Inverted Solution Processable OLEDs Using a Metal Oxide as an Electron Injection Contact.

A new type of bottom‐emission electroluminescent device is described in which a metal oxide is used as the electron‐injecting contact. The preparation of such a device is simple. It consists of the deposition of a thin layer of a metal oxide on top of an indium tin oxide covered glass substrate, followed by the solution processing of the light‐emitting layer and subsequently the deposition of a high‐workfunction (air‐stable) metal anode. This architecture allows for a low‐cost electroluminescent device because no rigorous encapsulation is required. Electroluminescence with a high brightness reaching 5700 cd m^–2 is observed at voltages as low as 8 V, demonstrating the potential of this new approach to organic light‐emitting diode (OLED) devices. Unfortunately the device efficiency is rather low because of the high current density flowing through the device. We show that the device only operates after the insertion of an additional hole‐injection layer in between the light‐emitting polymer (LEP) and the metal anode. A simple model that explains the experimental results and provides avenues for further optimization of these devices is described. It is based on the idea that the barrier for electron injection is lowered by the formation of a space–charge field over the metal‐oxide–LEP interface due to the build up of holes in the LEP layer close to this interface.     

Sintering studies of nano-crystalline zinc oxide

Sintering and grain growth of nano-crystalline undoped ZnO has been studied in detail over a wide range of temperature and holding time. Below 800 °C, sintering of over 70% theoretical density is not observed, irrespective of particle size. At 900 °C for 6 h, the nano-crystalline sample sinters to 99% of theoretical density whereas the density for as received sample is 93% of theoretical density. However, at 1300 °C or higher, the densification is found to be much faster and after a few hours becomes independent of holding time. Grain growth studies reveal a similar feature of attaining saturation over holding time. The average saturated grain size is found to be ∼1.5 and ∼2.2 μm at 800 and 900 °C, respectively, while at 1300 °C or higher, it is in between 12 and 13 μm.     

Experimental Research on Erbium-doped Superfluorescent Fiber Source

The effects of the variations in fiber length, fiber mirror reflectance on efficiency and output power are experimentally investigated for erbium-doped double pass backward superfluorescent fiber sources (SFSs). The influence of fiber length on mean wavelength stability (MWS) has also been demonstrated. By incorporating a short section of un-pumped erbium-doped fiber (EDF) at the output port, the pump power dependent on MWS becomes independent of pumped EDF length. This is a novel phenomenon that hasn‘t been reported up to now,and should be helpful to SFS fabrication and theory analysis. By using a fiber Michelson interferometer as spectrum slicing component,a multi-wavelength fiber source (MWFS) with ～20 channels (from 1542nm to 1559nm) is got. The MWFS has a channel spacing of ～0. 8 nm which satisfies ITUstandard. The intensity fluctuation among channels is less than 0.5dB,and the extinction ratio of all channels is above 14dB. This kind of MWFS should be useful to wavelength division multiplexing systems.     

Growth of β-FeSi2 layers deposited from a molten salt

β-FeSi₂ layers have been successfully grown using a molten salt method for the first time. It was found that single phase and homogeneous β-FeSi₂ layers with a columnar domain structure can be grown on FeSi substrates. The layer thickness was demonstrated to be controllable by the growth temperature and time, and was diffusion controlled. It was shown that the layers were void- and crack-free compared to similar layers grown on Fe substrates: this difference is explained in terms of Fe diffusion. This vacuum-free simple growth technique is useful for the fabrication of large area semiconductor devices at low cost.     

Immunoelectron localization of mitochondrial F1 factor in cryosections of heart muscle cells

Immunocytochemistry was used to investigate the localization of F1 ATPase in mitochondria of cryosections of adult mouse heart muscle cells. The initial aldehyde fixation was the only denaturation step for antigens. The fine structure was preserved with contrast enhancement as the sections were maintained hydrated, with the advantage that the entire procedure is completed in one working day. The reaction was highly specific, and entire mitochondria were labeled with the Protein A-gold complex. A new analytical technique, electron spectroscopic imaging (ESI), contributed to a better visualization of the localization of the F1 factor.     

Fish assemblages and stream hydraulics: consistent relations across spatial scales and regions

General relationships between organisms and their habitat, consistent across spatial scales and regions, suggest the existence of repeatable ecological processes and are useful for the management of stream networks. From published data, we defined four guilds of European fish species with contrasting preferences for microhabitat hydraulics within stream reaches. At the scale of stream reaches and across 139 French sites (590 460 fishes sampled), we analysed how fish guild proportions were related to reach hydraulics (proportion of pools vs. riffles %POOL; median discharge by unit width Q50/W). The strongest correlations were observed between two fish guilds and %POOL (p < 0.001, r² ≥ 0.41) and between one fish guild proportion and Q50/W (p < 0.001, r² = 0.10). These reach–scale relationships were consistent across six large French basins, and consistent with the analyses made at the microhabitat scale. Therefore, microhabitat preferences for hydraulics are strong enough to generate consistent reach‐scale community responses to hydraulics across regions, despite the influence of other filters such as temperature, nutrient levels or history. The distribution of basic geomorphic features (pools, riffles) in streams and their modification (by dams, weirs and dikes) can modify the proportion of fish guilds by up to 80%, probably contributing to the long‐term decline of riffle‐dwelling species in Europe. Copyright © 2006 John Wiley & Sons, Ltd.     

异质谷间转移电子器件的计算机模拟

使用弛豫时间近似求出了描述两能谷间电子交换的方程。在此基础上建立了双能谷电子的连续性方程和油松方程。对具体的ＧａＡｓ／ＡｌｘＧａ１－ｘＡｓ异质谷间转移电子器件结构求解了这些方程组，得到了直流工作时器件内的电场分布、双能谷中载流子的布居以及两个能谷的电流分布。这些结果正好和常规Ｇｕｎｎ器件相反，说明了两种器件的不同工作机理。最后通过对低Ａｌ组份势垒结构的计算说明了Ｘ谷电子注入对器件工作的重要作用。     

电子束、离子束与蓝宝石相互作用的研究

研究了电子束、离子束作用于Al2O3表面时成分的变化，表明无论电子束或离子束都能使Al2O3发生分解，产生导电的元素Al。实验在PHI610·SAM上进行，电子束轰击下（3keV，O．5μA，入射角60°）10s就有元素Al分解出来，2min以后就达到饱和，分解析出量随时间成a（1－e－bt）的关系。离子束轰击下同样发生元素Al的分解，但当Ei＞3keV时，由于剥离速率加大，溅射5min时表面Al峰反而比1min时要弱。这时表面Al含量处于分解析出与溅射剥离的动态平衡中。实验还发现了Al2O3的解析与表面成分有关（如碳的含量）。最后讨论电子束与离子束的解析机理。     

片状陶瓷材料高低温电性能参数的自动检测

由进口电性能仪配上自制的高温系统，计算机自动采集数据，配置成一套高低温电性参数测定装置，该装置的特点是，升温快，炉体小巧，炉芯可更换盛液氮装置，屏蔽良好，等温区长，温工及参数测量精确可靠。     

显像（示）管阴极像黑洞状缺陷形成的原因及消除对策

本文通过有关理论依据和试验数据，着重阐述了在显像（示）管测试中，阴极像中心黑洞状缺陷产生的原因以及消除这种缺陷的处理方法。通过这种处理方法处理过的显像（示）管，其整体质量水平（尤其是真空度）将会得到明显的提高。