Stable photocurrent-voltage characteristics of perovskite single crystal detectors obtained by pulsed bias

Photocurrent-voltage characterization is a crucial method for assessing key parameters in x-ray or y-ray semiconductor detectors,especially the carrier mobility lifetime product.However,the high biases during photocurrent measurements tend to cause severe ion migration,which can lead to the instability and inaccuracy of the test results.Given the mixed electronic-ionic charac teristics,it is imperative to devise novel methods capable of precisely measuring photocurrentvoltage characteristics under high bias conditions,free from interference caused by ion migration.In this paper,pulsed bias is employed to explore the photocurrent-voltage characteristics of MAPbBr_(3) single crystals.The method yields stable photocurrent-voltage characteristics at a pulsed bias of up to 30 V,proving to be effective in mitigating ion migration.Through fitting the modified Hecht equation,we determined the mobility lifetime products of 1.0×10^(2) cm^(2)·V^(-1)for hole and 2.78×10~(-3)cm^(2)·V^(-1)for electron.This approach offers a promising solution for accurately measuring the transport properties of carriers in perovskite.

Experimental Verification of the Physical Model for Droplet-Particles Cleaning in Pulsed Bias Arc Ion Plating

It has been reported that application of pulsed biases in arc ion plating could effectively eliminate droplet particles. The present paper aims at experimental verification of a physical model proposed previously by us which is based on particle charging and repulsion in the pulsed plasma sheath. An orthogonal experiment was designed for this purpose, using the electrical parameters of the pulsed bias for the deposition of TiN films on stainless steel substrates. The effect of these parameters on the amount and the size distribution of the particles were analyzed, and the results provided sufficient evidence for the physical model.

Effect of pulsed bias on the properties of ZrN/TiZrN films deposited by a cathodic vacuum arc

ZrN/TiZrN multilayers are deposited by using the cathodic vacuum arc method with different substrate bias（from 0 to 800 V）,using Ti and Zr plasma flows in residual N 2 atmosphere,combined with ion bombardment of sample surfaces.The effect of pulsed bias on the structure and properties of films is investigated.Microstructure of the coating is analyzed by X-ray diffraction（XRD）,and scanning electron microscopy（SEM）.In addition,nanohardness,Young＇s modulus,and scratch tests are performed.The experimental results show that the films exhibit a nanoscale multilayer structure consisting of TiZrN and ZrN phases.Solid solutions are formed for component TiZrN films.The dominant preferred orientation of TiZrN films is（111） and（220）.At a pulsed bias of 200 V,the nanohardness and the adhesion strength of the ZrN/TiZrN multilayer reach a maximum of 38 GPa,and 78 N,respectively.The ZrN/TiZrN multilayer demonstrates an enhanced nanohardness compared with binary TiN and ZrN films deposited under equivalent conditions.

FUNDAMENTAL PROBLEMS IN PULSED-BIAS ARC DEPOSITION

Arc deposition, a widely used surface coating technique, has disadvantages such as large droplet size and high deposition temperature. Recent trend in its renovation is the introduction of pulsed bias at the. substrate. The present paper attempts to describe the deposition process of TiN films using this technique with emphasis laid on the understanding of the basic problems such as discharge plasma properties, temperature calculation, and droplet size reduction. We show that this technique improves the film micro structure and quality, lowers deposition temperature, and allows coatings on insulating substrates. After analyzing load current oscillation behaviors, we have determined that the plasma load is of capacitance nature due to plasma sheath and that it is equivalent to a circuit element consisting of parallel capacitance and resistance. At last, we point out the remaining problems and future development of the pulsed-bias arc deposition technique.

Derivation of Floquet Eigenvectors Displacement for Optimal Design of LC Tank Pulsed Bias Oscillators

The paper presents an approximated and compact derivation of the mutual displacement of Floquet eigenvectors in a class of LC tank oscillators with time varying bias. In particular it refers to parallel tank oscillators of which the energy restoring can be modeled through a train of current pulses. Since Floquet eigenvectors are acknowledged to give a correct decomposition of noise perturbations along the stable orbit in oscillator's space state, an analytical and compact model of their displacement can provide useful criteria for designers. The goal is to show, in a simplified case, the achievement of oscillators design oriented by eigenvectors. To this aim, minimization conditions of the effect of stationary and time varying noise as well as the contribution of jitter noise introduced by driving electronics are deduced from analytical expression of eigenvectors displacement.

Role of Duty Ratio in Diamond Growth by Pulsed DC-Bias Enhanced Hot Filament Chemical Vapour Deposition

In this study, the role of the pulse duty ratio was investigated during the deposition of diamond films in a hot filament chemical vapour deposition reactor with a pulsed-tic biased substrate positively relative to the hot filaments. The voltage-current characteristics showed that the discharge current rose with the increase of biasing voltage, which was modified by the duty ratio. Before deposition, two approaches were adopted for the pre-treatment of the silicon substrates, respectively, and the substrates were scratched by diamond paste or seeded by diamond powders using the so-called ＇soft dry polished＇ technique. Diamond films were deposited under a fixed discharge power by changing the duty ratios. In the first group with scratched substrates, it was found that under a high duty ratio the diamond grew slowly with quite poor nucleation, while in the second case a high duty ratio induced a high deposition rate and good diamond qual- ity. Reactive hydrocarbon species with high energy are essential for the initial nucleation process, which is more effectively achieved at a high biasing voltage in the condition of a low duty ratio. In the film growth process, the large discharge current at a high duty ratio represents an increased concentration of electrons and reactive species as well, promoting the growth of diamond films.

Deposition of Ti-AI-N Films by Using a Cathodic Vacuum Arc with Pulsed Bias

Ti-Al-N hard films have been prepared by cathodic arc deposition by using an unipolar pulsed bias.In the present study,Ti-Al-N films were deposited on stainless steel and silicon wafers.The deposition rate,micrograph,preferred orientation and composition were systematically investigated by usingx-ray diffraction（XRD）,energy dispersive X-ray spectroscopy（EDX）, and a scanning electron microscope（SEM）.It is shown that substate bias duty cycle and frequency have a great effect on film structure.A simple explanation for the results is also presented.

Phase and Quadrature Pulsed Bias LC-CMOS VCO

Pulsed bias is an attempt to improve the performance of oscillators in integrated circuits as a result of architectural innovation. Given the relatively low value of resonator quality factor achievable on-chip, for a specified bias voltage level, pulsed bias may result in a lower power consumption and in an improvement of the spectral purity of the oscillation. The main drawback of this approach is the need to introduce a certain time delay in order to properly position pulses with respect to oscillation waveform. Delay accumulation requires further energy dissipation and introduce additional jitter. In this paper we present a new architecture capable to avoid unnecessary delay, based on the idea to apply the pulsed bias approach to a quadrature oscillator. A ?rst circuit-level implementation of this concept is presented with simulation results.

Floquet Eigenvectors Theory of Pulsed Bias Phase and Quadrature Harmonic Oscillators

The paper presents an analytical derivation of Floquet eigenvalues and eigenvectors for a class of harmonic phase and quadrature oscillators. The derivation refers in particular to systems modeled by two parallel RLC resonators with pulsed energy restoring. Pulsed energy restoring is obtained through parallel current generators with an impulsive characteristic triggered by the resonators voltages. In performing calculation the initial hypothesis of the existence of stable oscillation is only made, then it is verified when both oscillation amplitude and eigenvalues/eigenvectors are deduced from symmetry conditions on oscillator space state. A detailed determination of the first eigenvector is obtained. Remaining eigenvectors are hence calculated with realistic approximations. Since Floquet eigenvectors are acknowledged to give the correct decomposition of noise perturbations superimposed to the oscillator space state along its limit cycle, an analytical and compact model of their behavior highlights the unique phase noise properties of this class of oscillators.

THE EFFECTS OF PULSE BIAS VOLTAGE AND N_2 PARTIAL PRESSURE ON TiAlN FILMS OF ARC ION PLATING (AIP)

Owing to the characteristics of arc ion plating(AIP) technique, the structure and composition of TiAlN films can be tailored by controlling of various parameters such as compositions of target materials, N2 partial pressure, substrate bias and so on. In this study, several titanium aluminum nitride films were deposited on 1Cr11Ni2W2MoV steel for compressor blade of areo-engine under different d.c pulse bias voltage and nitrogen partial pressure. The effects of substrate pulse bias and nitrogen partial pressure on the deposition rate, droplet formation, microstruture and elemental component of the films were investigated.

Effect of supply voltage and body-biasing on single-event transient pulse quenching in bulk fin field-effect-transistor process

Charge sharing is becoming an important topic as the feature size scales down in fin field-effect-transistor （FinFET） technology. However, the studies of charge sharing induced single-event transient （SET） pulse quenching with bulk FinFET are reported seldomly. Using three-dimensional technology computer aided design （3DTCAD） mixed-mode simulations, the effects of supply voltage and body-biasing on SET pulse quenching are investigated for the first time in bulk FinFET process. Research results indicate that due to an enhanced charge sharing effect, the propagating SET pulse width decreases with reducing supply voltage. Moreover, compared with reverse body-biasing （RBB）, the circuit with forward body-biasing （FBB） is vulnerable to charge sharing and can effectively mitigate the propagating SET pulse width up to 53% at least. This can provide guidance for radiation-hardened bulk FinFET technology especially in low power and high performance applications.

Effect of Sample Configuration on Droplet-Particles of TiN Films Deposited by Pulse Biased Arc Ion Plating

Orthogonal experiments are used to design the pulsed bias related parameters, including bias magnitude, duty cycle and pulse frequency, during arc ion deposition of TiN films on stainless steel substrates in the case of samples placing normal to the plasma flux. The effect of these parameters on the amount and the size distribution of droplet-particles are investigated, and the results have provided sufficient evidence for the physical model, in which particles reduction is due to the case that the particles are negatively charged and repulsed from negative pulse electric field. The effect of sample configuration on amount and size distribution of the particles are analyzed. The results of the amount and size distribution of the particles are compared to those in the case of samples placing parallel to the plasma flux.

直流偏置型游标磁阻电机系统低开关频率交替箝位PWM策略

提出一种具有零序电流调节能力的直流偏置型游标磁阻电机(DC-biased vernier reluctance machine,DC-biased-VRM)系统低开关频率交替箝位脉宽调制(pulse width modulation,PWM)策略。DC-biased-VRM利用电枢绕组中附加的直流偏置电流来构建转子磁链,为调节直流偏置电流,采用开绕组逆变器提供零序电流通路。相比于传统三相逆变器,开关动作的次数增加了1倍,在调整直流偏置电流、降低开关损耗方面存在一定优化空间。针对以上改进需求,引入交替箝位控制方式,并提出重新配置的零电压矢量实现零序电压的实时调节,保证零序电流的调节能力。最后,通过样机实验验证提出策略的有效性。提出策略可以减少开关动作次数,保证逆变器的低开关损耗,为提高DC-biased-VRM驱动系统效率提供有效的解决方案。

Exchange Bias Effect in Phase Separated La0.33Pr0.34Ca0.33MnO3 Thin Films

Exchange bias effect is observed in the phase separated La0.33Pr0.34Ca0.33MnO3 thin films. High exchange bias field of about 1 kOe is achieved at 4 K. The exchange bias effect in La0.33Pr0.34Ca0.33MnO3 thin films might originate from the intrinsic phase separation of the La0.33Pr0.34Ca0.33MnO3 or surface effect. The dependence of exchange bias effect on temperature, cooling field, and thickness is also investigated. This work would open an avenue to the application in the magnetic memory devices based on the phase separated manganites.

强流脉冲离子束产生的实验研究

分析了箍缩反射离子的工作原理,实验研究了二极管结构参数对其电参数的影响。在200 kV加速器装置上获得了最大峰值2.1 kA、脉宽约20 ns、束能5.5 J的离子流,最大离子产生效率达到6.2％。

α-Si:H太阳电池的反偏压和强脉冲光照研究

研究了各种反向偏压和强脉冲光照对 a-Si:H 太阳电池性能的影响。发现在室温下进行3～5V、30分的反偏压处理能改善电池的性能。证明了经室内光照和室外长期暴露,反偏压处理和强脉冲光照/热退火循环能减少电池的光致衰降,提高电池的稳定性。

一种电网尖脉冲干扰滤波器设计方法

提出了用分布电容可以忽略的磁芯电感器与寄生电感很小的穿心电容器相结合的尖脉冲干扰滤波器设计方案,并详尽地给出了尖脉冲干扰滤波器的设计方法。阐述了磁芯电感器滤波原理,给出了尖脉冲干扰滤波器的结构和原理,给出了尖脉冲干扰滤波器磁材料与磁芯结构的选择方法、线圈匝数和磁芯截面积的计算方法,给出了设计实例、实验方法以及实验结果。实验结果表明所提出的尖脉冲干扰滤波器设计方案是可行的。利用此方法可以设计出经济实用的尖脉冲干扰滤波器。

Constant fraction discriminator in pulsed time-of-flight laser rangefinding

Constant fraction discriminator （CFD） is one of theoretic method which can locate timing point at same fraction of echo pulse in pulsed time-of-flight （TOF） laser rangefinding. In this paper, the theory of CFD method was analyzed in reality condition. The design, simulation and printed-circuit-board （PCB） performance of CFD circuit were shown. Finally, an over amplified method was introduced, by which the influence of direct-current （DC） bias error could be reduced. The experimental results showed that timing discriminator could set the timing point to a certain point on echo pulse, which did not depend on the amplitude of echo pulse.

逆变电源变压器抗直流偏磁的研究

分析了在正弦波逆变电源中工频变压器产生直流偏磁原因的基础上,运用数字PI控制方法,调节触发脉冲的宽度来加以抑制。通过在逆变电源中的应用与调试,验证该方法的可行性。

44.6 fs pulses from a 257 MHz Er:fiber laser mode-locked by biased NALM

44.6 fs pulses from a 257 MHz, mode-locked non-polarization maintaining Er-doped fiber laser based on a biased nonlinear amplifying loop mirror are reported. The output power is 104 mW and the single-pulse energy is 0.4 nJ. The minimum pulse duration of the direct output is 44.6 fs, which is the shortest in this kind of laser.