基于光响应的林一草模式冠层郁闭度研究

模拟设计5个不同遮荫梯度,运用Li-6400便携带式光合测定仪从扁穗牛鞭草光响应生理的角度对林草模式植被恢复后冠层郁闭度大小控制进行了初步探索.结果表明:强度较大的60％和79％的遮荫下扁穗牛鞭草的最大净光合速率分别约为全光照的44.3％和42.5％,表观光合量子速率相对较小,对低光照不敏感,不适应此遮荫环境;遮荫16...     

Effect of temperature on carrier transport and photoconductivity of Mn-doped FeS2 thin films

Thin-film of Mn-doped iron disulfide (FeS₂) has been prepared using the thermal evaporation method. This work reports the Hall measurements, temperature and light intensity-dependent photoconductivity, electrical transport mechanism, and photodetection properties of Mn-doped FeS₂ thin film. The transient photoconductivity measurements of p-type Mn-doped FeS₂ thin film show a consistent dependence upon temperature and light intensity. Charge transport mechanism was illustrated using different models. In region-I (303–393 ?K) deposited film followed the thermally activated transport mechanism. Nearest neighbour hopping (NNH) transport mechanism was followed by region-II (274–293 ?K), and Mott's variable range hopping (VRH) mechanism was dominant in region-III (108–273 ?K). The fabricated device resulted in higher photoconductivity due to collecting charge carriers through electrodes under light illumination. The results also revealed that Mn-doped thin film possessed good photoresponsivity (～19 ?mA/W) as well as photo-detectivity (～3.4 ?× ?10¹² Jones) due to the occupation of localized states formed by Mn-doping. Light intensity-dependent photodetection properties suggested the potential for real-time photodetection applications.     

铝诱导晶化非晶硅薄膜研究

应用晶化非晶硅（a—Si）薄膜铝诱导方法，采用X射线衍射（X-ray diffraction，XRD）、光学显微镜（Optical Microscopy，OM）和原子力显微镜（Atomic Force Microscopy，AFM）等测试手段，研究了退火条件对样品晶化的影响．结果表明，样品在300℃下退火后仍为非晶态；退火温度为400℃时，样品开始晶化．随着退火时间的增加，薄膜晶化程度越来越高，晶粒越来越大，同时薄膜表面粗糙度增加．     

沉积温度对微晶硅薄膜结构特性的影响

采用PECVD技术,在玻璃衬底上沉积μc-Si:H薄膜.用拉曼光谱、SEM和UV分光光度计对不同沉积温度下沉积的薄膜的结构特性进行分析.研究发现:沉积温度较低时,随着沉积温度的升高,薄膜的晶化率增加;当沉积温度超过某一温度值时,随着温度的进一步升高,薄膜的晶化率降低.这时,表面反应由表面扩散限制转变为流量控制.该温度值随着硅烷含量的降低而降低.     

Recent development of organic electron transport materials

This article reviews the recent development of organic electron transport materials applied in the fields of organic photoconductors, light-emitting diodes, field-effect transistors and solar cells. Several technologies for charge carrier mobility measurement are summarized and compared, and a series of basic principles for designing high-performance organic electron transport materials are suggested as well.     

液化汽船、油船、集装箱船运输效率的量化分析

通过对船舶运输效率及其基本理论的分析,结合液化汽船、油船、集装箱船的发展历程,量化分析海上运输效率的发展进程,试图找出船舶运输的发展趋势.     

在不停机情况下测试图像和伴音载频的间距

如何对电视信号的两个重要频率-图像载频和伴音载频的间距及其稳定度进行监督与测试,是广播电视的一个重要问题。传统的方法是分别测试这两个频率再求其差,其缺点是测量误差较大。本文提出一种在线测试技术方案,既能高精度地测量与监视图像/伴音间距和稳定度,又不中断电视节目的发送,详细地说明了测试步骤、建议了仪器设定、给出了实验结果,对本方案进行了科学的验证。     

金属量子结构中的半导体输运性质及其调控

随着后摩尔时代的推进,以硅为基础的半导体器件正接近其性能极限.除了不断引入新的器件结构外,设计具有半导体特性的金属量子结构为微电子器件的性能提升提供了全新的解决方案;而打开金属带隙,使其具有栅极可调半导体输运,是实现其应用的关键.以此为目的,自20世纪末以来,多种金属量子结构便逐步被设计与开发,其输运特性的有效调控也被学术界广泛研究.本文回顾了零维量子点、一维纳米线/纳米管、二维材料/人工二维晶格/超导薄膜等不同维度金属量子结构的研究进展;针对这些结构体系,介绍了其各自的能隙调控思想,总结分析了可控输运特性的实现方法与内在机制,对比展示了材料结构的电学性能及应用前景.基于目前报道的研究结果,提出了未来预期的研究方向:开发金属量子结构中输运与自旋关联特性,设计同时传输电荷与自旋信息,且具有栅极可调输运带隙的全金属沟道材料、结构与器件.     

Carrier transport characteristics of H-terminated diamond films prepared using molecular hydrogen and atomic hydrogen

The H-terminated diamond films, which exhibit high surface conductivity, have been used in high-frequency and high-power electronic devices. In this paper, the surface conductive channel on specimens from the same diamond film was obtained by hydrogen plasma treatment and by heating under a hydrogen atmosphere, respectively, and the surface carrier transport characteristics of both samples were compared and evaluated. The results show that the carrier mobility and carrier density of the sample treated by hydrogen plasma are 15 cm2·V-1·s-1 and greater than 5×1012 cm-2, respectively, and that the carrier mobilities measured at five different areas are similar. Compared to the hydrogen-plasma-treated specimen, the thermally hydrogenated specimen exhibits a lower surface conductivity, a carrier density one order of magnitude lower, and a carrier mobility that varies from 2 to 33 cm2·V-1·s-1. The activated hydrogen atoms restructure the diamond surface, remove the scratches, and passivate the surface states via the etching effect during the hydrogen plasma treatment process, which maintains a higher carrier density and a more stable carrier mobility.     

CI/MC-CDMA与单载波系统的对比分析研究

将载波干涉技术与OFDM,MC-CDMA技术相结合的CI-OFDM,CI/MC-CDMA成为宽带无线通信领域新的研究热点之一。在前期研究的基础上，对CI/MC-CDMA的原理进行理论分析，证明了CI/MC-CDMA在原理上与CI-OFDM的相似性#理论分析CI/MC-CDMA系统等效于单载波系统，将载波干涉技术与MC-CDMA技术相结合无法提高MC-CDMA系统性能。     

Au/Ge/SiO2/p-Si结构中的电流输运特性

用射频磁控溅射双靶交替淀积的方法在p-Si(100)衬底上制备了Ge/SiO2薄膜,利用Au/Ge/SiO2/p-Si结构的I-V特性曲线研究了该结构的电流输运机制.分析表明,在较低的正向偏压和反向偏压下,电流输运机制分别为Schottky发射和欧姆输运电流;而在较高的正向偏压下,Frenkel-Poole发射和空间电荷限制电流两种机制共同作用.     

载体桩在白山的应用

介绍载体桩在白山棚户区改造中的应用,并与预制桩进行对比,通过收集到的技术设计及施工数据,发现了载体桩比预制桩具有桩长短而经济的优点,为白山的棚户区改造提供了一种经济有效的基础设计施工方法,并取得了显著的经济和社会效益。     

nc-Si:H薄膜的微结构特征与光学特性

利用射频等离子体增强型化学气相沉积(RF-PECVD)工艺,以SiH4和H2作为反应气体源,在玻璃和石英衬底上制备了氢化纳米晶硅(nc-Si:H)薄膜.采用Raman散射谱、原子力显微镜(AFM)、透射光谱方法对在不同衬底温度与不同H2稀释比条件下沉积生长薄膜的微结构和光学特性进行了实验研究.结果表明,nc-Si:H薄膜的晶粒尺寸为2.6～7.0nm和晶化率为45%～48%.在一定反应压强、衬底温度和射频功率下,随着H2稀释比的增加,薄膜的沉积速率降低,但晶化率和晶粒尺寸均有所增加,相应光学吸收系数增大.而在一定反应压强、射频功率和H2稀释比下,随着衬底温度的增加,沉积速率增加,薄膜晶化率提高.     

Photoconductive study and carrier dynamics of vertically aligned GaAs nanowires

Single wire devices are generally fabricated to study the electrical and photoelectric behaviors of semiconductor nanowires(NWs);however detriment or contamination can hardly be avoided during manipulation of NWs under focused ion and electron beams.This could not be a trivial factor for III-V NWs which are candidates for high efficiency solar energy harvesting and sensitive photodetection.In this study an alternative way to probe the photoconductive property of individual epitaxial GaAs NWs is presented.For the sample preparation,a uniform spin-coated layer of polymer was selected to be the supporting medium for the vertically aligned NWs structure;then the adequate thinning and polishing of the sample exposed the NW tip and also achieved the required height of NW.An external power adjustable laser was introduced as the excitation source,and the dark and photoconductive currentvoltage properties of individual NW were measured by the conductive atomic force microscopy.The typical Schottky style photoconductive behavior was observed in the vertically aligned GaAs NW,and its photoresponsivity has been found to be much higher than that of the reported for single NW photodetector.Finally,a numerical model based on the experimental setup was established to simulate the photoelectric behavior of individual NW.The minority hole lifetime has been found to dominate the photoconductive current-voltage properties of NW under the positive sample bias,and can be derived from the quantitative fitting of experimental photo-IV curves.     

氢化非晶碳膜导电机制的探索

采用电子回旋共振等离子体化学气相沉积 (ECR -CVD)方法 ,以苯为气源 ,在不同基片温度下制备了氢化非晶碳膜 (a -C :H) ,对样品进行了伏安特性测试。考察了基片温度对样品电阻率与击穿场强的影响 ,结合薄膜含氢量、SEM、Raman散射等分析手段探索了a -C :H膜的导电机制     

射频等离子体聚合多层复合薄膜的制备及性能

采用等离子体聚合方法,分别以甲基丙烯酸甲酯、正硅酸乙酯和甲基丙烯酸三氟乙酯为原料制备了3种聚合物薄膜,并利用扫描电镜(SEM)、原子力显微镜(AFM)、紫外可见光谱(UV-vis)和接触角(ContactAngle)等方法研究了不同条件下所得的聚合物薄膜的表面形貌、表面粗糙度、光学透明性及疏水性等性能.研究结果表明:聚甲基丙烯酸甲酯薄膜具有最好的可见光透过率和最佳的表面粗糙度(RMS).聚正硅酸乙酯薄膜的表面粗糙度随射频功率变化不大.聚甲基丙烯酸三氟乙酯薄膜在低功率下有较低的表面粗糙度,但随着入射功率的增加,等离子体刻蚀作用使得表面粗糙度增加.SEM照片表明聚甲基丙烯酸甲酯薄膜表面平坦致密无针孔.静态接触角测试结果表明三种聚合物薄膜都有较好的疏水性能,以聚甲基丙烯酸三氟乙酯薄膜的疏水性能最佳.利用等离子连续聚合的方法制备了聚甲基丙烯酸甲酯薄膜/聚正硅酸乙酯/聚甲基丙烯酸三氟乙酯3层复合薄膜,并对复合膜的性能进行了表征.     

FexPt100-x取向薄膜的结构与磁性

用电子束沉积法在加热到100℃的MgO（001）基板上生长了50nm厚的FexPt100-x取向薄膜,原子比成分范围为x=[10,85].在500℃进行保温2h的原位热处理后,分析样品的结构及沿面内和垂直于薄膜方向施加磁场的磁性行为.结果表明,随着x的增加,易磁化轴的方向在沿平行于膜面方向和垂直于膜面方向之间反复变化,取决于内秉的磁晶各向异性与外秉的形状各向异性之间的竞争.当x=60时,由于薄膜发生不完全的A1→L10相转变,形成了A1软磁相与L10硬磁相的复合体,样品沿平行和垂直于膜面方向磁化的矫顽力都达到5kOe（1Oe=79.5775Am-1）以上.沿膜面方向磁化时,矫顽力高于软磁相的磁晶各向异性场,并且正负向磁化的剩余磁化强度明显不相等.采用三磁畴软磁相模型,结合硬磁/软磁交换耦合作用,对此进行了解释.这种硬磁/软磁复合材料适合于用来制作磁力显微镜的各向同性高矫顽力探针.     

船舶运输效率的发展趋势

基于Nakazawa教授提供的有关20世纪70年代至2008年的液化气船、油船、集装箱船的船舶数据,利用K-G曲线对船舶特定输出功率(SOP)进行定量分析,浅析船舶运输效率的发展趋势和制约因素.     

信鸽竞翔系统的设计和实现

信鸽竞赛活动日见增多，信鸽比赛的管理开始采用自动管理系统．介绍了信鸽竞翔系统的基本设计思想，并给出了系统的软、硬件设计及实现框图。     

MWECR-CVD法高速沉积氢化非晶硅薄膜

介绍了一种新型的MWECR-CVD装置.该装置设计采用了一种由单个电磁线圈和永磁体单元组合的新型磁场,设计了一种新型的矩形耦合波导.应用这一装置使a-Si:H薄膜的沉积速率达到了2 nm/s以上.为了降低薄膜的光致衰退效应,提出了热丝辅助的MWECR-CVD,这一改进可以大大降低薄膜的氢含量,改善薄膜的光照稳定性.