Variation Of Bias Voltage Research Articles

Insight into the Impact of Electron Drift Trajectory on Charge Collection in Silicon Drift Detector

The internal electric field distribution is one key design consideration, which affects the charge collection efficiency in silicon drift detectors (SDDs). The internal electrostatic potential distributions along SDD front and back surfaces, which are determined by the applied voltages at cathode electrodes, define the final internal field distribution. Front-back bias coupling leads to the complexity of electrode structure design and voltage tuning. Device simulation is performed to investigate the performance of SDDs with varied bias voltages. When the cathode bias is −40 V with the first ring bias of −15 V and the outermost ring bias of −80 V, the detector is biased with a uniform electric field distribution, favorable electron drift trajectories. The simulation results provide new insight into the influence of internal electric field and electron drift trajectories on the charge collection efficiency. According to the analysis of simulation results, a 2000 × 2000 μm area concentric silicon drift detector was designed and fabricated. The electrical characteristics of the designed detectors were studied to show the validity of the proposed device design methodology. The internal electric field distribution and electron drift trajectories can be tuned to improve the charge collection efficiency.

Effect of deposition parameters on structural and mechanical properties of Novel h-BN doped TiCrNbN coatings

In this paper, the novel h-BN doped TiCrNbN thin films was deposited on the DIN 1.2714 steel using closed field unbalanced magnetron sputtering (CFUBMS) technique with variable working pressure, bias voltage, and LaB6 target voltage. The main goal is to determine the contribution of degrees of these parameters on structural and mechanical properties using Analysis of Variance (ANOVA). The deposition parameters were leveled based on L9 (33) orthogonal Taguchi design method. Microstructural and thickness of coatings were investigated using SEM. The coatings had granular and flawless surface properties. The thickness of the coatings was determined in the range of 874 nm and 1.69 μm. The deposition parameter that has the highest contribution to coating thickness is working pressure. Hardness and adhesion strength of coatings were determined employing nanohardness and scratch tester, respectively. The highest hardness among the coatings was 24.67 GPa, obtained with the 3x10-3 Torr working pressure, 100 V bias voltage and 600 V LaB6 target voltage parameters. The deposition parameter that has the highest contribution to hardness is working pressure. The coating conditions with the highest hardness exhibited the highest adhesion strength. The superiority of the contribution of working pressure on the adhesion strength was prominent compared to other parameters.

Sputter deposited silver niobate thin films: Pathway towards phase purity

The quest for environmentally sustainable alternatives to lead-based dielectric materials in dielectric capacitors has led research to the exploration of options such as silver niobate (AgNbO3), which has been found to display excellent energy storage properties. Homogeneity and phase-purity of the used thin films are vital for optimal performance of these devices. In this study, a systematic variation of oxygen partial pressure and bias voltage during reactive d.c. magnetron co-sputtering from metallic targets is employed to synthesise AgNbO3 thin films. Structural and chemical composition of the films are investigated using X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy, elastic recoil detection analysis, and Rutherford backscattering spectrometry. The findings emphasise the necessity of precise parameter control during deposition to avoid the presence of undesirable secondary phases like Ag and Ag2Nb4O11 and to ensure the formation of homogeneous and phase-pure AgNbO3 thin films. The gained insights demonstrate the potential of reactive d.c. magnetron sputtering for the deposition of lead-free AgNbO3 thin films, offering pathways for enhanced environmental compatibility of future dielectric capacitors.

Residual stresses prediction in transition metal nitrides sputtered coatings using artificial neural network and experimental evaluation of surface morphology

In the production of transition metal nitride hard coatings under specific deposition conditions, the resulting residual stresses play a critical role in determining the mechanical properties, adhesion, and overall performance of the coatings. In this work, an artificial neural network (ANN) that utilizes feed-forward architecture is used to predict the average residual stress in titanium nitride (TiN) coatings with different coating thickness. These coatings are manufactured under varying bias voltages and temperature on substrate. The impact of variations in coating thickness, bias voltage, and temperature on development of internal residual stresses and changes in microstructure within sputtered coatings have been gathered from existing literature. The data collected is within the context of fibrous (zone I) and mix columnar and fibrous structure (combined zone) as defined by an existing structure zone model. The model is trained with experimental data from literature. The model is trained with experimental data from literature. The validation of the ANN model is carried out by comparing the predictions with experimental results. X-ray diffraction is used to analyze the residual stresses, preferred orientation, and the structure (zone I and combined zone) of produced coatings under different sputtering parameters. The regression and performance curves are used to assess the efficacy of ANN model. The coefficient of determination of trained model and mean square error are 0.9918 and 0.35, respectively. The predicted results show good agreement with experimental and subsequently AFM grain morphology analysis captures the growth mechanisms involved in the residual stresses evolution.

Voltage-insensitive stochastic magnetic tunnel junctions with double free layers

Stochastic magnetic tunnel junction (s-MTJ) is a promising component of probabilistic bit (p-bit), which plays a pivotal role in probabilistic computers. For a standard cell structure of the p-bit, s-MTJ is desired to be insensitive to voltage across the junction over several hundred millivolts. In conventional s-MTJs with a reference layer having a fixed magnetization direction, however, the stochastic output significantly varies with the voltage due to spin-transfer torque (STT) acting on the stochastic free layer. In this work, we study a s-MTJ with a “double-free-layer” design theoretically proposed earlier, in which the fixed reference layer of the conventional structure is replaced by another stochastic free layer, effectively mitigating the influence of STT on the stochastic output. We show that the key device property characterized by the ratio of relaxation times between the high- and low-resistance states is one to two orders of magnitude less sensitive to bias voltage variations compared to conventional s-MTJs when the top and bottom free layers are designed to possess the same effective thickness. This work opens a pathway for reliable, nanosecond-operation, high-output, and scalable spintronics-based p-bits.

Performance parameters estimation of high speed Silicon/Germanium/InGaAsP avalanche photodiodes wide bandwidth capability in ultra high speed optical communication system

Abstract This paper has clarified the performance parameters estimation of high speed silicon/germanium/InGaAsP avalanche photodiodes wide bandwidth capability in ultrahigh speed optical communication system. The basic structure configuration of avalanche photodiode is clarified. The basic depletion region configuration schematic view is demonstrated. As well as the maximum electric field is indicated for impact ionization through avalanche photodiode in the presence of load. Various avalanche photo-detectors multiplication factor is clarified versus reverse bias voltage at room temperature. Different avalanche photo-detectors dark current is measured against avalanche photo-detectors volume at room temperature. Various avalanche photo-detectors effective doping concentration is demonstrated against ambient temperature variations. Si/Ge/InGaAsP avalanche photo-detectors excess noise factor is demonstrated versus the ionization ratio at room temperature (T = 300 K) and different ambient temperature (T = 350 K and T = 400 K). Various avalanche photo-detectors excess noise factor is measured clearly versus the multiplication factor at room temperature. Si/Ge/InGaAsP avalanche photo-detectors excess noise factor is demonstrated versus reverse bias voltage at room temperature. Si/Ge/InGaAsP avalanche photo-detectors noise equivalent power is clarified versus multiplication factor at room temperature. Various avalanche photo-detectors noise equivalent power is studied versus temperature variations. Si/Ge/InGaAsP avalanche photo-detectors sensitivity is measured in relation to the temperature variations. Different avalanche photo-detectors sensitivity is demonstrated in relation to reverse bias voltage variations at room temperature.

Control of the preferential orientation and properties of HiPIMS and DCMS deposited chromium coating based on bias voltage

This study investigates the effects of varying bias voltages on the crystallographic orientation and properties of DCMS + HiPIMS-deposited chromium coatings. Under bias voltages varying from 100 to 500 V, dense Cr coatings were obtained, and the deposition rate decreased by 13 %. The bias voltage significantly impacts the hardness, crystallographic orientation, electrical conductivity, and bonding strength of the coating. As the bias voltage increases, the hardness of the Cr coating gradually increases. The crystallographic orientation of the coating is governed collectively by surface energy, strain energy, and sputtering effects. The preferential crystallographic orientation of the Cr coating transitions from (222) to (110), subsequently changing to a mixed preferential crystallographic orientation of (110), (211), and (222). Under the combined influence of thermal effects and ion bombardment, a (110) preferential crystallographic orientation was obtained at a bias voltage of 300 V, featuring moderate hardness and optimal wear resistance. This study establishes that the electrical characteristics of the coatings have a significant correlation with bias voltage levels.

Enhancing sp3 formation in DLC on low thermal conductivity substrate: Interval deposition minimizing ion energy sensitivity

Depositing sp3-rich diamond-like carbon (DLC) on low thermal conductivity substrates is difficult due to the high sensitivity of sp3 formation to ion energy. This sensitivity is attributed to the heating effect of ion bombardment during plasma-enhanced chemical vapor deposition (PECVD) processing. This study introduced an interval deposition method aimed at minimizing the ion energy sensitivity, thereby achieving sp3-rich DLC deposition and broadening the process window. The variation in sp3 content of deposited DLC showed that the interval deposition can enhance sp3 formation, which is particularly significant when the single deposition duration is ≤1 s and the ratio of interval duration to deposition duration is ≥3. Deposition experiments with varying bias voltages confirmed that the ion energy sensitivity of sp3 formation in DLC can be effectively reduced by the proposed method. The analysis of transient film temperature during the deposition process revealed that this method took effect by limiting the temperature elevation of the film. Performance comparison showed that the adhesion of films to the substrate was improved by 138 % using the interval deposition method, compared to the traditional continuous deposition. This user-friendly and high-tolerance deposition method can significantly advance the application fields of DLC coatings.

Integrated Photoelectrochemical-SERS Platform Based on Plasmonic Metal-Semiconductor Heterostructures for Multidimensional Charge Transfer Analysis and Enhanced Patulin Detection.

Comprehending the charge transfer mechanism at the semiconductor interfaces is crucial for enhancing the electronic and optical performance of sensing devices. Yet, relying solely on single signal acquisition methods at the interface hinders a comprehensive understanding of the charge transfer under optical excitation. Herein, we present an integrated photoelectrochemical surface-enhanced Raman spectroscopy (PEC-SERS) platform based on quantum dots/metal-organic framework (CdTe/Yb-TCPP) nanocomposites for investigating the charge transfer mechanism under photoexcitation in multiple dimensions. This integrated platform allows simultaneous PEC and SERS measurements with a 532 nm laser. The obtained photocurrent and Raman spectra of the CdTe/Yb-TCPP nanocomposites are simultaneously influenced by variable bias voltages, and the correlation between them enables us to predict the charge transfer pathway. Moreover, we integrate gold nanorods (Au NRs) into the PEC-SERS system by using magnetic separation and DNA biometrics to construct a biosensor for patulin detection. This biosensor demonstrates the voltage-driven ON/OFF switching of PEC and SERS signals, a phenomenon attributed to the plasmon resonance effect of Au NRs at different voltages, thereby influencing charge transfer. The detection of patulin in apples verified the applicability of the biosensor. The study offers an efficient approach to understanding semiconductor-metal interfaces and presents a new avenue for designing high-performance biosensors.

Electrical and dielectric characterization of Ge quantum dots embedded in MIS structure (AuPd/SiO2:Ge QDs/n-Si) grown by MBE

Monocrystalline Germanium quantum dots (Ge QDs), grown by molecular beam epitaxy (MBE), are intricately embedded within a SiO2 oxide layer of a metal-insulator-semiconductor (MIS) structure, catering to optoelectronic applications. These monocrystalline Ge QDs exhibit high density (D ∼ 5 x 1012 cm−2), possess a spherical morphology, and an average size of 6 nm with narrow size distribution. A comprehensive investigation into the influence of these quantum dots on the electrical transport and dielectric properties of the metal-insulator-semiconductor (MIS) structure was conducted through current-voltage (I–V) spectroscopy and impedance spectroscopy. Notably, I–V measurements demonstrate that Ge QDs enhance conduction phenomena, thereby improving electrical transport within the MIS structure. Furthermore, the capacitance-voltage (C–V) and conductance-voltage (G-V) measurements, spanning the inversion and accumulation regions, demonstrate a memory effect induced by Ge QDs within the MOS structure. Extensive analysis of dielectric parameters, including permittivity (ε′), dielectric loss (ε”), dissipation factor (tanδ), as well as electrical modulus (M’ and M”), across a broad frequency range and under varying bias voltages, reveals no anomalous electrical or dielectric behavior attributable to the presence of Ge QDs in MIS structure. Consequently, these findings affirm the viability of the novel MIS structures with Ge QDs for the development of optoelectronic devices such as photodetectors or solar cells.

Optimized Tribological Performance of Nitrogen-Doped Diamond-like Carbon Films on NBR: Influence of Bias Voltage of DC Magnetron Sputtering.

In this research, nitrogen-doped diamond-like carbon (N-DLC) coatings were deposited on Nitrile Butadiene Rubber (NBR) substrates using direct current magnetron sputtering (DC-MS) under varying bias voltages. This study aimed to explore environmentally friendly, low-wear, and non-lubricating seal coatings to enhance the durability of rubber sealing products, which predominantly operate under dynamic sliding conditions. By reducing the coefficient of friction (CoF), the friction and wear on rubber products can be significantly minimized, extending their lifespan. This investigation thoroughly examined the microstructure, mechanical properties, and tribological behavior of the N-DLC films. Among the coatings, the one produced at a bias voltage of -50 V demonstrated superior hardness, elastic modulus, and the lowest CoF in comparison to those prepared with 0, -100, and -200 bias voltages. This optimal combination of properties resulted in an exceptionally low wear rate of 10-9 for the film deposited at -50 V, indicating its outstanding wear resistance.

Effect of bias voltages and interlayer design on microstructure, mechanical properties, and adhesion performance of AlCrSiN coatings deposited using HiPIMS

This study fabricated AlCrSiN coatings from six alloy targets (Four Al7Cr3 targets and two Cr9Si1 targets) using high-power impulse magnetron sputtering (HiPIMS) with a focus on the effects of substrate bias voltage (−30 to −90 V) on deposition rate, microstructure, crystal orientation, residual stress, and mechanical properties. Electron Probe Microanalysis (EPMA) and X-ray Diffraction (XRD) results revealed that variations in bias voltage had little impact on the element composition or crystal structure (FCC) of AlCrSiN coatings; however, under high bias voltage (exceeding −60 V), the preferred orientation shifted from the (111) plane to the (220). Increasing the bias voltage from −30 to −90 V was shown to reduce the deposition rate (from 42.2 to 37.6 nm/min) and the thickness of the AlCrSiN coating (from 2.9 to 2.6 μm). It was also shown to increase the hardness (from 2147 to 3658 HV) and residual stress (from −0.01 to −0.59 GPa) by reducing the grain size and allowing the formation of a denser structure. Various interlayer designs (AlCr/AlCrxNy/AlCrN, CrSi/AlCrxNy/AlCrN, AlCr/CrSixNy/CrSiN, CrSi/CrSixNy/CrSiN) were assessed in terms of adhesion strength between the AlCrSiN and substrate. Under the same AlCrSiN deposition condition, with the bias voltage set to −60 V, the highest adhesion strength (from 32.28 to 45.81 N) was achieved using a CrSi/CrSixNy/CrSiN interlayer structure.

Effect of Sputtering Bias Voltage on the Microstructure and Lead-Bismuth Eutectic Corrosion Resistance of the FeCrAlY Coating

FeCrAlY coatings deposited on the outer surface of the cladding tube by the magnetron sputtering with varying bias voltages (0 V to −500 V) were corroded at 550°C to 600°C in oxygen-saturated and oxygen-poor lead-bismuth eutectic for 500 h to 1,000 h. The increased bias voltage led to the Al content decreased and the Y content increased. The coating changed from columnar crystals to equiaxed crystals with increased bias voltage. The decreased bias voltage makes an improved corrosion resistance. The fundamental process governing the evolution of microstructure and corrosion resistance in the FeCrAlY coatings was discussed.

Separation of mass and gap errors of hemispherical resonator gyroscopes by varying bias voltage

For hemispherical resonator gyroscopes (HRGs), mass imperfections and capacitive gap nonuniformity jointly influence the frequency mismatch and degrade the gyroscope performance. However, the coupling mechanism and separation of these two errors are rarely discussed. This paper proposes, for the first time, a novel method of separating mass imperfections and gap nonuniformity of HRGs, based on a dynamics model considering both the two errors. By measuring the frequency mismatches and principal axes of stiffness at different bias voltages, the mass imperfections and gap nonuniformity can be separately obtained. The method is investigated in detail by simulation, and validated by experiment on three different HRGs. The experimental results agree well with the theoretical analysis, demonstrating the effectiveness of the model and the separation method. Our method may contribute to high-precision HRG manufacture, and can be conveniently applied to other Coriolis vibrating gyroscopes (CVGs) with electrostatic actuation.

Preliminary experimental research on RF coupling efficiency of CRAFT NNBI prototype ion source

A radio frequency inductively coupled plasma source was chose as the prototype ion source for CRFAT NNBI system. The RF coupling efficiency of this negative ion(H−) source is researched by experiment. The effect of the RF ion source’s multi-cusp confinement magnet on the RF coupling efficiency is focused on. It is found that the RF ion source, equipped with a linear type cusp magnet array on the expansion chamber walls, exhibits a higher efficiency of 2% to 6.6% compared to the checkerboard type. Furthermore, the RF coupling efficiency improves by approximately 9% when a confinement magnet is used, as opposed to not having one. The variations in bias voltage have no impact on the RF coupling efficiency. Nonetheless, variations in the magnetic field within the driver region caused by changes in the PG current induce an impact on the plasma in that region. When the PG current was raised from 800 A to 2500 A, it led to a minor reduction in RF coupling efficiency of approximately 2%.

Investigating mechanical properties of B4C films produced by magnetron sputtering PVD

Boron carbide thin films have recently garnered significant interest across various fields owing to their exceptional physical and chemical properties, such as high wear and corrosion resistance, as well as high hardness, being the third hardest material after diamond and cubic boron nitride. Different coating methods, including physical vapor deposition (PVD) and chemical vapor deposition (CVD), are used to produce these films. In this study, boron carbide thin films were deposited on single-crystal silicon substrates and high-speed steel (HSS) using magnetron sputtering at varying bias voltages (0, −100, and −200 V) in an argon atmosphere utilizing a B4C target. The process temperature, target power, and revolution speed were held constant at 150 °C, 1.3 kW, and 2 rpm, respectively. The mechanical, morphological, and microstructure properties of the deposited films were examined using FE-SEM, XRD, FTIR, Raman, XPS, Scratch test and Ferroxyl test. Nanoindentation test was conducted to evaluate the hardness values of the films. The experimental findings suggest that substrate bias significantly affects the mechanical, structural, and morphological properties of B4C coatings.

Photothermally Activated Artificial Neuromorphic Synapses.

Biological nervous systems rely on the coordination of billions of neurons with complex, dynamic connectivity to enable the ability to process information and form memories. In turn, artificial intelligence and neuromorphic computing platforms have sought to mimic biological cognition through software-based neural networks and hardware demonstrations utilizing memristive circuitry with fixed dynamics. To incorporate the advantages of tunable dynamic software implementations of neural networks into hardware, we develop a proof-of-concept artificial synapse with adaptable resistivity. This synapse leverages the photothermally induced local phase transition of VO2 thin films by temporally modulated laser pulses. Such a process quickly modifies the conductivity of the film site-selectively by a factor of 500 to "activate" these neurons and store "memory" by applying varying bias voltages to induce self-sustained Joule heating between electrodes after activation with a laser. These synapses are demonstrated to undergo a complete heating and cooling cycle in less than 120 ns.

Регульований смуговий фільтр на основі кільцевих резонаторів для мікрохвильових застосунків

The paper presents the principle of a microwave adaptive band-pass filter based on the cascade of ring resonators. The filter is performed as a planar microstrip technology with thickness of around 1 mm to ensure compactness of the device. The ring resonators, being a part of metamaterials, can be considered as an equivalence of an oscillator and is conventionally used in the microwaves. While a quite number of the filters with predefined parameters are well-known, the adaptive filters the throughput and output characteristics of which can be adjusted depending on the input ones is the topical problematic nowadays and, at least, for the closest future. We have investigated in the paper the possibilities of adjustment the considered filter’s transmission characteristics through the ring design, distance between them, and discussed other features, which have impact. For example, it allows expanding of the filter bandwidth from 250 to 60 MHz for simultaneous change of a distance between the adjacent rings. We have suggested the approach how to do the filter time-dependent. A varactor diode inserted into the gap of the middle ring is controlled with an independent external source and can adjust the filter bandwidth from 80 up to 140 MHz for the varactor capacitance variation from 16 to 6 pF (bias voltage variation from 1 to 7 V) that covers the existing communication networks, such as mobile generations, Bluetooth, Wi-Fi, etc. and can be applied for modern smart technologies of the Internet-of-Things for a remote control. It becomes possible because different sensing elements, such as photodiodes, Hall effect sensors, photoresistors, etc., can be exploited as the aforementioned external source.

Single-molecule photoelectron tunnelling spectroscopy.

Experimental mapping of transmission is essential for understanding and controlling charge transport through molecular devices and materials. Here we developed a single-molecule photoelectron tunnelling spectroscopy approach for mapping transmission beyond the HOMO-LUMO gap of the single diketopyrrolopyrrole molecule junction using an ultrafast-laser combined scanning tunnelling microscope-based break junction set-up at room temperature. Two resonant transport channels of ultrafast photocurrent are found by our photoelectron tunnelling spectroscopy, ranging from 1.31 eV to 1.77 eV, consistent with the LUMO + 1 and LUMO + 2 in the transmission spectrum obtained by density functional theory calculations. Moreover, we observed the modulation of resonant peaks by varying bias voltages, which demonstrates the ability to quantitatively characterize the effect of the electric field on frontier molecular orbitals. Our single-molecule photoelectron tunnelling spectroscopy offers an avenue that allows us to explore the nature of energy-dependent charge transport through single-molecule junctions.

Ultra-Low-Power Compact Neuron Circuit with Tunable Spiking Frequency and High Robustness in 22 nm FDSOI

Recent years have seen an increasing popularity in the development of brain-inspired neuromorphic hardware for neural computing systems. However, implementing very large scale simulations of neural networks in hardware is still an open challenge in terms of power efficiency, compactness, and biophysical resemblance. In an effort to design biologically plausible spiking neuron circuits while restricting power consumption, we propose a new subthreshold Leaky Integrate-and-Fire (LIF) neuron circuit designed using 22 nm FDSOI technology. In this circuit, problems of large leakage currents and device mismatch are effectively reduced by deploying the back-gate terminal of FDSOI technology for a tunable design. The proposed neuron is able to operate in two spiking frequency modes with tunable bias parameter setting of key transistors, and it results in complex firing behaviors, such as adaptation, chattering, and bursting, through varying bias voltages. We present circuit post-layout simulation results and demonstrate the biologically plausible neural dynamics. Compared with published state-of-the-art neuron circuits, the circuit dissipates ultra-low energy per spike, on the order of femtojoules per spike, at firing rates ranging from 30 Hz to 1 kHz. Furthermore, the circuit is proven to maintain a good robustness over process variation and Monte Carlo analysis, with relative error 3.02% at a firing rate of approximately 67.1 Hz.