结构为Pt/SiNWs/n-Si/Al肖特基二极管的电子特性(英文)

采用湿化学刻蚀法直接在n-Si衬底上制备了硅纳米线(Si NWs),用无电镀法在制备好的硅纳米线上修饰Pt纳米粒子作为上电极以形成结构为Pt/Si NWs/n-Si/Al的肖特基二极管。研究了无电镀参数(如氯铂酸钾K2PtCl6浓度,无电镀时间)对结构为Pt/Si NWs/n-Si/Al的肖特基二极管电流-电压的影响。从所得的电流-电压特性曲线中提取了肖特基二极管的三个特征参数(理想因子、势垒高度以及串联电阻),并分析了这三个特征参数与无电镀参数的关系,从而确定了一个制备结构为Pt/Si NWs/n-Si/Al肖特基二极管的理想条件。研究还发现所制备的肖特基二极管理想因子大于1,势垒高度～0.67eV,与金属铂(Pt)的功函数无关,这些特性可以用巴丁模型来解释。     

III族氮化物基的肖特基势垒二极管的研制

研制了三类不同金属和III族氮化物接触的肖特基势垒二极管。测量了器件的电流-电压特性，并分析了器件偏离理想情况的原因。     

金属与半导体肖特基接触势垒模型及其载流子传输机制的研究进展

肖特基结具有整流特性,在整流器和光电检测等电子元器件制造中有极其重要的应用,重点介绍了相关研究人员在金属与半导体肖特基接触势垒的形成机理、相关数学模型及其影响因素等方面的研究进展。有研究表明,肖特基势垒的形成主要是由于费米能级的钉扎,而费米能级钉扎则源于界面新相的形成或界面极化键的存在。同时,在肖特基势垒的相关模型中,热电子激发模型是目前应用最为广泛的、用于解释界面载流子传输机制的肖特基接触势垒模型。随着对接触界面载流子传输机制的深入研究,热发射-扩散、热场发射等载流子传输机制模型相继被研究者提出。另外,相关研究表明,快速退火处理可导致肖特基接触界面处的原子扩散、重排、新相生成等现象,对肖特基接触的稳定性产生重要影响。     

GaN基LED电流加速失效机理分析

自行封装了一体化大功率白光GaN基发光二极管(LED),将LED芯片直接封装到铝板上。在室温1A下进行电流加速老化实验,通过对老化前后不同时间段器件的电学、光通量和光谱特性进行测量来分析器件的失效机理,主要分析器件的芯片和荧光粉的失效机理。器件老化前后的电学特性表明,老化过程中,器件的串联电阻和低正向偏压下的热电子发射电流增大;光通量曲线表明,LED所加驱动电压低时,多数载流子的迁移率低,复合效率高,所以在低电流测试下LED的衰减慢;光谱曲线和色温曲线表明,在老化初始阶段,荧光粉的退化很快,一段时间后蓝光芯片衰减占主导。     

金属/Hg1-xMnxTe接触的I-V特性研究

分别采用溅射和蒸发镀膜法在Hg1-xMnxTe试样表面形成了Au/Hg1-xMnxTe和Al/Hg1-xMnxTe接触,并用Aligent4155c I-V测试仪对其I-V特性进行了测量,随后对试样在10%NH4F:10%H2O2:H2O中进行了钝化处理,并对处理后的试样再次进行了I-V测量,对于测试结果用热电子发射-扩散理论进行了分析.结果表明:Au与Hg1-xMnxTe形成了良好的欧姆接触,而Al与Hg1-xMnxTe形成了具有整流特性的肖特基接触,其肖特基势垒的理论推算值为0.38eV.钝化处理后的试样,其表面漏电现象明显降低,Au/Hg1-xMnxTe接触的电流下降幅度在0.1V时最大,为76.1%;而Al/Hg1-xMnxTe接触在0.2V时最大,为93.2%.随着偏压的进一步增大,两种接触的电流减小的幅度都逐渐变小.     

Nb∶SrTiO3单晶基片上外延生长BaTiO3薄膜的漏电流机制分析

采用脉冲激光沉积法(PLD),在掺铌的钛酸锶单晶基片(Nb∶SrTiO3,NSTO)上外延生长了15nm厚度的BTO薄膜。并采用X射线衍射(XRD)、原子力显微镜(AFM)、高分辨透射电子显微镜(HRTEM)等技术,分别测试了BTO薄膜的晶相结构和微观形貌与结构,证实了薄膜的外延生长特征。以磁控溅射法制备金属铂(Pt)上电极,在室温下测试了BTO薄膜的电流-电压(I-V)曲线。通过拟合I-V曲线,结果表明:在正向电压下,薄膜的漏电流符合空间电荷受限电流机制(SCLC);在反向电压下,漏电流先为普尔-弗伦克尔发射机制(Poole-Frenkel emission),随着反向电压的升高,转变为福勒-诺德海姆隧穿机制(Fowler-Nordheim tunneling)。分析指出,在Pt/BTO界面存在一个可变的肖特基势垒,该势垒受到BTO薄膜内部迁移的氧空位影响,从而决定了上述漏电流机制。     

SnO2:F沉积的La0.67Sr0.33MnO3薄膜的电阻开关特性研究

采用脉冲激光沉积技术在SnO2:F(FTO)衬底上制备了La0.67 Sr0.33 MnO3( LSMO)薄膜.室温下利用直流电压对Au/LSMO/FTO三明治结构的器件进行了电化学测试.结果显示样品具有明显的双极性电阻开关性能.通过对I-V特性曲线进行分析,认为在高阻态时肖特基势垒和空间电荷限制电流输运机制调控.在高场区,电阻开关的高低阻态现象由电子陷阱中心分布的不对称引起的空间电荷限制电流理论来解释.     

ZnO/P-Si接触及其温度特性

用射频磁控溅射在硅衬底上淀积ZnO薄膜,随后进行I-V-T测量.实验结果显示硅基氧化锌接触具有异质结特性,异质结的电流输运机制为热发射和电流隧穿.用I-V-T测量的结果拟合计算了势垒高度和理想因子,结果发现ZnO/P-Si势垒高度随温度降低而减小理想因子则升高.异质结的这种反常的随温度变化的关系可以用肖特基势垒不均匀性理论解释.样品经Air～800℃热退火后势垒高度与未退火相比上升,说明热退火改善了氧化锌薄膜的结晶质量,减少了界面态影响.     

In0.53Ga0.47As PIN光电探测器的温度特性分析

从理论和实验上分析了双异质结In0.53Ga0.47As PIN光电探测器在不同的反向偏置电压下暗电流在甚宽温度范围内的温度特性。结果表明：在反向偏置低压与高压段,产生一复合电流与隧道电流(缺陷隧道电流与带带间隧道电流)分别占主导地位,并呈现出相应的温度特性。还从理论与实验两方面探讨了噪声对探测器R0A的影响,结果表明：在低温段,产生一复合噪声起主要作用,在高温段,俄歇复合噪声起主要作用。     

InP/GaAs低温键合的新方法

通过对 InP/GaAs 异质键合实验方法的研究,提出了包括表面活化处理、真空预键合和退火热处理的三步法,在350℃低温下实现了InP/GaAs异质材料的键合。界面电流 电压(I V)特性的研究表明,350℃样品的界面过渡层极薄,电子主要以隧穿方式通过界面,而450℃的扩散使得过渡层增厚,界面电流 电压特性可视为双肖特基二极管的反向串联。同时,对键合样品也进行了拉力测试,实验结果表明 450℃样品的键合强度优于350℃样品。最后,对InP/GaAs异质材料的键合机理进行了探讨。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.