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A novel floating-electrode silicon pixel detector has been proposed. The novel configuration of the floating electrode in the silicon pixel detector reduces the size of the collecting cathode and decreases both the capacitance and leakage current of the detector compared to the conventional silicon pixel detector. For the design, we used a 200 × 200 µm2 detector as the model to analyze the impact of varying numbers of floating rings on the electrical performance [Wu et al., AIP Adv. 11(2), 025315 (2021)]. We used Technology Computer Aided Design simulation to compare and analyze the simulated electric field, potential, capacitance, and breakdown voltage of the detector. The results show that decreasing the gap-to-width ratio of the floating electrode, as well as increasing the quantity of floating rings, enhances the detector's performance. [ABSTRACT FROM AUTHOR]

The behavior of a nanosecond pulsed sliding discharge plasma actuator with the ambient pressure from 27 to 101 kPa is experimentally investigated. The electric characteristics, discharge morphologies, and surface temperature distribution of the actuator supplied by constant voltages are studied under different pressure conditions. The threshold pressure for sliding discharge establishment is 54–75 kPa in this paper. The results show that the positive peak value of the current tends to increase as the pressure decreases. Time-integrated discharge images indicate that plasma luminosity and uniformity are enhanced under low-pressure conditions. The discharge morphology of the actuator at 27 kPa displays an alternating distribution of bright and dark stripes. The infrared thermal results demonstrate that decreasing the pressure increases the actuator's surface temperature, intensifies the intensity of spanwise temperature oscillations, and improves the homogeneity in the streamwise direction. [ABSTRACT FROM AUTHOR]

This letter focuses on the non-contact generation of surface acoustic waves by using a continuous wave laser moving along the sample surface. The desired large-amplitude surface acoustic waves can be generated efficiently if the laser moving speed matches the Rayleigh value, which is a typical characteristic of the continuous laser moving excitation method. The different amplitudes of surface acoustic waves were generated at different laser moving speeds, and the largest amplitude occurred when the laser moving speed approached the surface acoustic wave velocity of the material. Subsequently, the influence of laser moving distance on the wave's amplitude under Rayleigh resonance conditions was investigated. The surface acoustic waves' amplitude grew linearly with the laser's moving distance in the elastic range. In brief, this paper provides a novel method to excite large amplitude surface acoustic waves by simply changing the moving speed and moving distance of the light. [ABSTRACT FROM AUTHOR]

In this paper, a piezoelectric actuator with three symmetrical distributions is designed. Piezoelectric ceramics are polarized in a set manner. The excitation voltage signals of the same amplitude and different phases are applied to the actuator, and an elliptical trajectory is generated on the driving foot to drive the slide rail to move. Its driving principle is different from that of previous drivers of this type. For example, when moving in a certain direction, the horizontal displacement is formed by a mixture of the longitudinal vibration of one sub-actuator and the bending vibration of two sub-actuators, while the vertical displacement is generated by the bending vibration of the actuator. Through the close cooperation of the three sub-actuators, the output efficiency is greatly improved. The actuator is suitable for small high-precision control. First, the overall structure and working principle of the piezoelectric actuator are briefly introduced. Then, through the finite element analysis, the working mode with output performance and the motion track on the driving foot are analyzed. Finally, the output performance of the actuator is analyzed. When the voltage frequency is 200 Hz and the amplitude is 200 V, the maximum output speed is 5.1 mm/s and the maximum load of about 1.2 kg can be applied, which verifies that the actuator has good driving ability. [ABSTRACT FROM AUTHOR]

Traditional pixel detectors are neatly arranged rectangular or square electrodes that cover almost the entire surface. Large electrode areas lead to high capacitance, and capacitance is the primary factor affecting detector noise. A large noise signal will reduce detector detection performance and the system S/N ratio. We have designed a spiral ring electrode silicon detector cell with n-type silicon bulk and systematically studied its electrical properties, including electric potential distribution, electric field distribution, electron concentration distribution, leakage current, full depletion voltage, and detector capacitance. It has been verified that the spiral ring electrode silicon detector has a smaller capacitance than the traditional detector and a smaller depletion voltage compared with the previously designed structures such as the inner circle broom-shaped structure. At the same time, high position resolution pixel detectors can be made by the array of these detector cells. [ABSTRACT FROM AUTHOR]

In order to reduce the noise of traditional silicon pixel detectors, a new type of low-capacitance silicon pixel detector with three floating electrodes is proposed in this paper, which reduces the cathode area while keeping the volume unchanged. A TCAD simulator is used to simulate the electrical performance of the detector and obtain electrical characteristics including depletion voltage, capacitance, and leakage current. According to the results of simulation and calculation, compared with the traditional silicon pixel detector with the same volume, the capacitance of the detector without floating electrodes was reduced by 68%, the capacitance of the detector with three floating electrodes was reduced by 68%, and the leakage current was reduced by two orders of magnitude. [ABSTRACT FROM AUTHOR]

Enabling the traditional concentric silicon drift detector (CSDD) does not need an external voltage divider in the application; hence, a novel CSDD structure is proposed in this paper, in which resistor chains of equal width are deposited equally between the cathode rings and come in contact with the cathode rings. The new CSDD can achieve voltage division automatically and only needs to bias the voltage on the cathodes of the innermost ring and the outermost ring. In addition, floating cathodes were designed between the cathodes to obtain a nearly straight line drift channel and to reduce the low electric field area near the surface. The electrical properties of three types of floating cathodes (called floating cathodes of a single-ring, floating cathodes of a double-ring, and floating cathodes of a four-ring) were simulated and compared using the technology computer aided design tool. Under the field effect between the floating cathodes and the bulk, the electric field near the surface increased substantially. Moreover, the electric field near the surface of the CSDD with the floating cathodes of a double-ring changes the most uniformly so that the drift path is the straightest. [ABSTRACT FROM AUTHOR]

In this article, we describe the use of a continuous-wave laser scanning method to generate non-dispersive surface acoustic wavepackets, which propagate along the sample surface without any waveform change. To achieve this goal, a coated linear elastic film on a non-linear substrate allows for careful balancing of dispersion and non-linearity effects. The scanning speed of the laser source and the thickness of the coated film were parametrically investigated to determine the optimal scanning speed for the generation of ultrasound for a given thickness of the coated film. In the first step, four different combinations of scanning speeds and the thickness of the coated film are presented to illustrate the generation of the narrowband ultrasound. The purpose of the scanning laser source is to effectively generate large amplitude ultrasound that takes the material into the nonlinear range. Further optimization through a careful matching combination of the scanning speed and the thickness of the coated film, whereby the dispersion effect was compensated entirely by the non-linearity effect, was used to generate non-dispersive ultrasonic wavepackets, which subsequently propagate with little distortion. The main findings of the simulations indicate that non-dispersive surface acoustic wavepackets for coated systems can be generated via the scanning laser source approach for specific values of scanning speed and thickness of the coated film. [ABSTRACT FROM AUTHOR]

In this study, a novel three-dimensional trench detector structure was proposed. The detector structure includes trench electrodes and columnar electrodes. The columnar electrodes are distributed in the middle, the middle of the sides, and the four corners of the cross section of the substrate. A cross-shaped electrode is etched from top to bottom, and a polygonal trench electrode is etched from bottom to top; the bottom of the cross-shaped electrode abuts the top of the polygonal electrode. Electrical characteristics of the novel detector are simulated by Technology Computer Aided Design simulation, and we can obtain that this design reduces the area of the bottom low electric field, optimizes the electric field, and reduces the mutual interference between the cells. [ABSTRACT FROM AUTHOR]

Semiconducting molybdenum disulfide (MoS2) has drawn a lot of attention for its exceptional electronic and optoelectronic properties. Despite the potential advantages, the large contact resistance at the metal–MoS2 interfaces has been one of the biggest obstacles for the realization of ideal MoS2 transistors. One solution to improve the metal–MoS2 interfaces is to use the graphene electrodes. Here, we provide a selective etching method for fabricating graphene-contacted MoS2 transistors. It has been proved that the graphene could be totally etched with Ar+ plasma treatment, and the multilayer MoS2 flake can also be reduced layer by layer with Ar+ plasma treatment. By etching graphene selectively in graphene–MoS2 heterostructures, one can obtain graphene-contacted MoS2 transistors successfully. The transistor reported in this paper shows an on–off ratio about 106 and a carrier mobility about 42 cm2 V−1 s−1. This selective etching method would be beneficial for some other graphene-contacted electronic devices. [ABSTRACT FROM AUTHOR]

Interactions between neighboring cells often occur in a semiconductor silicon detector array. That is, there are high-energy particles incident on one cell of the detector that generate an electric signal for the cell, while weak signals are also generated in other neighboring cells. Therefore, isolation of the detector cells is an important factor in the performance of the detector, particularly for its energy resolution. To eliminate the dead space in the 3D-trench-electrode detector proposed by Brookhaven National Laboratory, a novel three-dimensional (3D) detector, the 3D-Open-Shell-Electrode Detector (3DOSED), was proposed in 2018, in which good isolation between cells was achieved. To verify this and determine the optimal structure design, a Silvaco technology computer-aided design simulation tool was used to simulate the electrical characteristics of the detector in 3D. The distributions of the electric field and the weighting field of 3DOSEDs were obtained with different opening gap angles. A single minimum ionizing particle was used that was incident vertically on the middle of the central collection electrode and peripheral trench electrode of the detector cell, according to the Ramo theorem of the principle of induced-current generation, and the mathematical software matlab was employed to calculate the induced current and carrier drift time. The interference current between the neighboring cells of a 3DOSED was obtained. Good isolation was found between neighboring cells in the 3DOSED. [ABSTRACT FROM AUTHOR]

In order to reduce dead zone of Closed Shell-Electrode Silicon Detector (CSESD), this paper introduces an optimal scheme of 3D shell electrode type detector– a novel type of Honeycomb Shell Electrode Detector– HSED (Chinese patent #zl 201710 676008.3). In this paper, we first study dead zone of the new structure and find dead zone of non-elongated HSED cell is smaller than that of CSESD. An array arrangement method of CSESD is also proposed, which makes virtually no dead zone in the array comprised by elongated detector cells. Detector electrical simulations with SILVACO TCAD, including I-V and C-V characteristic, will be given. Then, the structure with different nesting depth and dbot is simulated with SILVACO TCAD. It has been found that the closer nesting position is to the surface, the smaller dead zone is, and the deeper the nesting is, the larger the dead zone is. However, through the simulation of the weighting field, it is found that the deeper the nesting depth, the smaller the influence of the weighting field by neighboring cell. [ABSTRACT FROM AUTHOR]

In order to improve the radiation resistance of semiconductor detector, 3D trench electrode Si detector structures have been proposed by the Brookhaven National Laboratory (BNL) in 2009. In this paper, we propose a 3D trench electrode Si detector with adjustable central collection electrode, which integrates advantages of cylindrical units and parallel units. For those combined units, we use 1D Poisson equation as the first order approximation to study the changing of depletion in different regions. These results have been compared to those obtained from the full 3D simulation using a 3D-TCAD tool. According to calculations, we design a 3D trench electrode Si detector with adjustable central collection electrode. Furthermore, electrical characteristics of this type of detectors with different lengths of central collection electrode (lp+) have been simulated using the 3D-TCAD. Regarded as the main factor of signal-noise ratio, the geometric capacitance obtained from Silvaco TCAD simulations is compared with which is calculated by physical models when detectors size varies. Finally, the physic model of charge collection is established using Ramo theorem. The CCE (Charge Collection Efficiency) of detector unit is studied with this model (after Φ=1016 neq/cm2, average CCE is 38%). [ABSTRACT FROM AUTHOR]

Since the 3D-Open-Shell-Electrode Detector (3DOSED) is proposed and the structure is optimized, it is important to study 3DOSED’s electrical properties to determine the detector’s working performance, especially in the heavy radiation environments, like the Large Hadron Collider (LHC) and it’s upgrade, the High Luminosity (HL-LHC) at CERN. In this work, full 3D technology computer-aided design (TCAD) simulations have been done on this novel silicon detector structure. Simulated detector properties include the electric field distribution, the electric potential distribution, current-voltage (I-V) characteristics, capacitance-voltage (C-V) characteristics, charge collection property, and full depletion voltage. Through the analysis of calculations and simulation results, we find that the 3DOSED’s electric field and potential distributions are very uniform, even in the tiny region near the shell openings with little perturbations. The novel detector fits the designing purpose of collecting charges generated by particle/light in a good fashion with a well defined funnel shape of electric potential distribution that makes these charges drifting towards the center collection electrode. Furthermore, by analyzing the I-V, C-V, charge collection property and full depletion voltage, we can expect that the novel detector will perform well, even in the heavy radiation environments. [ABSTRACT FROM AUTHOR]

A new type of three-dimensional (3D) detector, namely 3D-Open-Shell-Electrode Detector (3DOSED), is proposed in this study. In a 3DOSED, the trench electrode can be etched all the way through the detector thickness, totally eliminating the low electric field region existed in the conventional 3D-Trench-Electrode detector. Full 3D technology computer-aided design (TCAD) simulations have been done on this novel silicon detector structure. Through comparing of the simulation results of the detector, we can obtain the best design of the 3SOSED. In addition, simulation results show that, as compared to the conventional 3D detector, the proposed 3DOSED can improve not only detector charge collection efficiency but also its radiation hardness with regard to solving the trapping problem in the detector bulk. What is more, it has been shown that detector full depletion voltage is also slightly reduced, which can improve the utility aspects of the detector. When compared to the conventional 3D detector, we find that the proposed novel 3DOSED structure has better electric potential and electric field distributions, and better electrical properties such as detector full depletion voltage. In 3DOSED array, each pixel cell is isolated from each other by highly doped trenches, but also electrically and physically connected with each other through the remaining silicon bulk between broken electrodes. [ABSTRACT FROM AUTHOR]