SOI CMOS模拟集成电路发展概述

从SOI CMOS模拟集成电路(IC)中存在的关键问题--浮体效应--及其影响出发,介绍了在解决浮体效应以后,已实现的有代表性的模拟集成电路的发展状况.特别指出了SOICMOS在实现RF电路及SOC芯片中的优点.

射频CO_2激光陶瓷基板划片机光路设计及分析

介绍了RF CO_2激光陶瓷基板划片的特点.分析了导光系统的设计原则,着重讨论了圆偏振镜和伽利略离焦望远镜的作用和特点.对导光系统进行了优化和模拟,给出了导光系统的光路图及成像质量图.试验结果和理论相符,系统划片速度可达10 m/min,划缝宽度<0.1 mm,划缝深度>0.3 mm.利用所设计的陶瓷划片机加工的氧化铝陶瓷基片可与国外同类划片机相媲美.

Characteristics of AlGaN/GaN HEMTs Grown by Plasma-Assisted Molecular Beam Epitaxy

AlGaN/GaN high electron mobility transistor (HEMT) materials are grown by RF plasma-assisted molecular beam epitaxy (RF-MBE) and HEMT devices are fabricated and characterized. The HEMT materials have a mobility of 1035cm~2/(V ? s) at sheet electron concentration of 1.0 * 10~(13)cm~(-2) at room temperature. For the de-vices fabricated using the malt-rials,a maximum saturation drain-current density of 925mA/mm and a peak extrinsic iransecmductance of IHfimS/mm are obtained on devices with gate length and width of l/-im and 80/im respectively. The f_t, unit-current-gain frequency of the devices,is about 18. 8GHz.

用PECVD在低温衬底上制备类金刚石碳膜(英文)

报道用RF PECVD在低温衬底上制备了类金刚石碳(DLC)膜。研究了氢稀释、气体压力和RF功率对薄膜性质的影响。用光透射率、红外吸收谱和小角度X射线衍射谱分析了DLC膜的结构和光学性质。

Pt-Ni/p-InP低阻欧姆接触的机理研究

利用X射线衍射和AES(俄歇)方法，深入地研究了RF磁探溅射淀积的Pt-Ni/p-InP(100)非合金膜系在热退火过程中Pt和Ni与衬底InP中的In和P形成稳定化合物的行为，揭示了比接触电阻降低于3×10~(-6)Ω·cm~2的根本原因。

Low-frequency noise properties of GaN Schottky barriers deposited on intermediate temperature buffer layers

Metal-semiconductor-metal (MSM) structures were fabricated by RF-plasma-assisted MBE using different buffer layer structures. One type of buffer structure consists of an AlN high-temperature buffer layer (HTBL) and a GaN intermediate temperature buffer layer (ITBL), another buffer structure consists of just a single A IN HTBL. Systematic measurements in the flicker noise and deep level transient Fourier spectroscopy (DLTFS) measurements were used to characterize the defect properties in the films. Both the noise and DLTFS measurements indicate improved properties for devices fabricated with the use of ITBL and is attributed to the relaxation of residue strain in the epitaxial layer during growth process. (C) 2003 Elsevier Ltd. All rights reserved.

High-mobility Ga-polarity GaN achieved by NH3-MBE

GaN epilayers were grown on (0001) sapphire substrates by NH3-MBE and RF-MBE (radio frequency plasma). The polarities of the epilayers were investigated by in-situ RHEED, chemical solution etching and AFM surface examination. By using a RF-MBE grown GaN layer as template to deposit GaN epilayer by NH3-MBE method, we found that not only Ga-polarity GaN films were repeatedly obtained, but also the electron mobility of these Ga-polarity films was significantly improved with a best value of 290 cm(2)/V.s at room temperature. Experimental results show it is an easy and stable way for growth of high quality Ga-polarity GaN films.

Optimization of InGaAs quantum dots for optoelectronic applications

Quantum dot infrared photodetectors (QDIP) are in the center of research interest nowadays. However the real QDIP is inferior to those predicted in theory, in which the dot density is much higher than those reported. Through optimizing the growth conditions, we realized the control of high-density quantum dot growth. This will be very useful for future QDIP development.

Study on optical band gap of boron-doped nc-Si : H film

The optical band gap (E-g) of the boron (B)-doped hydrogenated nano-crystalline silicon (nc-Si:H) films fabricated using plasma enhanced chemical vapor deposition (PECVD) was investigated in this work. The transmittance of the films were measured by spectrophotometric and the E-g was evaluated utilizing three different relations for comparison, namely: alphahnu=C(hnu-E-g)(3), alphahnu=B-0(hnu-E-g)(2), alphahnu=C-0(hnu-E-g)(2). Result showed that E-g decreases with the increasing of Boron doping ratio, hydrogen concentration, and substrate's temperature (T-s), respectively. E-g raises up with rf power density (P-d) from 0.45W.cm(-2) to 0.60w.cm(-2) and then drops to the end. These can be explained for E-g decreases with disorder in the films.

稻田化感物质对土壤微生物和酶的作用及其迁移行为

本论文以化感水稻品种PI312777和非化感水稻品种辽粳9为试验材料，研究田间全生育时期内两种水稻根际土壤微生物及酶活性的变化；室内添加两种水稻苗期根系分泌物、水稻及稗草化感物质，探讨其对土壤微生物及酶活性的影响。测定指标有：土壤微生物生物量碳、微生物数量(细菌、放线菌、真菌、氨化细菌和好气性自生固氮菌)、土壤酶(脲酶、转化酶、脱氢酶和多酚氧化酶)活性和磷酸脂肪酸谱图分析。同时利用土壤薄层层析结合生物测定的方法研究化感物质在不同类型土壤中的迁移性能，结果表明： 1.种植水稻明显提高了土壤微生物生物量碳、微生物数量和酶活性。在生长的初始阶段(苗期到分蘖期)，化感水稻PI312777根际土壤微生物各项指标及酶活性均高于非化感水稻辽粳9。 2.两种水稻苗期根系分泌物均刺激土壤微生物并间接提高土壤酶活性，改变土壤微生物群落组成，处理间的效应因培养时间和水分条件而不同。 3.稗草化感物质——对羟基扁桃酸对水稻生长及土壤微生物的影响因浓度而呈现不同的效应。水稻化感物质对土壤微生物有不同的影响。苯甲酸和阿魏酸刺激土壤微生物及酶活性；黄酮对土壤微生物生物量碳和真菌数量有抑制作用。水分条件的变化导致微生物群落结构的改变，淹水条件下环丙基脂肪酸(cy17:0和cy19:0)及真菌脂肪酸含量减少。 4.不同化感物质在同一土壤中的迁移性能不同，而同一化感物质在不同土壤中的移动性也有差异；比移值Rf与土壤有机质含量、粘粒含量、阳离子交换量呈负相关，与土壤pH呈正相关。

文冠果壳苷提取工艺的研究

文冠果为我国独有的油料树种，研究发现，文冠果壳乙醇提取物具有良好的促智作用，文冠果壳苷（Xanthoceracide）为齐墩果烷型五环三萜皂苷，是文冠果壳乙醇提取物中活性最强的物质。大量的药效学实验证明其具有显著改善多种记忆障碍模型小鼠的学习能力，提高大脑的缺氧耐受能力，预防并治疗多发性栓塞引起的记忆保持障碍，降低谷氨酸造成的PC12细胞死亡数量，增强对神经细胞的保护作用；数例临床试验中，一些记忆力严重减退导致生活不能自理的老年人以及智力低下的儿童服用文冠果壳提取物或文冠果壳苷后，也有明显的康复效果或治疗效果；而急性毒性试验进一步证实，这些天然产物毒性低，仅仅1/50的LD50用量就能表现出明显的改善记忆障碍作用，这预示着文冠果壳乙醇提取物将有可能开发成有效的老年痴呆症特效药。 本研究采用薄层层析法（TLC）对文冠果壳提取物中的文冠果壳苷进行定性鉴别。显色剂为10%硫酸乙醇，操作方法简便，斑点清晰，Rf适中，重现性良好。采用分光光度法对文冠果壳总皂苷含量进行测定。用文冠果壳苷作为对照品，测定波长为546 nm，文冠果壳苷含量在0.004 mg·mL-1~0.02 mg·mL-1（r=0.9998）呈现良好的线性关系，方法检验合格。采用高效液相色谱法（HPLC）对文冠果壳苷进行含量测定，文冠果壳苷含量在0.02 mg·mL-1~0.2 mg·mL-1（r=0.9992）范围内线性关系良好，方法检验合格。 采用溶剂提取法，大孔吸附树脂分离，有机溶剂萃取，硅胶柱层析分离，结晶与重结晶等方法相结合，得到纯度达98.5%的文冠果壳苷，可作标准品为开发利用文冠果壳提供依据。 以出膏率和文冠果壳苷含量为考察指标，分别考察提取次数、提取温度、乙醇浓度、料液比以及提取时间等因素对提取效果的影响。采用正交试验优化文冠果壳苷的溶剂提取工艺，最终确定提取工艺为：用70%乙醇提取，料液比为1/7（W／V），提取时间为5 h，提取温度为60 ℃，提取次数为2次。采用中试放大试验验证该工艺条件，结果表明，该提取工艺简单，易操作，提取效果较好，具有较好的应用前景。