薄栅氧化层斜坡电压TDDB寿命评价

随着超大规模集成电路的不断发展,薄栅氧化层的质量对器件和电路可靠性的作用越来越重要。经时绝缘击穿(TDDB)是评价薄栅氧化层质量的重要方法。文章着重于薄栅氧化层TDDB可靠性评价的斜坡电压试验方法的研究,基于斜坡电压实验,提取模型参数,分别利用线性场模型和定量物理模型,外推出工作电压下栅氧化层的寿命。通过分析斜坡电压实验时氧化层的击穿过程,提出斜坡电压实验时利用统一模型外推栅氧化层的寿命比较合适。

薄栅氧化层斜坡电压TDDB击穿参数的研究

随着超大规模集成电路的不断发展,薄栅氧化层的质量对器件和电路的可靠性的作用越来越重要。经时绝缘击穿(TDDB)是评价薄栅氧化层质量的重要方法。本次实验主要是通过斜坡电压实验来研究薄栅氧化层的TDDB,测出斜坡电压时氧化层的击穿电压、击穿电荷以及击穿时间,研究了斜坡电压情况下,栅氧化层击穿电荷、击穿电压和外加电压斜率等击穿参数间的依赖关系。

Freestanding oxide membranes:synthesis,tunable physical properties,and functional devices

The study of oxide heteroepitaxy has been hindered by the issues of misfit strain and substrate clamping,which impede both the optimization of performance and the acquisition of a fundamental understanding of oxide systems.Recently,however,the development of freestanding oxide membranes has provided a plausible solution to these substrate limitations.Single-crystalline functional oxide films can be released from their substrates without incurring significant damage and can subsequently be transferred to any substrate of choice.This paper discusses recent advancements in the fabrication,adjustable physical properties,and various applications of freestanding oxide perovskite films.First,we present the primary strategies employed for the synthesis and transfer of these freestanding perovskite thin films.Second,we explore the main functionalities observed in freestanding perovskite oxide thin films,with special attention to the tunable functionalities and physical properties of these freestanding perovskite membranes under varying strain states.Next,we encapsulate three representative devices based on freestanding oxide films.Overall,this review highlights the potential of freestanding oxide films for the study of novel functionalities and flexible electronics.

双极电路欧姆接触问题的工艺分析与解决方案

为解决一种双极集成电路在生产中欧姆接触电阻过大的问题,针对关键工艺进行了统计分析和专项实验,找到了问题的原因和解决方法,对提高大规模集成电路的工艺制造稳定性具有非常重要的意义。

ANALYSES OF WAGNER'S MODEL

To achieve a better understanding of the effects of the colossal magnetoresistivity in the mixed valence manganites,the model of a negative magnetoresistivity scaling proposed by Wagner et al is explored in both mathematical and physical analyses.The inconsistency in Wagners model is discussed and corrected. The behaviors of the large spin polarons in Nd 0.52 Sr 0.48 MnO 3 film at T c are studied and analyzed.The results show that only through necessary corrections can Wagners model become self consistent. A further exploration of the nature of the magnetically aligned clusters will make the model more convincing.

Crystallization Behavior and Properties of B-Doped ZnO Thin Films Prepared by Sol-Gel Method with Different Pyrolysis Temperatures

Boron-doped zinc oxide transparent （BZO） films were prepared by sol-gel method. The effect of pyrolysis temperature on the crystallization behavior and properties was systematically investigated. XRD patterns revealed that the BZO films had wurtzite structure with a preferential growth orientation along the c-axis. With the increase of pyrolysis temperature, the particle size and surface roughness of the BZO films increased, suggesting that pyrolysis temperature is the critical factor for determining the crystallization behavior of the BZO films. Moreover, the carrier concentration and the carrier mobility increased with increasing the pyrolysis temperature, and the mean transmittance for every film is over 90% in the visible range.

Preparation of High Quality Indium Tin Oxide Film on a Microbial Cellulose Membrane Using Radio Frequency Magnetron Sputtering

Microbial cellulose （MC） membranes produced by Acetobacter xylinum NUST4.1,were used as flexible substrates for the fabrication of transparent indium tin oxide （ITO） electrodes.Transparent and conductive ITO thin films were deposited on MC membrane at room temperature using radio frequency （RF） magnetron sputtering.The optimum ITO deposition conditions were achieved by examining crystalline structure,surface morphology and op-toelectrical characteristics with X-ray diffraction （XRD）,scanning electron microscopy （SEM）,atomic force mi-croscopy （AFM）,and UV spectroscopy.The sheet resistance of the samples was measured with a four-point probe and the resistivity of the film was calculated.The results reveal that the preferred orientation of the deposited ITO crystals is strongly dependent upon with oxygen content （O2/Ar,volume ratio） in the sputtering chamber.And the ITO crystalline structure directly determines the conductivity of ITO-deposited films.High conductive [sheet resis-tance ～120 Ω·square-1 （Ω·sq-1）] and transparent （above 76%） ITO thin films （240 nm thick） were obtained with a moderate sputtering power （about 60 W） and with an oxygen flow rate of 0.25 ml·min-1 （sccm） during the deposi-tion.These results show that the ITO-MC electrodes can find their potential application in optoelectrical devices.

Surface characteristics and structure of oxide films containing Ca and P on Ti substrate

The oxide films were obtained in an electrolyte of calcium glycerphosphate (Ca-GP) and calcium acetate (CA) by microarc oxidation (MAO). The oxide films displayed a porous and rough structure on the film surface, and the roughness tended to increase with increasing voltage of microarc oxidation. The oxide film exhibited a uniform coating and tends to be well boned to the substrate. The thickness of oxide films depended on the final voltage at a constant concentration of electrolyte solution. Ca and P were also incorporated into the oxide film during the microarc oxidation process. It was found that the electrolyte of calcium glycerphosphate (Ca-GP) and calcium acetate (CA) was suitable for microarc oxidation to form oxide film containing Ca and P on Ti substrate. The concentration of Ca and P were 11.6 at% and 6.4 at%, respectively, when microarc oxidation was performed in the electrolyte of 0.06 M Ca-GP and 0.25 M CA at current density 50 A/m^2 and final voltage 350 V. The composition of the Ca, P and Ti changed during depth profiling. The crystalline phases were only anatase when final voltage was below 300 V and rutile was presented when voltage was up to 350 V. The microstructure, phase structure and phase composition were investigated by scanning electron microscopy (SEM), atomic force microscope (AFM), energy dispersive X-ray microanalyser (EDX), and X-ray diffraction (XRD).

Optical and electrical properties of room temperature preparedα-IGZO thin films using an In_(2)Ga_(2)ZnO_(7) ceramic target

In this study,a high-purity In_(2)Ga_(2)ZnO_(7) ceramic target was used to deposit indium gallium zinc oxide(IGZO)films by RF magnetron sputtering technology.The microstructure,growth state,optical and electrical properties of the IGZO films were studied.The results showed that the surface of the IGZO film was uniform and smooth at room temperature.As the substrate temperature increased,the surface roughness of the film gradually increased.From room temperature to 300℃,all the films maintained amorphous phase and good thermal stabilities.Moreover,the transmission in the visible region decreased from 91.93%to 91.08%,and the band gap slightly decreased from 3.79 to 3.76 eV.The characterization of the film via atomic force microscope(AFM)and X-ray photoelectron spectroscopy(XPS)demonstrated that the film prepared at room temperature exhibited the lowest surface roughness and the largest content of oxygen vacancies.With the rise in temperature,the non-homogeneous particle distribution,increase in the surface roughness,and reduction in the number of oxygen vacancies resulted in lower performance of theα-IGZO film.Comprehensive analysis showed that the best optical and electrical properties can be obtained by depositing IGZO films at room temperature,which indicates their potential applications in flexible substrates.

Composition change and capacitance properties of ruthenium oxide thin film

Ru O2·n H2O film was deposited on tantalum foils by electrodeposition and heat treatment using Ru Cl3·3H2O as precursor.Surface morphology, composition change and cyclic voltammetry from precursor to amorphous and crystalline RuO2·n H2O films were studied by X-ray diffractometer, Fourier transformation infrared spectrometer, differential thermal analyzer, scanning electron microscope and electrochemical analyzer, respectively. The results show that the precursor was transformed gradually from amorphous to crystalline phase with temperature. When heat treated at 300 °C for 2h, RuO2·n H2O electrode surface gains mass of2.5 mg/cm2 with specific capacitance of 782 F/g. Besides, it is found that the specific capacitance of the film decreased by roughly20% with voltage scan rate increasing from 5 to 250 m V/s.

Tradeoffbetween Narrowing Optical Band Gap and Enhancing Electrical Conductivity of the Metal Nanoparticles-Modified Titanium Oxide Films

The n-type semiconducting titanium oxide thin films are well-known as electron transporting interlayer in photovoltaic cells. The favorable characteristics of interlayers in photovoltaics are high optical transmittance （T%）, wide band gap energy （Eg） and high electrical conductivity （σ）. Modifying titanium oxide films with metal nanoparticles would increase electrical conductivity but reduce optical band gap energy. We developed the sol-gel derived titanium suboxide （TiOx） films modified with silver （Ag） or gold （Au） or copper （Cu） nanoparticles （NPs）. This study explores a tradeoff between narrowing optical band gap and enhancing electrical conductivity of nanostructured TiOx films by controlling the Au- or Ag- or Cu-NPs loading concentrations （mol%） in titania. The Au- and Cu-NPs loading concentration of 4 mol% should meet a tradeoff which yields the higher T%, wider Eg and higher compared to those of pure TiOx films. In addition, since the pure Cu is not thermodynamically stable in ambience as compared to Au and Ag, the stability of as-obtained colloidal CuNPs is also examined. A careful examination of the time evolution of surface plasmon resonance （SPR） bands of CuNPs indicates that their stability is only up to 4 h.

Self-Organizing Evolution of Anodized Oxide Films on Ti-25Nb-3Mo-2Sn-3Zr Alloy and Hydrophilicity

In the present work,hierarchical nanostructured titanium dioxide(TiO2) films were fabricated on Ti-25Nb-3Mo-2Sn-3Zr(TLM) alloy for biomedical applications via one-step anodization process in ethylene glycolbased electrolyte containing 0.5wt% NH4F.The nanostructured TiO2 films exhibited three distinct types depending on the anodization time:top irregular nanopores(INP)/beneath regular nanopores(RNP),top INP/middle regular nanotubes(RNT)/bottom RNP and top RNT with underlying RNP.The evolution of the nanostructured TiO2 films with anodization time demonstrated that self-organizing nanopores formed at the very beginning and individual nanotubes originated from underlying nanopore dissolution.Furthermore,a modified two-stage self-organizing mechanism was introduced to illustrate the growth of the nanostructured TiO2 films.Compared with TLM titanium alloy matrix,the TiO2 films with special nano-structure hold better hydrophilicity and higher specific surface area,which lays the foundation for their biomedical applications.

Obtaining Thin Film of SnO2/Cu2O and Characterization by X-Ray Diffraction

Thin films of tin and copper oxide forming heterojunction are being studied for applications in photovoltaic systems. The procedure for obtaining such a film was based on the technique of spray pyrolysis with working temperature of 600 ℃. The XRD （X-ray diffraction） showed the formation of tin oxides （SnO2） and copper （Cu2O） and its structural parameters are a, b and c, 4.7534 A^°, 4.7534 A^°, 3.1998 A^° （tetragonal form） and 4.2580 A^°, 4.2580 A^°, 4.2580 A^° （cubic form）, respectively. Highseore Plus program was used for phase identification and DBWSTool2.4 program used for refinement. The grain size was estimated by Williamson-Hall.

Nodeless pairing in superconducting copper-oxide monolayer films on BieSreCaCueO8＋δ

The pairing mechanism of high-temperature superconductivity in cuprates remains the biggest unresolved mystery in condensed matter physics. To solve the problem, one of the most effective approaches is to investigate directly the superconducting CuO2 layers. Here, by growing CuO2 monolayer films on Bi2Sr2CaCu2O8＋δ substrates, we identify two distinct and spatially separated energy gaps centered at the Fermi energy, a smaller U-like gap and a larger V-like gap on the films, and study their interactions with alien atoms by low-temperature scanning tunneling microscopy. The newly discovered U-like gap exhibits strong phase coherence and is immune to scattering by K, Cs and Ag atoms, suggesting its nature as a nodeless superconducting gap in the CuO2 layers, whereas the V-like gap agrees with the well-known pseudogap state in the underdoped regime. Our results support an s-wave superconductivity in Bi2Sr2CaCu2O8＋δ, which, we pro- pose, originates from the modulation-doping resultant twodimensional hole liquid confined in the CuO2 layers.

Polyvinylpyrrolidone/graphene oxide thin films coated on quartz crystal microbalance electrode for NH_3 detection at room temperature

In this paper, composite film based on polyvinylpyrrolidone(PVP)/graphene oxide(GO) was fabricated by spray method on AT-cut 9.986 MHz quartz crystal microbalance(QCM) for NH_3 sensing. The thin films were characterized by scanning electron microscope(SEM), Fourier transform infrared spectroscopy(FTIR) and ultraviolet-visible spectroscopy(UV-VIS) to investigate the morphologies and the composition contents, respectively. The experimental results reveal that PVP/GO based sensor holds higher sensitivity, larger responsiveness and smaller baseline drift than those based on pure PVP at room temperature. Besides, the prepared sensor exhibits greater response to NH_3 than other gases such as CO, CO_2 and NO_2 at the same concentration. The good linearity, reproducibility and stability demonstrate the practicability of PVP/GO hybrid film in detecting NH_3.

A Novel Approach to Predict the Stability Limits of Combustion Chambers with Large Eddy Simulation

Lean premixed combustion,which allows for reducing the production of thermal NOx,is prone to combustion instabilities.There is an extensive research to develop a reduced physical model,which allows-without time-consuming measurements-to calculate the resonance characteristics of a combustion system consisting of Helmholtz resonator type components (burner plenum,combustion chamber).For the formulation of this model numerical investigations by means of compressible Large Eddy Simulation (LES) were carried out.In these investigations the flow in the combustion chamber is isotherm,non-reacting and excited with a sinusoidal mass flow rate.Firstly a combustion chamber as a single resonator subsequently a coupled system of a burner plenum and a combustion chamber were investigated.In this paper the results of additional investigations of the single resonator are presented.The flow in the combustion chamber was investigated without excitation at the inlet.It was detected,that the mass flow rate at the outlet cross section is pulsating once the flow in the chamber is turbulent.The fast Fourier transform of the signal showed that the dominant mode is at the resonance frequency of the combustion chamber.This result sheds light on a very important source of self-excited combustion instabilities.Furthermore the LES can provide not only the damping ratio for the analytical model but the eigenfrequency of the resonator also.

Freestanding macroscopic metal-oxide nanotube films derived from carbon nanotube film templates

Aligned carbon nanotube films coated with amorphous carbon were developed into novel templates by atomic layer deposition. Freestanding macroscopic metal-oxide nanotube films were then successfully synthesized by using these templates. The reactive amorphous carbon layer greatly improved the nuclei density, which ensured the high quality of the films and allowed for precise control of the wall thickness of the nanotubes. Using template-synthesized alumina nanotube films, we demonstrate a humidity sensor with a high response speed, a transmission electron microscopy （TEM） grid, and a catalyst support. The cross- stacked assembly, ultrathin thickness, chemical inertness, and high thermal stability of the alumina nanotube films contributed to the excellent performance of these devices. In addition, it is expected that the metal-oxide nanotube films would have significant potential owing to their material richness, macroscopic appearance, flexibility, compatibility with the semiconducting technologies, and the feasibility of mass production.

Preparation and properties of solution-processed zinc tin oxide films from a new organic precursor

Transparent,smooth and dense zinc tin oxide (ZTO) thin films have been successfully produced by using a new precursor solution,zinc acetate and tin(II) 2-ethylhexanoate mixed with 2-ethanolamine in methoxyethanol.The ZTO films have been prepared by spin-coating,followed by thermal treatment in oxygen atmosphere.The morphology,composition,crystallinity and band gap energy (Eg) of the ZTO thin films have been characterized by Atomic Force Microscopy (AFM),Atomic Emission Spectrometry (AES),X-ray Diffraction (XRD) and UV-vis spectrophotometry.The conductivity of ZTO is about 9.8×10-9 S/cm,as estimated from the current-voltage (I-V) curve.The effect of the thermal treatment process on the morphology of ZTO thin films is also discussed.

Transparent conductive reduced graphene oxide thin films produced by spray coating

Reduced graphene oxide thin films were fabricated on quartz by spray coating method using a stable dispersion of reduced graphene oxide in N,N-Dimethylformamide.The dispersion was produced by chemical reduction of graphene oxide,and the film thickness was controlled with the amount of spray volume.AFM measurements revealed that the thin films have near-atomically flat surface.The chemical and structural parameters of the samples were analyzed by Raman and XPS studies.It was found that the thin films show electrical conductivity with good optical transparency in the visible to near infrared region.The sheet resistance of the films can be significantly reduced by annealing in vacuum and reach 58 k?with a light transmittance of 68.69%at 550 nm.The conductive transparent properties of the reduced graphene oxide thin films would be useful to develop flexible electronics.

Exchange coupling-induced uniaxial anisotropy in La_(0.7)Sr_(0.3)MnO_3 thin films

Establishing a deeper understanding of the anisotropy in manganites is useful for tailoring their magnetic properties for device applications. Here we showed that ferromagnetic La_(0.7)Sr_(0.3)MnO_3(LSMO) thin films,epitaxially grown on SrTiO_3(STO) substrates, exhibited unexpected double-shifted magnetization curves originating from the competition between common biaxial and emergent uniaxial anisotropies. This emergent uniaxial anisotropy could be induced by exchange coupling between the ferromagnetic LSMO and an antiferromagnetic LSMO dead layer at the LSMO/STO interface, which could be manipulated by the degree of oxygen deficiency.