Leakage Current Characteristics Research Articles

Effects of ion irradiation induced phase transformations and oxygen vacancies on the leakage current characteristics of HfO2 thin films deposited on GaAs

Abstract We report on the ion-induced phase transformations, defect dynamics related to oxygen vacancies and the resulting leakage current characteristics of RF sputtered HfO2 thin films grown on GaAs. A systematic growth of HfO2 grains and Ion prompted phase transformations of HfO2 to crystalline phases such as monoclinic and tetragonal/orthorhombic (mixed phase) in otherwise amorphous HfO2 thin films have been observed after irradiation. At lower fluences, Ion induced enhancement in the dielectric properties of HfO2 thin films resulted in a reduction in the leakage current, whereas ion prompted defect formation at higher fluences caused a systematic increase in the leakage current density. Further, the effects of Poole-Frenkel (PF) tunneling and Fowler-Nordheim (FN) tunneling on the leakage current have also been investigated. These mechanisms showed the existence of impurities in the as-grown films. Photoluminescence (PL) study suggests the variation in the defect configuration related to O-vacancies and slight shift in the peak positions due to SHI irradiation are responsible for the observed changes in electrical characteristics. This study offers worthwhile information for considering the effects of electronic excitation prompted defect annealing or defect creation on the performance of HfO2/GaAs based photonic and optoelectronic devices, particularly, when such devices are operated in a radiation harsh environment.

Reliability research of thyristors for HVDC transmission system

The long-term operation performance of HVDC transmission systems is significantly influenced by the reliability of thyristors. However, the current reliability research of thyristors is mainly based on the leakage current and there is no comprehensive degradation characteristics of thyristors. In this article, the degradation characteristics of thyristors under voltage and temperature accelerated ageing tests are obtained, including the reverse recovery characteristic, on-state characteristic, blocking characteristic and gate characteristic. The reverse recovery characteristic obviously degrades under the voltage accelerated ageing tests. The reverse recovery charge and reverse recovery time decrease by over 10% after the tests. Seven thyristors operating for a certain number of years from two HVDC stations are tested, and the results verify the thyristor degradation characteristics obtained from the ageing tests. Moreover, the mechanisms of the leakage current and reverse recovery characteristic are analyzed in detail.

Silica conversion of polysilazanes by low-temperature plasma jet generated from Ar and water-vapor mixed gas

Perhydropolysilazane (PHPS), which contains no organic catalyst, chemically reacts with H2O in the atmosphere by heating it at 450 °C for more than 1 h to turn it into a SiO2 film. If silica conversion can be achieved at temperatures below 100 °C, which plastics can withstand, it may be applicable to a wide range of applications, such as flexible electronics. Here, we report a technique for forming SiO2 films with leakage current characteristics very close to those of thermally oxidized (THOX) films that works at a very low temperature of 52 °C with high speed. Using a 9-kV, 30-kHz power supply, a low-temperature plasma jet containing a gas mixture of Ar and water vapor irradiated an 8 nm thick PHPS thin film, inducing silica conversion at a maximum substrate temperature of 52 °C. The current density-electric field strength (J-E) characteristics of metal oxide semiconductor capacitors fabricated with this SiO2 film showed characteristics very close to those of THOX films. In addition, the mechanism of silica conversion of PHPS through low-temperature plasma jet irradiation using this gas mixture was clarified in real-time FT-IR measurements.

Leakage Current and Breakdown Characteristics of Isolation in Gallium Nitride Lateral Power Devices

Leakage Current and Breakdown Characteristics of Isolation in Gallium Nitride Lateral Power Devices

Structural, electrical, leakage current, and magnetic characteristics of double perovskite Nd2NiTiO6

AbstractThis study investigates the structural, electrical, leakage current, and magnetic characteristics of the double perovskite material Nd2NiTiO6 synthesized through the sol–gel citrate auto‐ignition method. The Rietveld refinement of the X‐ray diffraction patterns confirmed a monoclinic symmetry (space group P21/n) with an ordered arrangement of alternate NiO6 and TiO6 octahedra. Impedance spectroscopic analysis exhibited the material's non–Debye‐type relaxation mechanism and semi‐conductive nature. AC conduction analysis revealed that the conduction of charge carriers occurs via the nonoverlapping small polaron hopping mechanism, consistent with Mott's variable range hopping model. Temperature‐ and frequency‐dependent dielectric measurements were interpreted using the Maxwell–Wagner interfacial polarization model. The analysis of thermal‐ and field‐dependent leakage currents established that conduction is ohmic, which the Schottky barrier model explains. Studies on magnetization ruled out the presence of magnetic ordering connected to indirect interaction between Ni2+ ions via Ti4+ ions and the rare‐earth cation (Nd3+) moment.

A comprehensive study of gate-induced drain leakage current and electrical characteristics in nanosheet field-effect transistors due to variation in structural parameters and ambient temperature

Abstract IIn this paper, two substrate optimization approaches of triple stacked Nanosheet FET (SNSHFET), namely optimization of buried oxide and selective deposition of punch through stopper (PTS) substrate, have been examined and simulations have been carried out using Technology Computer-Aided (TCAD) software. A comprehensive study of leakage current and key electrical characteristics (I¬ON, VT, SS, DIBL) have also been extracted based on variation in temperature from 298 K to 450 K, sheet width, fin pitch, substrate width, and source/drain doping, as well as different substrates. When the ambient temperature of SNSHFET is varied from 298 K to 450 K, the gate-induced drain leakage (GIDL) current increases and degrades the VT and ION/IOFF ratio. GIDL current also increases with increased doping of the source and drain. Also, the impact of ultra-thin body substrate in SNSHFET is studied for the reduction in GIDL current and optimization in the performance. It is observed that a reduction in the substrate width and the nanosheet width decreases the GIDL current, while variation in Inter-fin pitch has no significant impact on the GIDL current and other electrical characteristics. The band-to-band tunneling rate and electric field profiles are observed at the channel-drain and gate-substrate overlap region for understanding the physical insights of leakage current in the SNSHFET. This work also answers the dependency of GIDL current on the gate and drain voltage supply respectively. In addition to that, how GIDL current responds to the variation in the source-drain doping and with different PTS doping has been explained. The 3 nm-based SNSHFET is designed and its electrical and GIDL characteristics are compared with novel devices like Forksheet FET and Complementary FET.

Low-voltage organic field-effect transistors by using solution-processable high-κ inorganic-polymer hybrid dielectrics

Organic field-effect transistors (OFETs) incorporating hybrid high-κ inorganic Al2O3 and polymer dielectrics, including polyvinyl alcohol (PVA), polystyrene (PS), or polymethyl methacrylate (PMMA), through solution-processing techniques were fabricated. The analyses revealed that the high surface energy and hydrophilicity property of Al2O3 and PVA, and the relatively hydrophobic property of PS surface, hindered the performance of corresponding OFETs. The Al2O3/PMMA-based OFET achieved the optimized performance, with a threshold voltage of −2.7 V, a hole carrier mobility of 0.056 cm2/Vs, and a current on/off ratio of 1.0 × 104 at a low operating voltage of −5 V. Through analyzing the characteristics of leakage current, capacitance, contact resistance, and trap density of OFETs, we found that the PMMA-engaged films possessed the optimized electrical properties. The introduction of PMMA eliminated the interfacial trapping, thereby lowering the threshold voltage and enhancing the performance of the device. The COMSOL Multiphysics simulation was conducted to confirm the physical mechanism. The strategy of utilizing Al2O3/PMMA hybrid dielectric could simultaneously ensure the low operating voltage and good performance of OFET, while guaranteeing the low leakage current by the thick PMMA.

Parametric Analysis of Indium Gallium Arsenide Wafer-based Thin Body (5 nm) Double-gate MOSFETs for Hybrid RF Applications.

The electrical behavior of a high-performance Indium Gallium Arsenide (In- GaAs) wafer-based n-type Double-Gate (DG) MOSFET with a gate length (LG1= LG2) of 2 nm was analyzed. The relationship of channel length, gate length, top and bottom gate oxide layer thickness, a gate oxide material, and the rectangular wafer with upgraded structural characteristics and the parameters, such as switch current ratio (ION/IOFF) and transconductance (Gm) was analyzed for hybrid RF applications. This work was carried out at 300 K utilizing a Non-Equilibrium Green Function (NEGF) mechanism for the proposed DG MOSFET architecture with La2O3 (EOT=1 nm) as gate dielectric oxide and source-drain device length (LSD) of 45 nm. It resulted in a maximum drain current (IDmax) of 4.52 mA, where the drain-source voltage (VDS) varied between 0 V and 0.5 V at the fixed gate to source voltage (VGS) = 0.5 V. The ON current(ION), leakage current (IOFF), and (ION/IOFF) switching current ratios of 1.56 mA, 8.49Í10-6 μA, and 18.3Í107 μA were obtained when the gate to source voltage (VGS) varied between 0 and 0.5 V at fixed drain-source voltage (VDS)=0.5V. The simulated result showed the values of maximum current density (Jmax), one and twodimensional electron density (N1D and N2D), electron mobility (μn), transconductance (Gm), and Subthreshold Slope (SS) are 52.4 μA/m2, 3.6Í107 cm-1, 11.36Í1012 cm-2, 1417 cm2V-1S-1, 3140 μS/μm, and 178 mV/dec, respectively. The Fermi-Dirac statistics were employed to limit the charge distribution of holes and electrons at a semiconductor-insulator interface. The flat-band voltage (VFB) of - 0.45 V for the fixed threshold voltage greatly impacted the breakdown voltage. The results were obtained by applying carriers to the channels with the (001) axis perpendicular to the gate oxide. The sub-band energy profile and electron density were well implemented and derived using the Non-Equilibrium Green's Function (NEGF) formalism. Further, a few advantages of the proposed heterostructure-based DG MOSFET structure over the other structures were observed. This proposed patent design, with a reduction in the leakage current characteristics, is mainly suitable for advanced Silicon-based solid-state CMOS devices, Microelectronics, Nanotechnologies, and future-generation device applications.

Combined effect of total ionizing dose and electromagnetic pulse on MOSFET devices

Theoretical and experimental research on the combined effect of total ionizing dose (TID) and electromagnetic pulses (EMP) is helpful to develop hardening techniques for semiconductor devices. In this work, a numeric model for the comprehension of the combined effect of TID and EMP on MOSFET devices is developed with the semiconductor device simulation software TCAD. Simulation results show that the NMOS and PMOS devices will exhibit more severe leakage current increase and sub-threshold characteristics degradation in the combined environment. In addition, the potential influence of doping concentration and gate length on the performance of the MOSFET in the combined environment is discussed.

Stabilization of Morphotropic Phase Boundary in Hafnia via Microwave Low‐Temperature Crystallization Process for Next‐Generation Dynamic Random Access Memory Technology

The morphotropic phase boundary (MPB), which arises from the combination of antiferroelectric and ferroelectric phases, demonstrates the highest dielectric constant (κ) compared to other phases. This emphasizes its potential as a leading contender for dielectric films in future dynamic random access memory (DRAM) capacitors. MPB‐based high‐κ materials using hafnia have shown a trade‐off between equivalent oxide thickness (EOT) and leakage current density (Jleak) when the crystallization temperature increases with scaling the thickness. Herein, a microwave annealing (MWA) method that can achieve low‐temperature crystallization below 350 °C is employed. The purpose of this method is to mitigate the trade‐off relationships and achieve the strict criteria of current DRAM capacitors. These criteria include low EOT (less than 4 Å) and Jleak (less than 10−7 A cm−2 at 0.8 V) characteristics. The MWA is capable of relatively low‐temperature annealing by supplying energy to the films through both thermal energy and dipole vibration energy. As a result, a record‐low EOT of 3.76 Å and a low leakage current characteristic of 4.2 × 10−8 A cm−2 at 0.8 V are achieved concurrently. It is confident that the research can be important in addressing the challenges associated with reducing the size of next‐generation DRAM capacitors.

Recess-free thin-barrier AlGaN/GaN Schottky barrier diodes with ultra-low leakage current: Experiment and simulation study

In GaN Schottky barrier diodes (SBD), there is a trade-off between the turn-on voltage and the leakage current. In this study, recess-free 4 nm-thin-barrier AlGaN/GaN SBDs with minimal leakage current as well as excellent turn-on voltage homogeneity are developed, which enable better electrical control to pinch off the 2DEG channel under the anode region and avoids trap introduced in the barrier etching process. In detail, the effect of reverse stress on the SBD performance is initially explored by using differential conductance, and then, the anode-to-cathode distances and temperatures dependence of SBDs output characteristics are systematically studied. The fabricated thin-barrier GaN SBDs show a turn-on voltage of ∼0.75 V and a low level leakage current of 9.66 × 10−10 (1.91 × 10−8) A/mm at 300 (423) K, which is among the lowest reported values at the comparable reverse bias voltage and temperature. Moreover, structure parameters of the thin-barrier AlGaN/GaN SBD are systematically modeled and optimized by the TCAD simulations, including anode metal work function, Al mole fraction, the anode-to-cathode distance, and slanted anode angle. The introduction of slanted anode is found to have significant effect on the improvement of reverse breakdown voltage and leakage current characteristics.

Research on Leakage Current Waveform Spectrum Characteristics of Artificial Pollution Composite Insulator

In order to know about the change features of leakage current during the pollution flashover process of composite insulators, the study of the pollution flashover test on composite insulator under the pollutional condition is presented in the artificial fog cabinet. The characteristics of leakage current waveforms in time-domain and frequency-domain are measured and analyzed during the test. The analysis results show that there is a strong correlation among the fundamental harmonic, the third harmonic and fifth harmonic. The characteristics of leakage current spectrum are represented by the maximum value of leakage current (Im), total harmonic distortion (THD), and phase difference of fundamental leakage current (θ). During a near-flash event, the leakage current exhibits high amplitude, low harmonic content, and small phase difference between the fundamental leakage current and voltage. The research findings provide a basis for establishing a pollution flash warning system based on leakage current characteristic quantities.

Characteristics study of heterojunction III-nitride/β-Ga2O3 nano-HEMT for THz applications

In this research study, a recessed gate III-Nitride high electron mobility transistor (HEMT) grown on a lattice matched β-Ga2O3 substrate is designed. This research investigation aims to enhance DC and RF performance of AlGaN/GaN HEMT, and minimize the short-channel effects by incorporating an AlGaN back layer and field plate technique, which can enhances electron confinement in two-dimensional electron gas (2DEG). A precise comparison analysis is done on the proposed HEMT’s input characteristics, output characteristics, leakage current characteristics, breakdown voltage properties, and RF behaviour in presence and absence of AlGaN back layer in regards to field plate configuration. The inclusion of back barrier aids in raising the level of conduction band, which reduces leakage loss beneath the buffer, and aids in keeping the 2DEG to be confined to narrow channel. Furthermore, the field plate design offers an essential electric field drift between gate and drain, resulting to enhanced breakdown voltage characteristics.

Energy storage properties influenced by relaxor ferroelectric properties dependent on the growth direction of epitaxial Bi2SiO5 thin films

Ferroelectric Bi2SiO5 (BSO) thin films were deposited by pulsed laser deposition on Nb-doped (100), (110) and (111) SrTiO3 (Nb:STO) substrates, resulting in (001)-, (113)- and (204)-oriented epitaxial films. Due to the crystallinity of BSO, in which the Bi2O2 layers are formed perpendicular to the c-axis direction, the (001)-oriented epitaxial BSO thin film showed the lowest remanent polarization and the best leakage current characteristics. On the other hand, the (113)- and (204)-oriented films showed an increase in remanent polarization due to the improvement of a-oriented crystallinity. Through experiments using vertical and lateral piezoresponse force microscopy, it has been confirmed that the distribution of in-plane-oriented domains reducing remanent polarization decreases in the order of (001)-, (113)- and (204)-oriented epitaxial BSO thin films. The epitaxial BSO thin films that exhibit ferroelectric hysteresis loops similar to the relaxor ferroelectric thin films tended to have improved energy storage characteristics as a result of improved remanent polarization and saturation polarization. In particular, the (113)-oriented epitaxial BSO thin film showed a high recoverable energy density of about 41.6 J cm−3 and an energy storage efficiency of about 85.6%.

Examining the effects of sintering temperature on double perovskite La2NiTiO6: Analysis of structural, optical, electrical properties, and leakage current characteristics

This study explores the influence of varying sintering temperatures on the structural, optical, electrical, and leakage current features of La2NiTiO6 (LNTO), a double perovskite material synthesized through the citrate auto-ignition method. The X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and energy dispersive X-ray (EDX) analysis were employed to investigate the structure, microstructure, and compositional distribution of the samples. The samples sintered at various temperatures showed the monoclinic structure with space group P21/n and were confirmed by Rietveld's refinement of the XRD patterns. The average grain size increased with higher sintering temperatures, which is consistent with the particle size estimated from the histogram plot of the FE-SEM data. The UV–visible (UV–Vis) spectroscopy showed that the energy band gap decreased as sintering temperatures increased. Impedance spectroscopy analysis revealed non-Debye type relaxation of charge carriers and confirmed the negative temperature coefficient of resistance (NTCR) behavior. Electrical analysis affirmed that the direct current (DC) conductivity is thermally activated, following the Arrhenius equation with an inverse temperature dependency. As the sintering temperature increases, the leakage current density decreases, and the leakage current conforms to the ohmic conduction mechanism.

Designing in-situ carbon-coated mixed phase iron oxides anode coupled with a heteroatom doped porous carbon cathode for lithium-ion capacitors

Lithium-ion capacitors (LICs) are promising devices to balance the space between lithium-ion batteries and supercapacitors by merging the battery-type anode and capacitor-type cathode materials in a single device. This work represents a lithium-ion capacitor containing in-situ carbon coating on mix-phase iron oxide from ferrocene as an anode and heteroatom-doping on porous carbon as the cathode. This type of cathode facilitates better wettability and a good contact area between the electrode and electrolyte, leading to a capacitance of 154 F g−1, retaining 76 % capacitance after 10,000 cycles at 1 A g−1. In contrast, the anode half-cell exhibits 545 mAh g−1 at 1 A g−1 and ∼76 % retention in capacity after 2000 cycles. This is because of nano-structuring and mix-phase iron oxide, allowing a conversion-type reaction to store Li-ions at a high rate, and carbon coating provides electronic conductivity and structural strength upon cycling. The full cell LIC demonstrates energy densities of 91 and 65 Wh kg−1 at power densities of 467 and 9350 W kg−1, respectively. This hybrid device can retain ∼77 % specific capacitance at 1 A g−1 for 5000 cycles. Furthermore, this study analyzes the practical application of LICs by evaluating impedance, self-discharge, and leakage current characteristics.

Effects of Varying Annealing Ambient towards Performance of Ternary GaxCeyOz Passivation Layers for Metal-Oxide-Semiconductor Capacitor

In this work, different annealing ambient (nitrogen-oxygen-nitrogen (N2-O2-N2), forming gas-oxygen-forming gas (FG-O2-FG), and argon-oxygen-argon (Ar-O2-Ar)) were explored to investigate the feasibility of employing the annealed ternary GaxCeyOz passivation layer (PL) for development of Si-based metal-oxide-semiconductor (MOS) capacitors. The impact of nitrogen and/or hydrogen in hindering the growth of silicon dioxide (SiO2) interfacial layer (IL) was quantitatively evaluated. The combination of effects brought by nitrogen attached to oxygen vacancies, nitrogen-silicon bonding, and nitrogen accumulation at the GaxCeyOz/Si interface effectively minimized the formation of SiO2 IL. Consequently, among all the samples, the GaxCeyOz PL annealed in N2-O2-N2 ambient exhibited superior MOS characteristics in terms of low effective oxide charge, slow trap density, interface trap density, and interface state density, which have translated into good leakage current density-electric field characteristics.

Development of a complex strontium bismuth molybdate material: Microstructural, electrical, and leakage current characteristics for storage and electronic device application

In this article, synthesis (solid-state reaction) and characterizations of a complex strontium bismuth molybdate material have been reported. The scanning electron microscopic image suggests the existence of grains of various sizes and shapes that are evenly dispersed, accompanied by small pores. The Maxwell-Wagner dielectric dispersion, relaxation, and transport mechanism have been investigated utilizing dielectric, impedance, and conductivity spectrum within the studied experimental frequency (1 kHz–1 MHz) and temperature (25–500 °C) range. The energy storage efficiency is 56.13 %, calculated by the loop of electric polarization. The results of temperature-dependent resistance suggest that the prepared material can be used for PTC thermistors, sensors, and other related devices. The varistor constants β1 and β2 indicate the presence of non-Ohmic and SCLC conduction mechanisms, which are also suitable for electronic devices.

Novel halogenated cyclopentadienyl hafnium precursor for atomic layer deposition of high-performance HfO2 thin film.

High dielectric constant (high-k) materials play a crucial role in modern electronics, particularly in semiconductor applications such as transistor gate insulators and dielectrics in metal-insulator-metal (MIM) capacitors. However, achieving optimal crystallinity and suppressing interfacial layer formation during deposition processes remain key challenges. To address these challenges, this study introduces a novel approach using atomic layer deposition (ALD) with a new Hf precursor incorporating an iodo ligand. The synthesized precursor, IHf, demonstrates enhanced thermal stability and reactivity, leading to superior film properties. ALD deposition of HfO2 thin films using IHf yields excellent crystallinity and effectively inhibits interfacial layer formation, resulting in enhanced capacitance density and improved leakage current characteristics in MIM capacitors. Notably, IHf-deposited HfO2 films exhibit a significant reduction in leakage current, achieving an equivalent oxide thickness of 1.73 nm at a leakage current density of 7.02 × 10-8 A cm-2 @ +0.8 V. These findings highlight the potential of IHf as a promising precursor for high-performance electronic device fabrication, paving the way for advancements in semiconductor technology.

Energy storage and ferroelectric properties of flexible 1-x(Na0.5Bi0.5TiO3)-xBaTiO3 thin films on Pt/mica substrates

We investigated the energy storage and ferroelectric properties of flexible 1-x(Na0.5Bi0.5TiO3)-xBaTiO3 (NBT) thin films with BaTiO3 (BT) concentrations ranging from 0 to 6 mol% on Pt/mica substrates depending on the BT concentration. The NBT thin films exhibiting preferentially a-oriented crystallinity on the (111) Pt/mica substrates showed improved leakage current characteristics by increasing the BT concentration. In particular, the NBT thin films with zero BT concentration showed a high remanent polarization of about 28.4 μC/cm2. On the other hand, the NBT thin films with a BT concentration of 6 mol% significantly reduced the remanent polarization to about 4.7 μC/cm2 due to the characteristics of the relaxor. As a result, the NBT thin films with a BT concentration of 6 mol% showed a high energy storage efficiency of 89.5 % with a high recoverable energy storage density of 54.3 J/cm3 and a low loss energy density of 6.3 J/cm3.