Deep levels,electrical and optical characteristics in SnTe-Doped GaSb Schottky Diodes

The GaSb layers investigated were grown directly on GaAs substrates by molecular beam epitaxy (MBE) using SnTe source as the n-type dopant. By using admittance spectroscopy, a dominant deep level with the activation energy of 0.23-0.26 eV was observed and its concentration was affected by the Sb₄/Ga flux ratio in the MBE growth. A lowest deep-level concentration together with a highest mobility was obtained for GaSb grown at 550°C under a Sb₄/Ga beam equivalent pressure (BEP) ratio around 7, which should correspond to the lowest ratio to maintain a Sb-stabilized surface reconstruction. In the Hall measurement, an analysis of the temperature-dependent mobility shows that the ionized impurity concentration increases proportionally with the sample’s donor concentration, suggesting that the ionized impurity was introduced by an SnTe source. In addition, optical properties of an undoped p-, a lightly and heavily SnTe-doped GaSb layers were studied by comparing their photoluminescence spectra at 4.5K.     

电源对介质阻挡放电(DBD)激发准分子(XeCl*)辐射的影响

本文对电源参数如电压幅值、频率及正负电压对介质阻挡放电激发准分子XeCl 紫外 (30 8nm)辐射的影响进行了实验研究。结果表明 ,UV辐射随电压幅度的增加而增强 ,但效率下降 ;提高频率 ,增加了放电次数 ,导致UV辐射的增强 ;此外 ,在较高的频率下 ,电压上升沿变陡 ,使得电子获得的能量主要用于原子的激发和电离。正、负电压放电的不对称源于电极结构的不对称而引起的放电过程的差异 ,负电压内电极可向放电管中馈入更多的能量 ;比较发光光谱可判断生成准分子的等离子体化学过程没有明显的差别     

Barrier layer effect of tantalum on the electromigration in sputtered copper films on hydrogen silsesguioxane and SiO2

As IC devices scale down to the submicron level, the resistance-capacitance (RC) time delays are the limitation to circuit speed. A solution is to use low dielectric constant materials and low resistivity materials. In this work, the influence of underlying barrier Ta on the electromigration (EM) of Cu on hydrogen silsesquioxane (HSQ) and SiO₂ substrates was investigated. The presence of a Ta barrier not only improves the adhesion between Cu and dielectrics, but also enhances the crystallinity of Cu film and improves the Cu electromigration resistance. The activation energy obtained suggests a grain boundary migration mechanism and the current exponent calculated indicates the Joule heating effect.     

钛合金的银脆,镉脆敏感性及其控制

利用慢应变速率拉伸技术（ＳＳＲＴ），并结合恒载实验，较全面地研究了Ｔｉ－６Ａｌ－４Ｖ合金的银脆行为、固态与液态镉脆行为，确定了应变速率、接触条件、热处理制度、试样取向、温度等因素对Ｔｉ－６Ａｌ－４Ｖ合金银脆与镉脆敏感性的影响，探讨了Ｎｉ阻挡层对控制Ｔｉ－６Ａｌ－４Ｖ合金和ＴＣ１１合金银脆开裂的作用。     

CO_2激光对兔脑组织血脑屏障的影响

同等功率和照射时间条件下,在14只家兔大脑皮质运用伊文思蓝染料和超微结构观察方法进行血脑屏障改变的研究。结果表明:CO_2激光作用十分表浅,且激光作用后的水肿层血脑屏障改变是可逆的。     

动情期家兔输卵管上皮及其分泌活动的电镜观察

本实验用透射电镜和扫描电镜观察了动情期家兔输卵管上皮。证实分泌细胞和纤毛细胞都有分泌功能，共分泌三种分泌物质。本文对这些分泌物质的分泌方式、分泌活动进行了研究和探讨。另外，发现上皮基膜下方始终有一层成纤维细胞形成的胞质膜伴行，据此，对血一输卵管腔屏障的构成亦进行了讨论。     

Formation of low-resistivity poly-Si and SiNx films by Cat-CVD for ULSI application

In this paper, bulk-Si metal–oxide–semiconductor field effect transistors (MOSFETs) are fabricated using the catalytic chemical vapor deposition (Cat-CVD) method as an alternative technology to the conventional high-temperature thermal chemical vapor deposition. Particularly, formation of low-resistivity phosphorus (P)-doped poly-Si films is attempted by using Cat-CVD-deposited amorphous silicon (a-Si) films and successive rapid thermal annealing (RTA) of them. Even after RTA processes, neither peeling nor bubbling are observed, since hydrogen contents in Cat-CVD a-Si films can be as low as 1.1%. Both the crystallization and low resistivity of 0.004 Ω·cm are realized by RTA at 1000 °C for only 5 s. It is also revealed that Cat-CVD SiN_x films prepared at 250 °C show excellent oxidation resistance, when the thickness of films is larger than approximately 10 nm for wet O₂ oxidation at 1100 °C. It is found that the thickness required to stop oxygen penetration is equivalent to that for thermal CVD SiN_x prepared at 750 °C. Finally, complementary MOSFETs (CMOSs) of single-crystalline Si were fabricated by using Cat-CVD poly-Si for gate electrodes and SiN_x films for masks of local oxidation of silicon (LOCOS). At 3.3 V operation, less than 1.0 pA μm⁻¹ of OFF leakage current and ON/OFF ratio of 10⁷–10⁸ are realized, i.e. the devices can operate similarly to conventional thermal CVD process.     

High‐pressure processing effects on the mechanical,barrier and mass transfer properties of food packaging flexible structures: a critical review

Food products can be high‐pressure processed (HPP) either in bulk or prepackaged in flexible or semi‐rigid packaging materials. In the latter case the packaging material is subjected, together with the food, to high‐pressure treatment. A number of studies have been performed to quantify the effects of high‐pressure processing on the physical and barrier properties of the packaging material, since the integrity of the package during and after processing is of paramount importance to the safety and quality of the food product. This article reviews the results of published research concerning the effect of HPP on packaging materials. Copyright © 2004 John Wiley & Sons, Ltd.     

Electrical conductivity in iodine-doped ethyl cellulose

The electrical conductivity of solution-grown ethyl cellulose (EC) films, 5–30 μm thick, has been studied in the sandwich configuration (metal–EC–metal) as a function of iodine concentration from 0.5 to 5.0 wt% ratio. The studies were conducted in the temperature range 333–383 K, while the field was varied over the range (3.0–5.5) × 10⁴V/cm. Aluminium was used as the lower electrode, while the upper electrode was of Al, Ag, Cu, Au or Sn. Certain transient effects such as a large burst of current immediately after the application of field were observed. An attempt was made to identify the nature of the current by comparing the observed dependence on electric field, electrode material and temperature with the respective characteristic features of the existing theories of electrical conduction. The results show that the electrical conduction follows Ohm's law at lower fields, while at higher fields, space-charge limited current (SCLC) was observed. It was also found that Richardson–Schottky emission was responsible, to some extent, for the transport of charge carriers in the polymer. The conductivity of the films increased on doping with iodine. The dopant molecules are considered to act as additional trapping centes and provide links between the polymer molecules in the amorphous region, thus resulting in the formation of charge transfer complexes.