Impact of preanneal process on threshold voltage of MOS transistors for trench DRAM

As the first step of DRAM manufacture, preanneal process plays an important role in determining the threshold voltage variation. It is found that the higher trans-1,2-dichloroethene flow in pad oxide growth and the higher nitrogen flow in high-temperature annealing step would respectively engender a lower boron segregation coefficient and higher nitridation of the oxide, both modify the boron distribution in the substrate and consequently the behavior of the threshold voltage. As the feature size of DRAM devices enter nanometer regime, besides gate oxidation, ion implantation and related thermal processes, the impact of preanneal process condition should be prudentially taken into consideration for rigorous control of the threshold voltage in the advanced DRAM production.     

A study of diffusion in poly(ethyleneglycol)-gelatin based semi-interpenetrating networks for use in wound healing

Semi-interpenetrating networks (sIPNs) designed to mimic extracellular matrix via covalent crosslinking of poly(ethylene glycol) diacrylate in the presence of gelatin have been shown to aid in wound healing, particularly when loaded with soluble factors. Ideal systems for tissue repair permit an effective release of therapeutic agents and flow of nutrients to proliferating cells. Appropriate network characterization can, consequently, be used to convey an understanding of the mass transfer kinetics necessary for materials to aid in the wound healing process. Solute transport from and through sIPNs has not yet been thoroughly evaluated. In the current study, the diffusivity of growth factors and nutrients through the polymeric system was determined. Transport of keratinocyte growth factor was modeled by treating the sIPN as a plane sheet into which the protein was loaded. The diffusion coefficient was determined to be 4.86 × 10⁻⁹ ± 1.86 × 10⁻¹² cm²/s. Glucose transport was modeled as flow through a semi-permeable membrane. Using lag-time analysis, the diffusion coefficient was calculated to be 2.25 × 10⁻⁶ ± 1.98 × 10⁻⁷ cm²/s. The results were evaluated in conjunction with previous studies on controlled drug release from sIPNs. As expected from Einstein-Stokes equation, diffusivity decreased as molecular size increased. The results offer insight into the structure-function design paradigm and show that release from the polymeric system is diffusion controlled, rather than dissolution controlled.     

A thin multi-ring negative liquid crystal lens enabled by high-�� dielectric material

This study is dedicated to design an liquid crystal (LC) negative lens with unequal width electrodes, which is made for a camera lens and with the aim to replace conventional negative lenses. The structure of the LC negative lens is symmetric for producing a symmetrical electric field. The unequal widths are adopted and determined inversely proportional to the slopes of the desired applied voltages at varied radial positions. There are four ring electrodes in the lens and the associated with applied different voltages. In addition, the performance of the designed LC lens is verified by the software DIMOS.2D. The special structure and the material are used to realize the designed LC lens. Moreover, a new fabrication process in the wafer level to bury bus lines is developed in order to smooth the generated electric field distribution. In addition, a high-?? dielectric layer is coated between the electrodes and the LC layer for minimizing required applied voltage. Finally, differential effects of the LC lens structure with high-?? and without high-?? are discussed based on simulation results.     

Phase-shifting algorithms for electronic speckle pattern interferometry

A set of innovative phase-shifting algorithms developed to facilitate metrology based on electronic speckle pattern interferometry (ESPI) are presented. The theory of a phase-shifting algorithm, called a (5,1) algorithm, that takes five phase-shifted intensity maps before a specimen is deformed and one intensity map after a specimen is deformed is presented first. Because a high-speed camera can be used to record the dynamic image of the specimen, this newly developed algorithm has the potential to retain the phase-shifting capability for ESPI in dynamic measurements. Also shown is an algorithm called a (1,5) algorithm that takes five phase-shifted intensity maps after the specimen is deformed. In addition, a direct-correlation algorithm was integrated with these newly developed (5,1) or (1,5) algorithms to form DC-(5,1) and DC-(1,5) algorithms, which are shown to improve significantly the quality of the phase maps. The theoretical and experimental aspects of these two newly developed techniques, which can extend ESPI to areas such as high-speed dynamic measurements, are examined in detail.     

Terahertz Microchip for Illicit Drug Detection

To accurately detect minute amounts of substances without disturbing the surroundings of target molecules has been a major goal in bioanalytical technology. Here by integrating an optoelectronic terahertz (THz) microsource into a glass-substrated microchip within the near-field distance, we demonstrate a compact, label-free, noninvasive, and sensitive microbiosensing system with low-power consumption. The demonstrated THz microchip allows us to locally specify various illicit drug powders with weights of nanograms, with a promising future for rapid identification of the static status or even the dynamics of various biomolecules     

钢筋混凝土人工气候加速腐蚀的试验研究

在分析了含有氯离子的混凝土内钢筋锈蚀机理的基础上，介绍了利用人工气候实验室进行混凝土内钢筋加速锈蚀的试验，并对试验结果进行了分析。试验表明，温度和相对湿度对受氯离子侵蚀的混凝土内钢筋的锈蚀速度有很大影响，随着温度或相对湿度的提高，钢筋的锈蚀速度也会加快。试验还表明钢筋的保护层厚度及直径大小也明显影响它的锈蚀速度。     

地空导弹系统可测试性设计

针对地空导弹武器系统检测维修困难的现状，利用可测性设计技术，提出了地空导弹武器系统可测性设计的方法。阐述了地空导弹武器中测试性设计的必要性，论述了可测性设计的基本理论，分析了地空导弹武器系统可测性设计涉及的相关问题。     

Characterization of Si implants in p-type GaN

Si ion implantation into p-type GaN followed by rapid thermal annealing (RTA) in N/sub 2/ has been performed. X-ray diffraction analyses indicate that ion-implanted damage remains even with 1050/spl deg/C, 60 s RTA. By varying implantation and postimplantation annealing conditions, we could convert carrier concentration from p-type 3 /spl times/ 10/sup 17/ cm/sup -3/ into n-type 2 /spl times/ 10/sup 17/ cm/sup -3/ /spl sim/2 /spl times/ 10/sup 19/ cm/sup -3/. It was found that typical activation energies of Si implants in p-GaN are lower than 10 meV. Such activation energies are smaller than those observed from epitaxially grown Si-doped GaN films. A deep donor level with activation energy of 60 meV was also found from some samples. Photoluminescence studies show that the peak appears at 372 nm might be related to implantation-induced defects. It was also found that a green emission band could be observed from Si-implanted GaN. It was shown that such a green emission is related to the yellow band observed from epitaxially grown Si-doped GaN. The transport properties of these Si-implanted samples were also studied.     

某框架—剪力墙结构的鉴定与加固设计

通过对某停建多年建筑物的安全性鉴定，发现已建楼层的部分梁、柱、剪力墙等构件存在结构安全问题，并对该部分构件分别采用几种可行的加固措施进行处理,同时，还对续建楼层的钢筋连接提出了解决的方法。