New structure GaP—GaAlP heterojunction cold cathode

A negative electron affinity (NEA) GaP-GaAlP cold cathode with a new junction structure is proposed and demonstrated by improved fabrication techniques. Emission efficiencies as high as 0.7-1.1 percent were obtained from these cathodes. The energy distribution of the emitted electrons from the cold cathode had a full width at half-maximum of about 0.3 eV. A resolution of about 500 TV lines was obtained with a sealed off 1-in vidicon tube having the cold cathode and an Sb2S3target. The electron beam temperature was about 650 K. At present, highly stable and long life NEA cold cathodes can only be obtained by improving the activation method. It is proposed that the NEA p-GaP surface can be stabilized by a Cs, Sb, and O2activation.     

Degradation of coated impregnated cathode's surface coating

The author investigates the quantitative temperature dependence on the surface coating degradation of M-type impregnated cathodes. Osmium-ruthenium coated M-type cathodes were continuously heated at four different temperatures for 2000-20000 h in vacuum apparatus with an Auger electron spectrometer (AES). The cathode surface concentration of tungsten increases with time by diffusion from tungsten base metal. The diffusion equation is solved with the boundary condition of the insulated surface and a theoretical equation is derived which represents the tungsten surface concentration. The data calculated from this equation are in very good agreement with the measured data. The activation energy obtained for a tungsten diffusion coefficient in the surface coating (osmium-ruthenium-tungsten) is 8.4 eV. It was found that the surface coating was stable during over 100000 h at cathode temperature of 1050°C_B     

Resistivity network and structural model of the oxide cathode for CRT application

In this paper, the electrical properties of oxide cathode and oxide cathode plus, supplied by LG Philips Displays, have been investigated in relation to different cathode activation regimes and methods. Oxide cathode activation treatment for different durations has been investigated. The formations of the compounds associated to the diffusion of reducing elements (Mg, Al, and W) to the Ni cap surface of oxide cathode were studied by a new suggestion method. Scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX) was used as analytical techniques. Al, W, and Mg doping elements take place during heating to 1080 K (Ni-Brightness) under a rich controlled Ba-SrO atmosphere through an acceleration life test. The chemical transport of these elements was occurred mainly by the Ni cap grain boundary mechanism with significant pile-up of Mg compounds. Al and W show a superficial concentrations and distribution. A new structural and resistivity network model of oxide cathode plus are suggested. The new structural model shows a number of metallic and metallic oxide pathways are exist at the interface or extended through the oxide coating. The effective values of the resistances and the type of the equivalent circuit in the resistivity network model are temperature and activation time dependent.     

RESEARCH ON THE EVAPORATION PROPERTY OF IMPREGNATED DISPENSER CATHODE BY AES

During the activation and ageing,the evaporation components and rates from 4.56:1.44:2impregnated dispenser cathode have been determined by the vapor-collect method based on the Augerelectron spectroscopy(AES).(1)The evaporation rate of a cathode after ageing differs from that of a justactivated cathode by a factor of 5 to 10.The evaporation energy of the former is 4.58 eV,and that of the latter is4.34 eV.(2)At operating temperature,the metallic barium in the evaporated materials is about 90%,and thebarium oxide is about 9.3%.(3)Blow 1000℃ the evaporation of Ca is not significant;over 1150℃ the Ca startsevaporating rapidly,particularly in the activation process,it may approach 3.5% at 1250℃.     

Optoelectrical characteristics of organic light-emitting devices fabricated with different cathodes

Organic light-emitting devices (OLEDs) with various cathode structures were prepared on indium tin oxide (ITO) substrates by vacuum sublimation technique, and the effects of the device cathodes on the electroluminescence (EL) characteristics of OLEDs were studied in terms of the luminance, efficiency, driving voltage and threshold voltage. The results demonstrate that the optical and electrical performance of OLEDs depend on the properties of the devices' cathodes and the characteristics of the cathode–organic interface and the organic–organic interface. The optoelectrical performance of a device with composite cathodes is better than that of the devices with metal alloy and pure metal cathodes. The improvement in the device performance can be attributed to a more efficient electron injection at the cathode–organic interface, a better balanced hole and electron recombination in the light-emitting layer and fewer accumulated charges near the organic–organic interface.     

浸渍钡钨阴极蒸发性能的AES分析

利用俄歇能谱就地定性、定量地测量了浸渍钡钨阴极(4.56∶1.44∶2)的蒸发成分和速率。得到的主要结果是:(1)老炼初期和寿命初期蒸发率可相差半个量级,前者的蒸发能为4.34eV,而后者为4.58eV;(2)蒸发物成分随阴极温度不同而变化,高温激活时,氧化钡在蒸发物中的比例缓慢减少,但Ca的蒸发增加,1250℃时,约占3.5％,在工作温度范围内,90％左右为金属钡,氧化钡约占9.3％;(3)与50年代蒸发测量相比,AES法得到的BaO蒸发量少得多,但与热力学理论计算的结果一致;(4)与AES计量的5∶3∶2,4∶1∶1阴极相比,所研究的阴极(4.56∶1.44∶2)的Ca蒸发量少得多,这是该阴极的特点;(5)逸出功测量和AST曲线都表明,当吸附了约1.51014at./cm2的钡时,多晶钨表面已建立一个由吸附原子形成的均匀的屏蔽场。     

不同转移法对碳纳米管场发射特性的影响

通过印刷法、喷涂法和电泳沉积法转移经过处理的碳纳米管(CNT)原料到ITO电极上,高温烧结制备CNT阴极阵列,并对CNT的表面形貌和场发射性能进行测试分析。结果表明,不同转移方法对CNT阴极场发射性能的影响不同,印刷法、喷涂法及电泳沉积法3种方法制备CNT阴极场发射的开启电场分别为2.21、1.62和1.85 V/μm;当电场为2.3 V/μm时,喷涂法制备的CNT阴极场发射性能最佳,电泳沉积法制备CNT阴极次之,印刷法制备的CNT阴极最差,并根据金属半导体理论分析其原因。     

Color-saturated and angle-stable blue top-emitting organic light-emitting diodes based on semitransparent bilayer cathode: Theory and experiment

Based on a modified electromagnetic theory, a bilayer metal cathode consisting of an electron injection layer and a silver (Ag) layer is designed to improve the color chromaticity in blue top-emitting organic light-emitting diodes (TEOLEDs). The effects of the complex refractive index of the electron injection material on the reflectivity and transmittivity of the bilayer cathode are investigated in detail, and then samarium (Sm) is selected as the electron injection material due to its proper refractive index of ～1.22 + 1.12i and work function of ～2.7 eV. Then, the emission peak wavelength, the full width at half maximum, and the Commission International de L’Eclairage coordinates of the blue TEOLEDs with different Sm/Ag bilayer cathodes are calculated and discussed. According to the theoretical results, a blue TEOLED with the optimized bilayer cathode of Sm (15 nm)/Ag (5 nm) is fabricated. The measurement results indicate that the blue TEOLED possesses an excellent chromaticity which is even better than that of a bottom-emitting organic light-emitting diode. Besides, the excellent angle stability is observed in the blue TEOLED even with a large viewing angle change of 0–75°.     

掺氧化钇钡钨阴极的表面特性研究

以掺氧化钇的钡钨阴极作为研究对象,利用现代表面分析技术,包括发射式电子显徽镜、扫描电子显微镜、俄歇电子谱仪和高分辨率x射线光电子谱仪等,进行了综合研究,获得了阴极发射性能、表面形貌和表面化学等实验结果,并对实验结果进行了讨论。     

一种Sc2O3掺杂Y-Gd-Hf-O压制式直热式阴极发射特性研究

为了提高Y-Gd-Hf-O阴极耐电子轰击能力,该文通过高能球磨、压制和高温氢气烧结,制备了一种Sc₂O₃掺杂Y-Gd-Hf-O压制式直热式阴极。该阴极在1550 °C工作温度下,经过10 W电子连续轰击480 h后,发射电流密度下降至初始值的87.5%,表现出良好的耐电子轰击能力。阴极表面的微观形貌、成分组成分析表明,经压制后氢气气氛烧结,阴极表面呈陶瓷状结构形态,有利于提高阴极的耐电子轰击能力;经高温烧结、激活后表面形成了n型半导体Y₂O_3-x层,对改善阴极表面导电性、降低逸出功和提高热发射有促进作用。     

微波管高温烘排时阴极温度的估算

为了估算微波管高温烘排时的阴极温度,本文提出了一种将炉温等效为热子温度的方法。采用这一方法可简便地估算出钡钨阴极及氧化物阴极在烘排时的温度。本文还对烘排炉温对阴极温度的贡献进行了讨论。     

氧作用下浸渍钡钨阴极中钙的强化表面扩散

由于探测技术上的困难,至今对铝酸钡钙扩散阴极表面钙的研究极少。本文利用低压氧锈导下Ca向阴极表面的强化扩散,并借助俄歇电子能谱仪探索了Ca的行为和作用。主要结果是:(1)相当部分Ca以金属态形式存在于钨孔隙中活性物质的近表层区;(2)钙向表面扩散的数量和速度与阴极温度、氧的暴露量成正比,它是一种界面反应驱动下的强化扩散,其激活能约为1.34eV;(3)氧作用下阴极表面氧化钙的增加是导致阴极发射衰减的重要原因,而恢复中毒的再激活机制之一,则是高温下表面钙的蒸发逸离过程。     

A Study of Scandia-Doped Pressed Cathodes

Scandia (Sc)-doped pressed cathodes were prepared by different methods, including mixing of scandium oxide and barium-calcium aluminates with tungsten by manual mechanical mixing, high-energy ball-milling, and liquid-liquid doping. The surface behavior of the active substance, microstructure, and emission properties of the cathodes has been studied by auger electron spectroscopy, scanning electron microscope, and an emission test apparatus. Results show that the cathodes prepared by the liquid-liquid doping method have a fine microstructure. This kind of cathode has a submicrometer semispherical tungsten grain structure with homogeneous distribution of Sc and barium-calcium aluminates which are dispersed over and among tungsten grains. The cathodes prepared by the liquid-liquid doping method exhibited good emission properties, e.g., the current density of this cathode reached 46 A/cm² at 850 ^degCb.     

Temperature dependence of 1/f noise in polysilicon-emitter bipolar transistors

1/f noise was measured on polysilicon-emitter bipolar n-p-n and p-n-p transistors over a temperature range of 173K相似文献   

掺Te-GaAsP中深能级缺陷和大晶格弛豫(英文)

Deep-level transient spectroscopy and photocapacitance techniques (steady -state spectroscopy, transient spectroscopy, optical isothermal transient spectroscopy and initial slope technique) have been used to study the deep-level defects in Te-doped GaAs0.8P0.4. Two electron defects(A and B center) with thermal activation energies of 0.20 and 0.40eV and photoioni-zaton threshold energies of 0.60 and 1.31eV (T = 300K) have been detected. The B center has nonexponential transient capacitance and larger difference between thermal activation energy and photoionization threshold energy. It is suggested that B center belongs to the DX center type. The relation of photoionization section spectrosopy of the B center to the temperature has been studied. It has been found that the photoionization section spectroscopy has an obvious multi-phonon-widen effect. These results support the large -lattice-relaxation model of B center. From the photoionization section spectra at eight different temperatures (104-300K), we have obtained the photoionization threshold energies (1.41-1.31eV) and the lattice relaxation energies(1.25-1.15eV) of B center, which decrease with the increasing temperature in near linear rule. A configuration coordinate diagram has been drawn to describe the large-lattice-relaxation of B center.     

Photoemission characteristics of transmission-mode negative electron affinity GaAs and (ln,Ga)As vapor-grown structures

Several types of transmission-mode negative electron affinity (NEA) photocathodes were investigated. The first group consisted of GaAs cathodes of various thicknesses grown on a composite structure composed of a GaP substrate and a Ga(As,P) buffer layer. These cathodes were of two types, one having an abrupt Ga(As,P)/GaAs interface and the other having a compositionally graded interface. The latter type exhibited the highest transmission-mode quantum efficiency, 0.11 electron per incident photon at 0.85 μm. It is assumed that the electron diffusion length L in the GaAs layer is limited by misfit dislocations arising from the lattice mismatch between the GaAs and the Ga(As,P) buffer layer. L increased with cathode layer thickness more rapidly for the graded structure, suggesting that misfit dislocation propagation into the GaAs layer is less when the dislocations are generated gradually (graded structure) than when they are introduced abruptly (ungraded structure). The second group of samples consisted of (In, Ga)As alloy cathodes of various compositions grown on both GaAs and GaP substrates with lattice-mismatch-reducing buffer layers of (In, Ga)As, (In, Ga)P, and Ga(As,P). It was found that photosensitivity was improved significantly by reducing the amount of lattice mismatch between the (In, Ga)As cathode layer and the substrate or buffer layer. Using an (In, Ga)As cathode with an (In,Ga)P buffer layer grown on a GaP substrate, transmission quantum efficiencies in excess of 0.01 were obtained over the relatively broad wavelength range of 0.7 to 1.04 µm.     

Experimental and theoretical research of electron emission mechanism of M-type cathodes

With the most advanced Synchronous Radiation Photoelectron Spectrum （SRPS）, the emission mechanism of M-type cathodes has been investigated from the perspective of chemical state. Based on the experimental results of SRPS analysis, a new model of the electron emission mechanism for M-type cathode is discussed. The main topics in this paper include the research status of electron emission mechanism of M-type cathodes; the advantages of SRPS technology; the distribution of oxygen chemical state on the cathode surface and the evolvement of oxygen chemical state during activation process; the relation between barium chemical state and osmium （Os）-coating; surplus barium and its formula; the characteristics of Os, and other noble metal coatings; the relation between film characteristics and emission performance of cathodes, the inhibition effects to the emission for Platinum （Pt）-coated cathode, etc. At the end of this paper, electron emission mechanism of M-type cathode is summarized and foreseen.     

浸渍钪酸盐钡钨阴极的次级发射特性的研究

本文利用扫描电子束探针法,研究了渍制钪酸盐钡钨阴极在室温下的次级发射特性,观察了激活程度对该阴极的次级发射特性、次级发射图象和次级发射面分布的影响。激活最佳时,可获m=3.56(Epm=700V)。在温度高于1100℃下激活,对的影响较大。该阴极表面的分布是不均匀的。面分布曲线的峰值半高宽度为0.4。本文结合国内外对该阴极表面分析研究的结果,对实验现象进行了讨论。从理论上推导出的二项式面分布曲线能与实验结果较好地符合。     

二氧化硅超薄膜的扫描隧道显微镜和扫描隧道谱研究

用超高真空热氧化方法在Si(111)清洁衬底上生长了二氧化硅超薄膜，并利用超高真空扫描隧道显微镜和扫描隧道谱技术对超薄膜的表面形貌和局域电学特性进行了研究。结果显示，在超薄范围二氧化硅呈层状生长，不同层的微分电导谱所测禁带宽度差别可以达到约3eV，形貌对二氧化硅带宽的影响小于膜厚的影响。     

无机溶胶凝胶法制备铝酸盐对钡钨阴极性能的影响研究

针对高性能、长寿命空间行波管对阴极性能的苛刻需求,本文采用一种新型无机溶胶凝胶法制备钡钨阴极用铝酸盐,利用扫描电镜、X射线衍射仪分析铝酸盐的微观形貌、物相结构,并研究不同工艺路径制备铝酸盐对阴极发射性能、蒸发性能、寿命的影响。相比固相法制备的铝酸盐及阴极,无机溶胶凝胶法制备的铝酸盐烧结温度低、结晶性好、颗粒尺寸小(约1μm)且均匀性分散;无机溶胶凝胶法制备的阴极发射得到提高,发射拐点电流密度约为32.91 A/cm2,发射斜率约为1.403(1050℃(光亮温度));阴极蒸发速率较低,为2.5×10^-10 g/cm²·s(1050℃),同时阴极寿命提高了1.43倍。