Power dissipation characteristics of great power and super high speed semiconductor switch

The power dissipation characteristics of pulsed power switch reversely switched dynistors （RSDs） are investigated in this paper. According to the expressions of voltage on RSD, derived from the plasma bipolar drift model and the RLC circuit equations of RSD main loop, the simulation waveforms of current and voltage on RSD are acquired through iterative calculation by using the fourth order Runge-Kutta method, then the curve of transient power on RSD versus time is obtained. The result shows that the total dissipation on RSD is trivial compared with the pulse discharge energy and the commutation dissipation can be nearly ignored compared with the quasi-static dissipation. These characteristics can make the repetitive frequency of RSD increase largely. The experimental results prove the validity of simulation calculations. The influence factors on power dissipation are discussed. The power dissipation increases with the increase of the peak current and the n-base width and with the decrease of n-base doping concentration. In order to keep a low power dissipation, it is suggested that the n-base width should be smaller than 320μm when doping concentration is 1.0×10^14cm^-3 while the doping concentration should be higher than 5.8×10^13cm^-3 when n-base width is 270μm.

Analysis of the resistive switching behaviors of vanadium oxide thin film

We demonstrate the polarization of resistive switching for a Cu/VOx/Cu memory cell.The switching behaviors of Cu/VOx/Cu cell are tested by using a semiconductor device analyzer（Agilent B1500A）,and the relative micro-analysis of I-V characteristics of VOx/Cu is characterized by using a conductive atomic force microscope（CAFM）.The I-V test results indicate that both the forming and the reversible resistive switching between low resistance state（LRS） and high resistance state（HRS） can be observed under either positive or negative sweep.The CAFM images for LRS and HRS directly exhibit evidence for the formation and rupture of filaments based on positive or negative voltage.The Cu/VOx/Cu sandwiched structure exhibits reversible resistive switching behavior and shows potential applications in the next generation of nonvolatile memory.

Tetragonal Domain Switching via Reversible tm Phase Transformation

Grinding-induced tm phase transformation and the resultant texture in ceria-yttria-doped tetragonal zirconia polycrystals with varied tetragonality have been studied by XRD. It is observed that the reversible tm phase transformation occurs during grinding and the intensity ratio of I(002)t/I(200)t increases with the transformability. The author proposes that the texture induced by grinding at low temperatures is due to the tetragonal variant reorientation via cyclic,reversible tm phase transformation, termed 'transformational domain switching', instead of the ferroelastic one

Design Method of Reversely Switched Dynistor Based Pulse Circuit Without Magnetic Switch

In the reversely switched dynistor(RSD)-based pulse power circuits,a magnetic switch is usually necessary to be applied together with a main switch.It occupies space and needs a magnetic reset.In this paper,a method of designing a RSD-based pulse circuit without a magnetic switch is proposed.In the pulse circuit,a RBDT(reverse blocking diode thyristor)is used to separate the two capacitors and provide an energy branch.The pre-charge time of the RSD can be guaranteed by the energy conversion between the capacitors and inductors,instead of the saturation of the magnetic switch.In addition,the energy which is reused to trigger the RSD is based on an inductor.The pulse circuit is evaluated by simulations and practical experiments.According to the experimental results,the factors affecting the load pulse current and triggering of the RSD and RBDT are studied.Meanwhile,a method to reduce the current in the trigger switch,which is a potential problem in the pulse circuit,is proposed.

Asymmetric reversible structural switching of a diene coordination polymer promoted by UV-visible light

In natural and artificial systems,reversible reactions are commonly asymmetric with respect to the time scale and nature of the stimuli which drive the forward and backward processes.In applications for which switching behavior is required,it is desirable that the reversible reaction goes as close to symmetric as possible;however,such systems are uncommon.Herein,we report an example of ultraviolet(UV)-visible light-regulated asymmetric reversible structural switching involving a diene-based coordination polymer,CP1 and its monocyclobutane product,CP1a.It is possible to cycle at least ten times through a forward [2+2] photocycloaddition reaction and the reverse,photocleavage reaction.A single cycle can be completed within a few minutes.The transformation is accompanied by fast and distinct fluorescence changes,arising from optimisation of the reaction conditions.Density functional theory calculations allow rationalisation of the asymmetric reversible transformation between CP1 and CP1a rather than between CP1 and its dicyclobutane product CP1b.This work provides a clear illustration of reversible structural switching which approaches symmetric behaviour with respect to reaction rate and stimuli.The insights gained from this work also assist in the design of fast,reversible switching materials.

Vapor-and temperature-triggered reversible optical switching for multi-response Cu_(8)cluster supercrystals

Multi-response metal cluster supercrystal materials,which can simultaneously display various such as color,photoluminescence,changes by bearing only one stimulus,have huge potential as stimuliresponsive intelligent material,but are rarely reported.Here,we report three Cu_(8)cluster supercrystals,Cu_(8)-1,Cu_(8)-2,and Cu_(8)-3,with homologous cluster molecule units[Cu_(8)(PNP)_(3)(EPPTA)_(6)](PF_(6))_(2)but distinct packing.These supercrystals display brightμs-long photoluminescence with a high quantum yield of up to 26.6%in solid-state at room temperature and aggregation-induced emission(AIE)characteristic.Superior thermal stability and blue-excitable bright yellow emission make Cu_(8)-3 serve as a yellow phosphor for white light-emitting diode.Furthermore,upon being stimulated by solvent vapor and temperature,reversible supercrystal-to-supercrystal transformations can be witnessed accompanied by remarkable color and luminescence switching.This work not only provides a kind of Cu cluster supercrystal model but also motivates the further development of metal clusters in multi-response materials.

Thin Emitter Structure Improved Turn-on Characteristics in RSD

The thin emitter structure was introduced into reversely switched dynistor（RSD） to improve its turn-on characteristics. According to the analysis of turn-on condition, thin emitter structure is capable of reducing the extraction action for the triggering plasma layer P1 during turn-on process, and satisfying the requirement that triggering electric charge cannot be exhausted and therefore enables RSD to turn on uniformly. The on-state thin emitter RSD was equivalent to an asymmetric pin diode model. The simulation result shows that the forward voltage drop of RSD falls with the decrease of doping dose in p^＋-emitter in a certain range, and when the doping concentration is extremely tow, the decrease of the width of p^＋-emitter can obtain a tow forward voltage drop. Thin emitter RSD chips were made by sintering AI on n-Si. The test result shows that their turn-on process is uniform and the voltage drop is 7.5 V when the peak conversion current is 5 500 A.

SIMULATION OF THE MAGNETIZATION REVERSAL PROCESS OF RECTANGLE-SHAPED NiFe FILM ELEMENTS UNDER AN ORTHOGONAL MAGNETIC FIELD

The magnetization reversal process of nano-size rectangle-shaped NiFe film elements with different aspect ratios have been investigated under the orthogonally applied magnetic fields by micromagnetic simulation. Different magnetization reversal modes can appear depending on whether the bias field is applied or not. When there is no bias field, double “C” state is the initial reversal state. However, when there is a bias field, “S” state is the starting mode. The larger the aspect ratio is, the larger the switching field is. But, when the aspect ratio is larger than 3, the increase of the switching field ceases. These results can provide useful information to the application of the patterned NiFe film with rectangular elements.

Reverse mode switching of the random laser emission in dye doped liquid crystals under homogeneous and inhomogeneous electric fields

We report the observation of electric field induced random lasing in a dye doped liquid crystal system. This was achieved by using a liquid crystal host with negative dielectric anisotropy doped with laser dye PM 597 in a 75 μm cell with a homeotropic alignment layer. In the absence of an applied field, only amplified spontaneous emission was observed since the liquid crystal orientation was uniform. However, application of a field resulted in a fieldinduced planar-like configuration with local nonuniformity in liquid crystal orientation. This led to random lasing in the energized state(voltage greater than a transition threshold). The onset of lasing occurs by application of either a spatially homogenous or a spatially inhomogeneous electric field across the liquid crystal. The characteristics of the emission spectra as a function of different(i) dye concentration and(ii) applied voltage were investigated using nanosecond pulsed laser excitation at 532 nm. The effects of using an inhomogeneous field were compared to the use of a homogenous field and reported. It is shown that the spatial configuration can be used to alter the emission spectra of the system. The work is used to suggest a new configuration, referred to here as"reverse mode," for liquid crystal-based random lasers. This new configuration may provide additional avenues for their use in commercial devices.

Reversible switching between normal and thermally activated delayed fluorescence towards “smart” and single compound whitelight luminescence via controllable conformational distribution

An organic compound exhibiting simultaneously reversible switch between its emission colors and luminescence mechanisms,possessing high contrast from deep blue normal fluorescence(NF) to yellow thermally activated delayed fluorescence(TADF),is reported. Based on these two complementary colors, white-light emission combining NF and TADF from a single compound can be achieved in various states. Experimental results and density functional theory calculations indicate that the controllable conformational distribution under thermal and mechanical activation is the mechanism responsible for the reversible switching behavior.

Quantification/mechanism of interfacial interaction modulated by electric potential in aqueous salt solution

With the development of surface and interface science and technology,methods for the online modulation of interfacial performance by external stimuli are in high demand.Switching between ultra-low and high friction states is a particular goal owing to its applicability to the development of precision machines and nano/micro-electromechanical systems.In this study,reversible switching between superlubricity and high friction is realized by controlling the electric potential of a gold surface in aqueous salt solution sliding against a SiO_(2) microsphere.Applying positive potential results creates an ice-like water layer with high hydrogen bonding and adhesion at the interface,leading to nonlinear high friction.However,applying negative potential results in free water on the gold surface and negligible adhesion at the interface,causing linear ultra-low friction(friction coefficient of about 0.004,superlubricity state).A quantitative description of how the external load and interfacial adhesion affected friction force was developed,which agrees well with the experimental results.Thus,this work quantitatively reveals the mechanism of potential-controlled switching between superlubricity and high-friction states.Controlling the interfacial behavior via the electric potential could inspire novel design strategies for nano/micro-electromechanical and nano/micro-fluidic systems.