退火对两种硅基薄膜的结构及发光影响

采用双离子束共溅射沉积方法制备了两种复合硅基薄膜SiOxCy和SiOxNy薄膜,对两种薄膜进行后退火处理,并分别对样品进行PL、FTIR、XPS谱测试分析,比较退火前后的发光及结构的变化。两种样品的光致发光测试谱(PL)表明:退火前后都有两个发光峰位-都存在470nm的发光峰位,它来自于硅基薄膜中中性氧空位缺陷(O3≡Si-Si≡O3),是由于氧原子配位的二价硅的单态-单态之间的跃迁所致,其发光强度随退火温度的升高而变化。进一步的FTIR和XPS的测试谱表明另外一个发光峰位420nm(SiOxCy薄膜)和400nm(SiOxNy薄膜)分别来自于掺杂杂质(C和N)与硅基薄膜中的Si、O组成的复合结构。而两种样品经过退火处理后掺杂所引起的发光峰位强度随退火温度的升高而增强,说明退火温度的升高有利于发光机制的形成。     

a-SiOx∶C薄膜的结构与发光特性研究

采用双离子束共溅射法制备了SiOx∶C薄膜.对样品的XRD和TEM测试结果表明薄膜为非晶结构;PL谱图显示有两个发光峰分别位于420 nm(紫光)、470 nm(蓝绿光)处;470 nm处的发光峰位来自于硅基薄膜中富硅引起的中性氧空位缺陷(O3Si-SiO3),是由与氧原子配位的二价硅的单态以及三态-单态之间的跃迁所致,而与掺碳无关.进一步的XPS测试分析表明,420 nm处的PL峰位可能来自于Si、C、O三者组成的复杂的结构.     

双离子束溅射法制备SiOxNy薄膜的结构与发光

本文采用双离子束溅射沉积法制备了SiOxNy复合薄膜,XRD、TEM测试表明薄膜呈非晶态,FTIR及XPS测试表明薄膜成分由Si、O、N组成,在室温下可观察到样品有400 nm（紫光）、470 nm（蓝光）的光致发光.根据测试分析研究了SiOxNy薄膜的可能的发光机理：470 nm处发光峰为来自于硅基薄膜中中性氧空位缺陷（O3≡Si-Si≡O3）,是由于氧原子配位的二价硅的单态-单态之间的跃迁所致,其发光强度随退火温度的升高而变化,800℃时最大,高于800℃时慢慢减弱;400 nm发光峰的发射与薄膜中的Si、O、N所形成的结构有关,它可能来自于Si、O、N结构所形成的发光中心,该峰位的强度随退火温度的升高而增强.     

Si和C共掺杂的SiO2薄膜的光致发光

采用双离子束溅射技术制备了Si和C共掺杂的SiO2薄膜,在N2气氛下进行了不同温度的退火处理。分析了样品在室温下的光致发光(PL)特性,在该样品中观察到分别位于410nm和470nm的两个发光峰。这两个发光峰的强度随着退火温度的变化呈现不同的变化趋势,表明两个发光峰的来源并不相同。用XRD和FTIR测试手段分析了样品的结构,认为470nm的发光来源于中性氧空位缺陷(O3≡Si～Si≡O3),而410nm的发光来源于Si1-xCx纳米晶粒与SiO2基质之间的界面缺陷。     

SiOx薄膜的制备及发光特性研究

本论文采用双离子束溅射沉积技术制备了非晶的SiOx薄膜，XPS的测试表明Si是以单原子或低价氧化物的形态存在于薄膜内；在波长为240nm紫外光的激发下，室温及1000℃退火后SiOx薄膜的PL谱图显示样品中存在峰位分别处于320nm，410nm，560nm，630nm四个相互分离的峰，其发光机制分别为来自中性氧空位缺陷（≡Si—O—O—Si≡）、双配位硅悬挂键（O-Si-O）、非桥氧空位中心以及其他缺陷所形成的发光中心。     

掺钼氧化锌薄膜的发光特性

使用磁控溅射法在石英基底上制备钼掺杂氧化锌薄膜.扫描电镜结果表明薄膜由晶粒大小为40～ 80 nm范围内的颗粒组成,薄膜具有六方纤锌矿型结构且沿c轴择优取向生长.在可见光范围(400～760 nm)内所有薄膜的平均光透射率超过90％.退火薄膜的光致发光(PL)光谱表明,退火处理对发光峰的位置有很大影响,随着退火温度的增加,发光峰位置从380 nm红移至400nm或从470 nm红移至525 nm.此外,钼掺杂对退火薄膜PL光谱的强度影响很大.我们认为,薄膜中缺陷浓度的变化是导致发光峰红移的主要原因,讨论了PL谱中不同的可见光的发光机制.     

退火对Cr3+离子掺杂Al2O3薄膜的结构及发光性能影响

用脉冲激光沉积技术在Si(100)基底上制备了纯Al2O3、掺杂浓度为0.3%、1%(质量分数)的Cr3+∶Al2O3薄膜。制备态的薄膜为立方γ-Al2O3结构,经800℃真空条件下退火1h样品的结晶度有所提高,呈现α-Al2O3相与γ-Al2O3相的衍射峰。薄膜基本保持了靶材中原有各元素成分比例,平均粒径为250nm,形貌为条形。与Al2O3粉体相比,制备态薄膜在386nm处的发光峰强度明显提高。这可归因于薄膜中氧空位的增加使双氧空位吸收电子所产生的F2+色心浓度提高。薄膜经真空退火后在332、398nm附近的发光峰强度明显增强,这是由于薄膜中氧空位的增加提高了F+、F色心浓度。与此同时,制备态薄膜在386nm附近发光峰经退火后由386nm蓝移至381nm,可归因于退火后制备态薄膜的内应力得到了释放。1%(质量分数)Cr3+掺杂薄膜在646、694nm出现Cr3+离子由4 T2能级跃迁至4 A2能级及由E-能级跃迁至4 A2能级产生的荧光发光峰。     

衬底温度对Zn0.85 Mg0.13 Al0.020薄膜结构和发光特性的影响

采用射频磁控溅射方法,在Si(111)基片上制备出Zn0.85Mg0.13Al0.02O薄膜。X射线衍射(XRD)证实Zn0.85Mg0.13Al0.02O薄膜为单相六角钎锌矿结构,衬底温度从室温升高到500℃,薄膜沿c轴择优生长。原子力显微镜(AFM)测量显示薄膜表面粗糙度随衬底温度的升高由9.32nm增加到19.94nm。荧光光谱仪(PL)测量显示薄膜在397nm附近有强的紫光发射,在486nm处有弱的蓝光峰,随衬底温度的升高紫峰强度提高15倍。在可见光范围内,薄膜平均透过率随衬底温度的升高由75%增加到95%,薄膜光学带隙分别为3.18,3.18和3.19eV。分析表明紫峰来自于自由激子复合,蓝峰由俘获在施主能级Zn填隙中的电子与俘获在受主能级Zn空位中的空穴复合而产生发光。     

退火温度对磁控溅射SiC薄膜结构和光学性能的影响

首先采用射频磁控溅射法在单晶Si(100)衬底上沉积制备了SiC薄膜,然后将所制备的薄膜试样分别在600,800和1 000℃氩气氛中退火120 min;采用X射线衍射仪和红外吸收光谱仪分析了薄膜的结构随退火温度的变化,采用荧光分光分度计研究了薄膜的发光性能随退火温度的变化。结果表明:室温制备的SiC薄膜为非晶态,经600℃退火后薄膜结晶,且随着退火温度的升高,薄膜的结晶程度越来越好,并且部分SiC结构发生了由α-SiC到β-SiC的转变;所制备的SiC薄膜在384和408 nm处有两个发光峰,且两峰的强度均随退火温度的升高逐渐变强,其中384nm处的峰源自于SiC的发光,408 nm处的峰源自于碳簇的发光。     

N_2O等离子体处理对富硅氮化硅薄膜发光的影响

采用PECVD方法制备富硅氮化硅(SiNx)薄膜,并研究了N2O等离子体处理对SiNx薄膜光致发光(PL)及电致发光(EL)的影响。研究结果表明,N2O等离子体处理前后SiNx薄膜的PL发光峰均位于430nm处,且强度变化不大。而其EL发光峰位于600nm处,处理后强度有所提高。但经过高温热处理后,EL强度会大幅度降低。这主要是由于N2O等离子体处理在薄膜中引入N原子,这些N原子与Si原子结合,消除Si的悬挂键,降低了非辐射复合中心的浓度;而热处理后发生的原子重排,使得N原子与Si原子断开,进而与O原子结合,致使EL强度降低。     

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.