DC Electrical Characteristics Research Articles

Sm3+-substituted NiZnCd nanoferrites: synthesis, magnetic interactions, and DC electrical resistivity characteristics

Sm3+-substituted NiZnCd nanoferrites: synthesis, magnetic interactions, and DC electrical resistivity characteristics

60Co gamma radiation effects on NPN transistor at cryogenic temperature.

The 60Co gamma radiation effects on the DC electrical characteristics of silicon NPN transistor were studied in the dose range of 100krad to 6Mrad at room temperature (300K) and cryogenic temperature (77K). The measurements were carried out at both 300 and 77K temperature. The electrical characteristics such as Gummel characteristics, excess base current (ΔIB), current gain (hFE), transconductance (gm) and output characteristics were studied in situ as a function of total dose. The results show that there is a considerable degradation in the electrical parameters of the device irradiated both at 300 and 77K as a consequence of increase in excess base current (ΔIB) because of the formation of generation and recombination centers in the emitter-base spacer oxide (SiO2). At cryogenic temperature irradiation, the degradation in electrical characteristics is less because of the physical phenomena such as carrier freezeout effect, decreased recombination rate, reduced charge yield, decreased electron mobility, etc.

Hindered phenolic antioxidant grafting on tailoring the DC electrical characteristics of polypropylene cable insulation

AbstractThe authors focus on the impact of melt‐free radical grafting with hindered phenolic antioxidants (AO3052) on the electrical properties of polypropylene (PP) for DC cable insulation. The DC conductivity, space charge distribution and breakdown characteristic tests of grafting‐modified PP are performed by comparing unmodified PP. The results demonstrate that the grafting of antioxidants can effectively suppress space charge injection, owing to the deeper trap sites at the grafting molecule. The breakdown strength of the grafted PP is significantly enhanced from 30°C to 90°C and especially achieves a 5.3%–6.7% increase after the same DC‐prestressed time at 90°C. The surface electrostatic potential and molecular orbitals of the grafted PP are calculated. Simulation shows that the antioxidant introduces multi‐level local state traps that can effectively trap the injected space charge, thus decreasing the destruction of molecular chains by electrons and increasing the breakdown strength level. In conclusion, antioxidant grafting modification can improve the breakdown characteristics with or without DC prestress, and thus it appears to be promising in the application of PP‐insulated cables.

Colossal permittivity, impedance analysis and electric properties in AlGaN/GaN HEMTs

The electric and dielectric processes of AlGaN/GaN/Si HEMTs produced by molecular beam epitaxy were examined utilizing direct current-voltage, impedance spectroscopy, and DLTS measurements. Using current-voltage measurements, the DC electrical characteristics of AlGaN/GaN/Si HEMTs revealed the self-heating effect. The relaxation dynamics of charge carriers appear to be studied by the conductance mechanism and electric modulus formalisms. Behavior that is frequency dependent has been observed in impedance spectroscopy. Last but not least, DLTS data have demonstrated the existence of electron traps. The prevalence of parasitic effects and conduction mechanisms are remarkably correlated with deep levels.

Exploration of the structural, magnetic, and DC electrical resistivity characteristics of nanoparticles consisting of Sm3+ substituted NiCuZn spinel ferrite

In this study, we investigate the effects of Sm3+ substitution at low concentrations on the structural, electrical, and magnetic properties of ferrite samples. The original composition (Ni0.4Cu0.2Zn0.4Fe2-xSmxO4) was modified with varying values of x (0.00, 0.02, 0.04, 0.06, and 0.08). To achieve this, we employed the sol–gel auto-combustion method. We performed a range of characterizations, including X-ray diffractometry (XRD), field emission scanning electron microscopy (FESEM), Fourier-transform infrared spectroscopy (FTIR), DC electrical resistivity testing, and Vibrating Sample Magnetometer (VSM) analysis. Our XRD analysis confirmed that the ferrite samples exhibited a cubic spinel structure with a well-defined (311) plane peak, indicating high crystallinity and a single-phase composition. The Sm incorporation into NiCuZn ferrite material increases in lattice constant, which lies 8.3954 Å to 8.4287 Å. The crystallite size decreases from 41 to 36 nm. The FESEM micrographs further revealed that the average grain size decreased as the Sm3 + concentration increased. The FTIR spectra analysis successfully incorporated Sm3+ ions into the octahedral sites within the ferrite lattice. We found that pure ferrite (x = 0.00) nanoparticles exhibited the highest saturation magnetization (Ms) value at room temperature, measuring 75 emu/g. As the Sm3+ substitution level increased, we observed a progressive reduction in saturation magnetization (Ms). Notably, the most significant change in DC resistivity occurred at a substitution ratio of x = 0.02, indicating the substantial influence of Sm3+ ions on the activation energy. These magnetic and electrical properties offer valuable insights into applications in various technological fields like magnetic recording media.

Coexistence of synaptic behaviour and negative differential resistance at room temperature in the resistive switching device based on natural indigo molecules

The memory storage and processing capability of human brain is throwing excitement and challenges to create a low power consuming “brain-like functioning device” called neuromorphic device which is the basis of automation and robotics. We demonstrate a robust and highly efficient two-terminal device (Al/Indigo/Al) based on natural indigo molecules to emulate synaptic functionalities for use in neuromorphic applications. The indigo molecules are sourced from plants and are stable at room temperature. Molecules exhibit an optical energy gap of ∼ 1.9 eV evidenced by UV–vis spectroscopy. A detailed analysis of conduction mechanism is performed via dc-electrical characteristics. Consistent negative differential resistance (NDR) is observed, which we attribute to the deep trap states. The analysis shows that conduction is due to the trap-assisted Poole-Frenkel effec. The device maintains an extremely stable high-resistance state (HRS) and low resistance state (LRS) up to 9000 cycles of read – write - erase operation. Further, the essential characteristics such as paired pulse facilitation (PPF) and paired pulse depression (PPD) have been measured on the device. Potentiation (learning) and depression (forgetting) curves follow double exponential with more than 85% of the potentiation/depression occurring in the initial few pulses. Non-linearity (NL) calculations suggest that the device performance can be tuned by carefully choosing the pulse voltage and pulse width such that the nonlinearity factor is reduced. This work clearly indicates an easy approach for the fabrication of natural organic molecule-based artificial synapse that works efficiently at room temperature, as well as the method for selecting measurement parameters to obtain low-power consuming artificial synapse.

NSFET performance optimization through SiGe channel design - A simulation study

In this article, NSFET performances including DC electrical characteristics, analog/RF metrics and NBTI degradation are studied using 3D fully-calibrated TCAD simulation. Through contrastive analysis, it is found that the introduction of SiGe into channel significantly improves the on-state current (Ion), lowers SS and Vth, brings an overall improvement to analog/RF metrics and inhibits NBTI degradation, but deteriorates short channel effects (SCEs). To obtain proper thickness and fraction of SiGe, which can provide better optimization for device performances, further simulations were done for SiGe devices including SiGe cladded channel NSFET (Device A) and full SiGe channel NSFET (Device B). Simulation results show that when the thickness of the SiGe layer is 1 nm and the Ge composition in SiGe is 0.2, the performance of the device is optimal for Device A. Compared with the NSFET with silicon channel, the Ion of Device A is increased by 150.2 %, the SS is increased by 9.9 %, the fmax is increased by 20.8 %, and the NBTI degradation is reduced by 28.1 %. For Device B compared with NSFET with silicon channel, when the Ge composition in SiGe is 0.2, the performance is optimized as: 3534.4 % improvement in Ion, 3.2 % in SS, 1095.1 % in fmax, and 26.3 % in NBTI degradation.

The effect of electrical stress and thermal annealing on swift heavy ion irradiated SiGe HBTs

The nano-engineered silicon–germanium heterojunction bipolar transistors (SiGe HBTs) were irradiated with 100 MeV phosphorous ions up to a high total dose of 100 Mrad. The irradiated SiGe HBTs were subjected to mixed mode (MM) electrical stress and isochronal annealing. The DC electrical characteristics were studied for ion irradiated, electrically stressed and thermally annealed SiGe HBTs. The important parameters such as base current (IB), current gain (hFE) and output characteristics of the irradiated SiGe HBTs were significantly degraded after 100 Mrad of the total dose. This is due to high energy ion induced damages in Emitter-Base (E-B) and Shallow Trench Isolation (STI) oxides. A significant recovery in device parameters was observed after both MM stress and isochronal annealing. The recovery in electrical characteristics of the irradiated SiGe HBTs is mainly due to the raise in the junction temperature and de-trapping of trapped charges.

Effect of Si-rich SiXNY multilayer passivation material on the DC electrical characteristics of AlGaN/GaN HEMTs

Effect of Si-rich SiXNY multilayer passivation material on the DC electrical characteristics of AlGaN/GaN HEMTs

Facile synthesis of polystyrene‐coated carbon nanotubes via microwave‐assisted in‐situ polymerization and tuning of the DC electrical conductivity and impedance characteristics

AbstractAn attempt has been made to tune the DC electrical conductivity and impedance characteristics of the nanocomposites by coating carbon nanotubes (CNTs). A microwave‐assisted in‐situ polymerization approach is utilized to coat the CNTs with polystyrene and no initiators are used. The nanocomposites are characterized by FE‐SEM, TEM, FT‐IR, Raman and TGA. Based on the morphological studies, a polystyrene layer is detected on the CNTs. According to the TGA results, the weight loss in the temperature range of polystyrene decomposition increases with increasing microwave irradiation time, suggesting a higher polystyrene content. Moreover, the DC electrical conductivity of the nanocomposites, as well as the real and imaginary impedance and dielectric permittivity are explored. It is shown that increasing the irradiation time decreases the DC electrical conductivity and dielectric permittivity but increases the real and imaginary impedance. Since the thickness of the polystyrene layer depends on the duration of microwave irradiation, our method can be used to tune the electrical conductivity and impedance characteristics. This can be applied to practical situations where a particular resistance is required.

Micro-Transfer Printing for Heterogeneous Integration of GaN and GaAs HEMTs

Here, we use the micro-transfer printing technique to demonstrate the device-level heterogeneous integration of two solid-state RF device technologies on the same interposer: GaN and GaAs high-electron-mobility transistors. The devices are released from their growth substrate using an epitaxial sacrificial layer while a thin polymer adhesion layer facilitates a strong bond between the target substrate and the compound semiconductor devices, allowing for post-transfer microfabrication processing. Transmission electron microscopy reveals no voids at the device/interposer interface and a polymer adhesion layer thickness of 5 ± 2 nm. No significant degradation in dc electrical characteristics is observed after device transfer for either device technology. Improvement in thermal performance of GaN devices was demonstrated when transferred to a diamond substrate, even with the thin polymer adhesion layer at the device/interposer interface, illustrating a pathway for enhanced thermal management for GaN and other high-output-power density semiconductor technologies. The ability to combine various solid-state technologies at the device level with high density provides an approach to meet next-generation demands for RF and mixed-signal circuits.

(Invited) Cryogenic Electronics for Quantum Computing ICs: What Can Bring FDSOI

We present an overview of the performances of FDSOI CMOS transistors down to deep cryogenic temperature, highlighting in particular the benefits brought by the back bias. FDSOI transistors are operational from room temperature down to temperature as low as 100mK. The main DC electrical characteristics, as well as variability properties and reliability are measured and analyzed. We also point out specific behaviors appearing at cryogenic temperature, and discuss their physical origin and modeling.

Unconventional conductivity increase in multilayer black phosphorus

Multilayers of so-called 2D van der Waals materials have gained considerable attention as active components of next-generation electronic and optoelectronic technologies, with semiconducting black phosphorus (BP) regarded as one of the most promising systems. The applicability and performance limits of BP in both stand-alone and heterostructure-based multilayer devices are determined by individual flake charge transport properties, which synergistically depend on the number of layers and the strength of interlayer coupling between those. In this work, we study the DC electrical transport characteristics of high-quality BP field-effect devices within a wide range of flake thicknesses at room temperature. The experimental data show a non-trivial increase in conductivity and hole density with a reduced number of layers while maintaining constant field-effect mobility due to the prevalence of electron–phonon scattering. Based on the solution of the 1D Schrödinger–Poisson equation, we find that the observed phenomena are a direct consequence of non-negligible interlayer coupling, which in turn causes a local redistribution of free charge carriers towards the central layers. Our data show that due to the electrostatic conditions at the flake surfaces, a naturally protected 2D hole gas can be encapsulated in flakes as high as 10 nm, which preserves the bulk-like bandgap and effective carrier masses due to the electrostatic environment.

Investigation of Anomalous Degradation Tendency of Low-Frequency Noise in Irradiated SOI-NMOSFETs

In this work, we present new evidence of the physical mechanism behind the generation of low-frequency noise with high interface-trap density by measuring the low-frequency noise magnitudes of partially depleted (PD) silicon-on-insulator (SOI) NMOSFETs as a function of irradiation dose. We measure the DC electrical characteristics of the devices at different irradiation doses and separate the threshold-voltage shifts caused by the oxide-trap charge and interface-trap charge. Moreover, the increased densities of the oxide-trap charge projected to the Si/SiO2 interface and interface-trap charge are calculated. The results of our experiment suggest that the magnitudes of low-frequency noise do not necessarily increase with the increase in border-trap density. A novel physical explanation for the low-frequency noise in SOI-NMOSFETs with high interface-trap density is proposed. We reveal that the presence of high-density interface traps after irradiation has a repressing effect on the generation of low-frequency noise. Furthermore, the exchange of some carriers between border traps and interface traps can cause a decrease in the magnitude of low-frequency noise when the interface-trap density is high.

Organic Vapor Sensing Mechanisms by Large-Area Graphene Back-Gated Field-Effect Transistors under UV Irradiation.

The gas sensing properties of graphene back-gated field-effect transistor (GFET) sensors toward acetonitrile, tetrahydrofuran, and chloroform vapors were investigated with the focus on unfolding possible gas detection mechanisms. The FET configuration of the sensor device enabled gate voltage tuning for enhanced measurements of changes in DC electrical characteristics. Electrical measurements were combined with a fluctuation-enhanced sensing methodology and intermittent UV irradiation. Distinctly different features in 1/f noise spectra for the organic gases measured under UV irradiation and in the dark were observed. The most intense response observed for tetrahydrofuran prompted the decomposition of the DC characteristic, revealing the photoconductive and photogating effect occurring in the graphene channel with the dominance of the latter. Our observations shed light on understanding surface processes at the interface between graphene and volatile organic compounds for graphene-based sensors in ambient conditions that yield enhanced sensitivity and selectivity.

Performance Analysis on Complementary FET (CFET) Relative to Standard CMOS With Nanosheet FET

For the first time, by using 3-D TCAD, the advantage of using complementary FET (CFET), which has vertically stacked nanosheet nFET and pFET with shared gate, is compared to standard CMOS with nanosheet FETs in perspective of CMOS inverter performance. The comparative study on CMOS operation was performed between CFET and standard CMOS in 3-nm technology node. The results indicate that, when both devices have identical DC electrical characteristics, using CFET can increase the frequency by ~2.3% in iso-power and decrease power by ~7.3% in iso-frequency compared to the standard CMOS with separate n/pFETs while effectively reducing the area by ~55%. It is also investigated that such results are due to the approximately 4.5% low effective capacitance (C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">eff</sub> ) of the CFET compared to the standard CMOS. This low C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">eff</sub> of CFET arises from the stacked structure, which causes the gate-fringe electric field overlap and short via pitch between nFET and pFET. Furthermore, the performance of CFET by different n/pFET separation distances, channel lengths, and widths are analyzed. This study can provide critical insight into the performance improvement by using CFET for sub 3-nm technology.

Octavinyl polyhedral oligomeric silsesquioxane on tailoring the DC electrical characteristics of polypropylene

This work reports the effect of octavinyl polyhedral oligomeric silsesquioxane (OvPOSS) on tuning the electrical performance of polypropylene (PP). OvPOSS with different content are introduced into PP using the solution method. The microstructural morphology, crystallinity behaviour, breakdown strength, DC conductivity, space charge formation, and trapping level distribution are measured. The results indicate that the OvPOSS nanofiller can be dispersed uniformly with a doping content of 2.0 phr or less. The DC conductivity is decreased, and the breakdown strength of OvPOSS/PP nanocomposites is significantly increased. The space charge accumulation of the OvPOSS/PP nanocomposites is significantly suppressed due to the introduction of deeper traps by the OvPOSS nanofiller. Finally, the experimental results demonstrate that the OvPOSS nanofiller can greatly increase the electrical performance of the base PP and the OvPOSS/PP nanocomposites have much potential for HVDC applications. They further demonstrate that the PP is environmental-friendly due to its thermo-plastic property, which can be recycled after the manufacture.

A Study of Crystallographic and DC Electrical Characteristics of PPy/Ag Nanocomposites

ABSTRACT: Polypyrrole and polypyrrole / silver nanocomposites were fabricated by in-situ polymerization employing Ammonium Persulphate as an oxidizing agent. Nanocomposites were synthesized by combining polypyrrole and silver nanoparticles in various weight percentages (0.1%, 0.5%, 3%, 5% and 7% wt.). Crystallographic data were collected using X-ray diffraction. PPy particles were found to have an orthorhombic symmetry. In contrast, PPy/Ag nanocomposites were reported to have monoclinic structure. The crystallite size was determined by XRD using Scherrer equation and considered to be within 49 nm range. DC conductivity of pelletized samples was evaluated in the temperature range of 323.15k to 453.15k. The conductivity displayed an increase when the temperature is increased from 323.15k to 453.15k. Activation energies were determined from plots of Arrhenius for all nanocomposites. The findings indicated that the activation energy decrease with increasing the weight percentage of Ag nanoparticles in the nanocomposites.

An easy-to-fabricate source measure unit for real-time DC and time-varying characterization of multi-terminal semiconductor devices

A versatile Arduino based source measure unit (ASMU) is fabricated for measuring both the DC and low-frequency AC electrical characteristics of multi-terminal semiconductor devices. The ASMU system is capable of bidirectional voltage sourcing and current measurement in all four quadrants. The system is programmed with the LabVIEW environment for real-time data acquisition. The voltage bias and current measurement range are observed to be ±4.65 V and ±14.6 mA with an optimum resolution of 5 mV and 7.8125 μA, respectively. Both the two- and three-terminal passive and active devices can be characterized without changing any circuit configuration. The electronic and optoelectronic current-voltage, current-time, and transistor’s input/output characteristics can be performed only by customizing the programming codes. The performance of the ASMU system is found to be highly comparable with commercial measurement systems. The experimental results suggest its potential application in characterizing semiconductor devices with maintaining adequate precision, cost-effectiveness, and low-power consumption.

Performance Enhancement of Novel Dopingless TFET Using Raised Source and Recessed Drain

A novel raised source and recessed drain dopingless tunneling FET (RSRD-DL-TFET) is proposed in this paper. By using TCAD simulation, the DC electrical characteristics, energy-band diagrams, carrier concentrations and band-to-band tunneling generation rate of RSRD-DL-TFET are analyzed, as compared with planar dopingless tunneling FET (PDL-TFET). Besides, analog/RF and transient performances for both devices are also investigated, including transconductance, parasitic gate capacitance, cut-off frequency, gain bandwidth product and fall propagation delay. Benefiting from the design of raised source and recessed drain, the proposed device not only creates the line tunneling in the source region, but also reduces the ambipolar tunneling distance at drain/channel interface. As a result, the proposed RSRD-DL-TFET could provide higher on-current, steeper subthreshold swing, lower ambipolar current, higher cut-off frequency and better transient performance than PDL-TFET.