding hydrogen of about 100 ppm. From the kinetics point of view, the required amount of catalyst for a RTR is estimated to be three times that for a heated reactor at 473 K in order to obtain the same conversion efficiency of tritium.

Study of true-remanent polarization using remanent hysteresis task and resistive leakage analysis in ferroelectric 0.64Pb(Mg1/3Nb2/3)O3-0.36PbTiO3 ceramics

The conventionally reported value of remanent polarization (Pr) contains contribution from non-remanent components which are not usable for memory device applications. This report presents techniques which extract the true-remanent (intrinsic) component of polarization after eliminating the non-remanent component in ferroelectric ceramics. For this, “remanent hysteresis task” and “positive-up-negative-down technique” were performed which utilized the switchable properties of polarizations to nullify the contributions from the non-remanent (non-switchable) components. The report also addresses the time-dependent leakage behavior of the ceramics focusing on the presence of resistive leakage (a time-dependent parameter) present in the ceramics. The techniques presented here are especially useful for polycrystalline ceramics where leakage current leads to an erroneous estimation of Pr.

Comprehensive investigation of leakage problems for concrete gravity dams with penetrating cracks based on detection and monitoring data: A case study

The leakage amount is an important indicator evaluating the seepage behavior of a dam. Due to the complex behavior, crack development judgment and leakage behavior identification for concrete gravity dams remain a challenging task. The paper is concerned with comprehensive investigation of leakage problems for concrete gravity dams with penetrating cracks. A case study on Shimantan Reservoir Dam was taken to examine the utilization of the comprehensive investigation method. Deficiency investigations were undertaken to identify the nature and sources of defects responsible for the serious leakage. Based on the information acquired from field visual inspections and ground-penetrating radar tests, it is apparent that several transverse cracks penetrate the dam crest and propagate downward into the dam body. The results of the remedial grouting, X-ray diffraction analyses and water injection tests reflect the appearance of penetrating leakage paths in the dam body. Subsequently, 2 behavior models including the special hydrostatic-seasonal-time model and the inverse analysis model were conducted to distinguish the contribution of penetrating cracks to leakage amount. The special hydrostatic-seasonal-time model was modified to address the influence of leakage flow in real microcracks in concrete dams based on the Navier–Stokes equation. The result shows that the proposed models provide an acceptable accuracy in analyzing leakage monitoring data for gravity dams with penetrating cracks. Leakage flow in penetrating cracks plays a dominant role in the dam seepage field. The execution flow in this paper could be readily employed in investigations of similar problems of concrete dams.

Total Dose Effects and Bias Instabilities of (NH4)2S Passivated Ge MOS Capacitors With Hf&lt;italic&gt;x&lt;/italic&gt;Zr1–&lt;italic&gt;x&lt;/italic&gt;O&lt;italic&gt;y&lt;/italic&gt;Thin Films

The effects of biased irradiation on Ge MOS capacitors with Hf x Zr1– x O y (0.43 x $^{137} \gamma $ -ray radiation source with 0.5 or –0.5 V gate bias. Prior to irradiation exposure, leakage behavior and bias-instability of Hf x Zr1– x O y films were also examined. Gate leakage current density increases with the increasing of Zr composition in gate oxide. In addition, Zr-containing dielectrics under positive bias (PB) exhibited more oxide negative trapped charges than that of HfO2, which suggested that the oxygen-vacancy concentration in Hf x Zr1– x O y was increased by the addition of Zr. Larger flat-band voltage shifts ( $\Delta V_{\mathrm {FB}})$ were extracted under positive biased irradiation than the bias only results. The results indicate that radiation-induced interface traps ( $\Delta N_{\mathrm {it}})$ are the dominant factor for $\Delta V_{\mathrm {FB}}$ in HfO2 thin films, whereas the radiation response for Zr-containing dielectrics under PB was mainly due to oxide traps. Under negative biased irradiation, $\Delta V_{\mathrm {FB}}$ was attributed to the combined effect of the net oxide trapped charges and the passivation of Ge dangling bonds at the Ge/high-k interface. Additionally, both bias-induced and radiation-induced charge trapping have a crucial effect on radiation response of Hf x Zr1– x O y at each dose level. Hf x Zr1– x O y is identified as a promising gate dielectric for advanced complementary metal–oxide–semiconductor technologies.

Radicalization patterns and modes of attack planning and preparation among lone-actor terrorists: an exploratory analysis

ABSTRACTThis article explores the link between radicalization patterns and modes of attack planning and preparation among lone-actor terrorists. Building on theorized patterns of lone-actor radicalization, we discuss and compare their modes of pre-attack behavior, including target and weapon choice, observance of operational security measures, likeliness of engaging in leakage behavior, and the overall amount of time devoted to these activities. This exploratory study builds upon a dataset of thirty-three lone-actor terrorist cases in North-America and Europe between 1986 and 2015. The analysis suggests that specific patterns of radicalization are linked to systematic differences in modes of attack planning and preparation. The results provide insights into the heterogeneity of terrorist involvement and tentatively suggest the potential importance for law-enforcement agencies in using case-specific knowledge on radicalization patterns to inform forecasts of likely pre-attack behaviors.

DLTS Analysis and Interface Engineering of Solution Route Fabricated Zirconia Based MIS Devices Using Plasma Treatment

In this work, we have fabricated low-temperature sol–gel spin-coated and oxygen (O2) plasma treated ZrO2 thin film-based metal–insulator–semiconductor devices. To understand the impact of plasma treatment on the Si/ZrO2 interface, deep level transient spectroscopy measurements were performed. It is reported that the interface state density (D it) comes down to 7.1 × 1010 eV−1 cm−2 from 4 × 1011 eV−1 cm−2, after plasma treatment. The reduction in D it is around five times and can be attributed to the passivation of oxygen vacancies near the Si/ZrO2 interface, as they try to relocate near the interface. The energy level position (E T) of interfacial traps is estimated to be 0.36 eV below the conduction band edge. The untreated ZrO2 film displayed poor leakage behavior due to the presence of several traps within the film and at the interface; O2 plasma treated films show improved leakage current density as they have been reduced from 5.4 × 10−8 A/cm2 to 1.98 × 10−9 A/cm2 for gate injection mode and 6.4 × 10−8 A/cm2 to 6.3 × 10−10 A/cm2 for substrate injection mode at 1 V. Hence, we suggest that plasma treatment might be useful in future device fabrication technology.