用于近贴聚焦微通道板象增强器的新颖控制电路

近贴聚焦微通道板(MCP)象增强器由于具有高的时间和空间分辨率、宽广的光谱和输入强度动态范围、高的增益以及能记录单次瞬变现象,经常被用作超高速的光快门(光闸)。 微通道板象增强器与控制其快门作用的选通脉冲发生器相结合,便构成具有高的光增益和快速响应的超高速相机。本文比较了对一个典型第二代象增强器(18mm,ITT-F4111型象增强器)进行脉冲控制的三种方式。在此基础上,提出了在象增强器的光阴极进行选通的、能产生大幅度毫微秒脉冲的新颖控制电路。实验表明,用这种控制发生器,相机的曝光时间可达到约2 ns。文中还讨论了控制发生器与象增强器之间的匹配,并提出一个简单而有效的方法,借此可以消除在单次摄影中必须绝对避免的多次曝光现象。     

Ionic Glass–Gated 2D Material–Based Phototransistor: MoSe2 over LaF3 as Case Study

Modulating the carrier density of 2D materials is pivotal to tailor their electrical properties, with novel physical phenomena expected to occur at a higher doping level. Here, the use of ionic glass as a high capacitance gate is explored to develop a 2D material–based phototransistor operated with a higher carrier concentration up to 5 × 10¹³ cm^?2, using MoSe₂ over LaF₃ as an archetypal system. Ion glass gating reveals to be a powerful technique combining the high carrier density of electrolyte gating methods while enabling direct optical addressability impeded with usual electrolyte technology. The phototransistor demonstrates I_ON/I_OFF ratio exceeding five decades and photoresponse times down to 200 µs, up to two decades faster than MoSe₂ phototransistors reported so far. Careful phototransport analysis reveals that ionic glass gating of 2D materials allows tuning the nature of the carrier recombination processes, while annihilating the traps' contribution in the electron injection regime. This remarkable property results in a photoresponse that can be modulated electrostatically by more than two orders of magnitude, while at the same time increasing the gain bandwidth product. This study demonstrates the potential of ionic glass gating to explore novel photoconduction processes and alternative architectures of devices.     

宽微带X射线分幅相机的研制

研制了应用于平焦场光栅谱仪系统的宽微带X射线分幅相机,微通道板(MCP)微带阴极的宽度为20mm,由四路选通脉冲同时驱动。分幅相机采用模块化设计,由气室、MCP变像管、电控系统、光学CCD记录系统和内嵌式计算机组成,内嵌PC104模块实现相机的远程控制。对相机进行联调实验,测得该相机的时间分辨率为71ps,空间分辨率为20lp/mm,垂直于选通脉冲传播方向的微带均匀性为1.5…1,平行于选通脉冲传播方向的微带均匀性为5.1…1。     

A 1.8-V 0.7 ppm/°C high order temperature-compensated CMOS current reference

A high order curvature compensation technique for current reference generator which exploits the I–V characteristic of MOS to achieve I _SC (T ^m ) (m ≥ 2) is described. I _SC (T ^m ) is a self-compensated current which corrects its negative three-order TC (Temperature Coefficient) and linear TC by itself. Then, I (T ²) is achieved also by exploiting the I–V characteristic of MOS, for correcting the other negative high order parts of I _SC (T ^m ). This circuit operates on a 1.8 V power supply and is compatible with a standard n-well 0.5-μm digital CMOS process. The circuit realizes a temperature coefficient of 0.7 ppm/°C, a deviation of the simulated output current of 0.011% from −20°C to + 150°C and 97.5 dB PSRR through HSPICE simulation.     

Electrically Dynamic Configurable WSe2 Transistor and the Applications in Photodetector

Non-destructive and reversible modulations of polarity and carrier concentration in transistors are essential for complementary devices. The fabricated multi-gated WSe₂ devices obtain dynamic electrostatic field induced electrically configurable functions and demonstrate as diode with high rectification ratio of 4.1 × 10⁵, as well as n- and p-type inverter with voltage gain of 19.9 and 12.1, respectively. Benefiting from the continuous band alignment induced modulation of channel underneath the dual gates, the devices exhibit high-performance photodetection in wide spectral range. The devices yield high photo-responsivity (5.16 A W⁻¹) and large I_light/I_dark ratio (1 × 10⁵). Besides, the local gate fields accelerate the separation of photo-induced carriers, leading to fast response without persistent current. This strategy takes the advantage of the simplified design and continues to deliver integrated circuits with high density. The superior electrical and photodetection characteristics exhibit great potency in the domain of future optoelectronics.     

Influence of defects formed by fast reactor neutrons on exciton luminescence spectra of cadmium sulfide single crystals

The influence of clusters of defects formed by irradiation with neutrons in CdS single crystals on parameters of the spectra of exciton photoluminescence at T ∼ 4.2 K has been studied. It is experimentally established that irradiation of the samples with fast reactor neutrons with energies E ∼ 1 MeV and dose Φ = 3 × 10¹⁸ cm⁻² brings about a decrease (by approximately 50 times) in the intensity of lines of exciton photoluminescence I ₁ (λ_m = 488.7 nm), I ₂ (λ_m = 486.9 nm), and I ₃ (λ_m = 486.3 nm) with redistribution of intensities in favor of the lines I ₁ and I ₃ and an increase in their half-width from 2 to 5–6 the positions of their peaks in the emission spectrum. Observed experimental facts are explained on the basis of a model of a two-phase system composed of slightly damaged region in the CdS single crystal in which clusters of defects (formed as a result of irradiation with neutrons) are embedded; these clusters are nanosized grains with a highly disordered structure.     

电子轰击型PSD器件的研究与应用

首先介绍了新型半导体光电位敏器件 (PSD)的独特优点。同时根据极微弱光探测的应用需求 ,提出了电子轰击型新概念器件EBPSD ,研究了它的制作原理 ,并对已制出的器件进行了半导体增益测试 ,其结果是入射电子能量 2keV时增益大于 10 2 ;5keV时增益可达 10 3 ,证实了这种器件的优越性。还将 (EB PSD)器件和微通道板相结合 ,充分利用微通道板的高增益特性 ,提出了电子增益高达 10 8的MCP PSD管设计方案 ,并制出了样管 ,指出这种器件可用于低于 10 -7lx极微弱光图像的光子计数探测     

Highly photosensitive thienoacene single crystal microplate transistors via optimized dielectric

High photosensitivity and high photocurrent gain have been obtained based on dielectric optimized dinaphtho[3,4-d:3′,4′-d′]benzo[1,2-b:4,5-b′]dithiophene (Ph5T2) single crystal microplate transistors. In our experiments, the PMMA dielectric device shows the best operational stability without hysteresis effect. Based on such an optimized device, the photoelectric properties of the Ph5T2 single crystal microplates have been studied for the first time. The Ph5T2 phototransistor has the high photosensitivity at 21 mA W⁻¹ and the extremely high photocurrent gain (I_light/I_dark) at 6.8 × 10⁵. The photocurrent gain is higher than that of the most reported organic phototransistors (OPTs), and is in a class with the highest photocurrent gain for the reported values so far. This confirms that Ph5T2 is a photosensitive material and shows it promising potential in photoswitches and phototransistors.     

An Ultrastable Aqueous Iodine-Hydrogen Gas Battery

Rechargeable hydrogen gas batteries are highly desirable for large-scale energy storage because of their long life cycle, high round trip efficiency, fast reaction kinetics, and hydrogen gas profusion. Coupling advanced cathode chemistries with hydrogen gas anode is an emerging and exciting area of research. Here, a novel high-performance aqueous iodine-hydrogen gas (I₂-H₂) battery using iodine as cathode and hydrogen gas as the electrocatalytic anode in environmentally benign aqueous electrolytes is reported. The working chemistry of the battery involves I₂/I⁻ solid-liquid reactions occurring over the cathode along with H₂/H₂O gas-liquid reactions at the anode, achieving a high rate performance of 100 C and long-lasting stability of over 60 000 cycles. Additionally, the static aqueous I₂-H₂ battery displays a volumetric capacity of 15.5 Ah L⁻¹ along with good self-healing capability towards cell overcharge. The current battery design exhibits robust electrochemical performance irrespective of acidic, neutral, and alkaline electrolyte systems. This study paves the way towards the industrialization of economically effective, high-power density, and long-term I₂-H₂ batteries for large-scale energy storage applications.     

电子束时间展宽皮秒分幅相机

研制了基于电子束时间展宽技术和微通道板（microchannel plate,MCP）选通技术的时间展宽分幅相机。相机有三条厚度80 nm、宽度8 mm的微带阴极,阴极上加载斜率为2.1 V/ps的高压斜坡脉冲,使得先发射的电子较后面的电子速度快,经过50 cm的漂移区后,电子束产生时间展宽,从而提高相机时间分辨率。阴极和MCP均加载了脉冲电压,因此,需要精确同步光脉冲、阴极脉冲和MCP选通脉冲,分析了完整的同步过程。当阴极仅加直流电压,无电子束时间展宽时,获得相机的时间分辨率为78 ps。当阴极加载高压斜坡脉冲时,电子束时间展宽技术将系统的时间分辨率提高至12 ps。改变延时,将光脉冲分别同步在斜坡脉冲不同位置,获得了时间分辨率与同步位置的关系。     

Concentration-dependent luminescence properties in Er3+-doped TeO2-ZnO-La2O3 glasses

Erbium-doped tellurite-based glasses(Er3+:TeO2-ZnO-La2O3) are prepared by the conventional melt-quenching technique,and concentration-dependent luminescence properties of Er3+ are investigated.A significant spectral broadening of the 1.53 μm fluorescence corresponding to 4I13/2 →4I15/2 transition is observed,and the fluorescence decaying becomes a nearly exponential way with the increasing Er3+concentration.Radiation trapping is evoked to explain the broadening of 4I13/2 → 4I15/2 emission line of Er3+ ions.The optimum doping content of Er2O3 for 1.53 μm fluorescence emission is about 1.5 mol%.     

Low-frequency noise in n-GaN

Low-frequency noise has been investigated in the hexagonal polytype of n-type gallium nitride (GaN) with equilibrium electron concentration at 300 K n ₀⋍7×10¹⁷ cm⁻³. The frequency and temperature dependence of the noise spectral density S _I/I² was studied in the range of analysis frequencies f from 20 Hz to 20 kHz in the temperature range from 80 to 400 K. Over the entire temperature range the frequency dependence of the dark noise is close to S _I/I²∼1/f (flicker noise). The rather weak temperature dependence of the noise level is characterized by very high values of the Hooge constant α⋍5–7. These large α values indicate a rather low level of structural quality of the material. The effects of infrared and band-to-band illumination on low-frequency noise in GaN are studied here for the first time. The noise level is unaffected by illumination with photon energy E _ph<E _g (E _g is the band gap) even for a relatively high value of the photoconductivity Δσ⋍50%. Band-to-band illumination (E _ph⩾E _g) influences the low-frequency noise level over the entire investigated temperature range. At relatively high temperatures the influence of illumination is qualitatively similar to that of band-to-band illumination on low-frequency noise in Si and GaAs. At relatively low temperatures the influence of illumination on the noise in GaN is qualitatively different from the results obtained earlier for Si and GaAs. Fiz. Tekh. Poluprovodn. 32, 285–289 (March 1998)     

Microchannel plate inverter image intensifiers

The characteristics of microchannel plate/inverter image intensifiers (MCP/III) are described. This type of image tube is shown to be well suited to some night vision applications. The 25 mm MCP/III developed by the authors has a minimum magnification of 0.96, a maximum distortion of 5 percent, and a limiting resolution of 10 cycles/mm. Its luminance gain is about 10⁵at input levels up to 2 × 10^-3fc when an S20 photocathode and a P20 phosphor screen are employed. The operational life of a MCP/III is generally a few thousand hours. Accurate life data can be determined, for a given application, after the operating input light level value, the applied MCP potential, and the duty cycle are established. The unique bulb design allows the tube high voltage power supply to be placed around the tube envelope within a 50 mm diameter and reduces the total interelectrode capacitance of the gating/focus electrode to 7 pF.     

Gated IR Imaging with 128 × 128 HgCdTe Electron Avalanche Photodiode FPA

The next generation of infrared (IR) sensor systems will include active imaging capabilities. One example of such a system is a gated active/passive system. The gated active/passive system promises target detection and identification at longer ranges compared to conventional passive-only imaging systems. A detector that is capable of both active and passive modes of operation opens up the possibility of a self-aligned system that uses a single focal plane. The mid-wave infrared (MWIR) HgCdTe electron injection avalanche photodiode (e-APD) provides state-of-the-art 3 μm to 5 μm performance for the passive mode and high, low-noise, gain in the active mode, and high quantum efficiency at 1.5 μm. Gains of greater than 1000 have been measured in MWIR e-APDs with a gain-independent excess noise factor of 1.3. This paper reports the application of the mid-wave HgCdTe e-APD for near-IR gated-active/passive imaging. Specifically a 128 × 128 focal-plane array (FPA) composed of 40-μm-pitch MWIR cutoff APD detectors and custom readout integrated circuit was designed, fabricated, and tested. Median gains as high as 946 at 11 V bias with noise equivalent photon inputs as low as 0.4 photon were measured at 80 K and 1 μs gate times. This subphoton sensitivity is consistent with the high gains, low excess noise factor, and low effective gain normalized dark-current densities, near or below 1 nA/cm², that were achieved in these FPAs. A gated imaging demonstration system was designed and built using commercially available parts. High resolution and precision gating was demonstrated in this system by imagery taken at ranges out to 9 km.     

A low-distortion CMOS IF VGA with linear-in-dB control and temperature compensation

A CMOS intermediate-frequency (IF) variable-gain amplifier (VGA) is presented in this paper. A transconductance linearization scheme is proposed for the VGA core based on a signal-subtracting structure to achieve low distortion. Temperature-independent decibel-linear gain control characteristic is achieved by an exponential voltage generator based on transfer characteristics of differential pair. The whole VGA, including a highly-linear output stage, is fabricated in 0.25 μm CMOS technology. Measurements show that the VGA provides a total gain control range of 43 dB with less than 1.2 dB error over 0–80°C, and a constant 3-dB bandwidth of 100 MHz. The third-order intermodulation (IM3) distortion at differential output of 2 V_PP is better than −55 dB. The VGA dissipates 22.6 mA averagely from 3.3 V supply, and occupies approximately 0.53 mm².     

The principle of design for double injection Ge magneto-diode

 design principle is propose for long.P~+IN~+Ge magneto-diode with a high surface recombination region on one side.The optimal relation is established for design among its length l,depth d,width w and resistivity p: where ⊿T is the maximum permissible temperature rise of the chip,R_(th)the thermal resistance of the header,I_o the forward current of the diode.     

Conductivity of layers of a chalcogenide glassy semiconductor Ge<Subscript>2</Subscript>Sb<Subscript>2</Subscript>Te<Subscript>5</Subscript> in high electric fields

Effect of high electric fields on the conductivity of 0.5-1-μm-thick layers of a chalcogenide glassy semiconductor with a composition Ge₂Sb₂Te₅, used in phase memory cells, has been studied. It was found that two dependences are observed in high fields: dependence of the current I on the voltage U, of the type I ∝ U ⁿ , with the exponent (n ≈ 2) related to space-charge-limited currents, and a dependence of the conductivity σ on the field strength F of the type σ = σ₀exp(F/F ₀) (where F ₀ = 6 × 10⁴ V cm⁻¹), caused by ionization of localized states. A mobility of 10⁻³–10⁻² cm² V⁻¹ s⁻¹ was determined from the space-charge-limited currents.     

The effect of current suppression in the pn−n+ diode of integrated injection logic

The j-V characteristics of the pn^?n⁺ diode are derived by combining the different current components in the n^? region of the diode for various bias voltages. For infinitly fast recombination, the expression for the current density as a function of bias reduces to that of a conventional one-dimensional theory. For finite recombination, however, the expression deviates significantly from the usual expression. In fact, contrary to what would be expected from the conventional theory, the current increases as the width of the neutral n^? region increases for a constant bias. Finally the results of the analysis of the pn^?n + diode are applied to an analysis of the current gain in the integrated injection logic (I²L) device. A qualitative discussion of the current gain for the lateral pnp transistor and for that of the vertical npn transistor is given.     

Toward Shuttle-Free Zn–I2 Battery: Anchoring and Catalyzing Iodine Conversion by High-Density P-Doping Sites in Carbon Host

Zn–iodine (I₂) battery, as a promising energy storage device, especially under high I₂ loading, is harassed by the shuttle effect of the soluble polyiodide intermediates. Herein, the bifunctional role of 2D carbon nanosponge with rich P-dopant (4.2 at%) and large specific surface area (1966 m² g⁻¹) in anchoring I₂/I_x⁻ (x = 1, 3 or 5) and catalyzing their mutual conversion is reported. Both experiment and computational results reveal the transfer of electrons from the P-doped site to iodine species, showing strong interfacial interaction. When being used as a host, it possesses high specific capture capacity for I₂ (3.34 g_iodine g⁻¹ or 1.6 mg_iodine m⁻²) and I_x⁻ (6.12 g_triiodide g⁻¹ or 3.1 mg_triiodide m⁻²), which thus effectively suppresses the shuttle effect, supported by in situ UV–vis and Raman spectra. In addition to the strong interfacial interaction that favors iodine conversion, the P-doped sites can also catalyze the conversion of I₅⁻ to I₂, which is the rate-determining step. Consequently, Zn–I₂ batteries under a high I₂ content (70 wt%) deliver high specific capacity (220.3 mAh g⁻¹), superior Coulombic efficiency (>99%), and low self-discharge rate; moreover, they can also operate steadily at 2 A g⁻¹ with ignorable capacity decay for 10 000 cycles.     

Porous Metal–Organic Framework@Polymer Beads for Iodine Capture and Recovery Using a Gas‐Sparged Column

Iodine (I₂) capture and recovery is an important process in many industrial practices. Conventional materials for I₂ capture include Ag⁰‐based aerogels and zeolites and C‐based aerogels and powders, which suffer from expensive and/or inefficient recovery. Recently, metal–organic frameworks (MOFs) have shown potential as good adsorbents for I₂ capture with high capacity, fast uptake, and good recyclability. The powder form of MOFs, however, often makes them impractical in large‐scale applications. Herein, a versatile method based on the phase inversion technique is presented to fabricate millimeter‐sized spherical MOF@polymer composite beads, and the use of these beads for I₂ capture and recovery is demonstrated. Besides preserving the crystallinity and pore accessibility of the embedded MOFs in the polymeric matrix, the beads exhibit higher capacity and faster uptake rate for I₂ in both vapor and liquid phases compared to the bulk MOF powder. In order to showcase the applicability of these beads, a gas‐sparged column is used as a proof‐of‐concept device that can efficiently capture and recover more than 99% of I₂ from the feeding solution. The beads can be recycled and reused multiple times, which in combination with their easy handling and storage highlights their superiority compared to MOF powders in adsorption applications.