InAlAs/InGaAs Pseudomorphic High Eelectron Mobility Transistors Grown by Molecular Beam Epitaxy on the InP Substrate

A novel PMMA/PMGI/ZEP520 trilayer resist electron beam lithograph （EBL） technology is successfully developed and used to fabricate the 150 nm gate-length In0.7Ga0.3As/In0.52Al0.48As Pseudomorphic HEMT on an InP substrate, of which the material structure is successfully designed and optimized. A perfect profile of T？gate is successfully obtained. These fabricated devices demonstrate excellent dc and rf characteristics： the transconductance Gm, maximum saturation drain？to-source current IDSS, threshold voltage VT, maximum current gain frequency fT derived from h21, maximum frequency of oscillation derived from maximum available power gain/maximum stable gain and from unilateral power？gain of metamorphic InGaAs/InAlAs high electron mobility transistors （HEMTs） are 470 mS/mm, 560 mA/mm, -1.0 V, 76 GHz, 135 GHz and 436 GHz, respectively. The excellent high frequency performances promise the possibility of metamorphic HEMTs for millimeter-wave applications.     

不同产地两面针根药材中微量元素的含量测定

应用电感耦合等离子体-原子发射光谱法(ICP-AES)和原子荧光光谱法(AFS)对广西12个不同产地两面针根的19种微量元素进行分析测定,该方法通过硝酸-高氯酸消解体系,有效彻底地消解样品中的有机物;而对于易挥发元素汞、硒,则通过控制样品的消解量、消解温度和消解时间,从而达到最佳的消解效果。该方法简单、高效、试剂用量少、结果准确,加标回收率为90.12%—104.14%,精密度均小于3%。结果表明,不同产地中药两面针根的微量元素含量有异,Na、Mg、K、Ca、Zn、Mn几种人体必需微量元素在不同产地两面针根的含量丰富,重金属元素Cr、As未检出,12个产地的Hg和11个产地的Pb均符合药用和出口标准,但Cd含量均超过药用和出口标准。此结果为研究两面针药材微量元素和药效相关性提供有效的数据,为两面针规范化种植基地选择及临床安全用药提供科学实验依据。     

离子液体中的聚合反应研究进展

室温离子液体是一种新兴的可替代挥发性有机化合物（VOCs）的绿色溶剂和高效的反应介质，为减少或消除化学反应和过程工程中的环境问题提供了重要的途径。以离子液体为反应介质进行聚合反应，可消除或减小VOCs的危害，也可实现催化剂的有效回收利用和聚合物的纯化，更好地控制聚合反应及聚合产物的结构与性质、乃至直接用作高效的聚合催化剂。本文综述近年来离子液体中聚合反应的研究现状及最新进展，分析现存的问题，并展望今后的发展方向。     

用1.05,0.53μm激光辐照Au盘靶的吸收规律与数值模拟

离散等离子体卡计测量等离子体能量,研究～0.8ns,1.05,0.53μm激光辐照Au盘靶产生的Au等离子体对激光的吸收规律.报道了吸收与激光入射角度和功率密度关系的实验结果.根据分析实验结果提出了吸收的定标规律.实验结果与一维平面等离子体模型模拟结果相符. 关键词：     

FIB快速加工纳米孔点阵的新方法

纳米尺度的点阵在纳米器件和基础科学研究方面都具有非常重要的应用.目前普遍采用的聚焦离子束和电子束曝光技术可以很方便的在衬底上加工纳米量级的微细结构，但大面积的图形加工过程需要花费太多的机时.介绍一种利用设计图形BMP文件的像素点阵和实际加工区域之间的匹配关系，通过聚焦离子束加工获得所需要的纳米孔点阵的新方法.采用这种方法可以在短时间内获得大面积的纳米点阵结构. 关键词： 聚焦离子束 电子束曝光 纳米孔点阵     

Fabrication and Characterization of YBa2Cu3Oy Superconducting Nanowires

Ordered YBa2Cu3Oy nanowires have been fabricated by filling YBa2Cu3Oy melting liquid into the pores of the anodized alumina templates. X-ray powder diffraction proves that YBa2Cu3Oy nanowires crystallized in the Y-123 structure. The temperature dependence of ac susceptibility indicates a superconducting transition at 91 K for the YBa2Cu3Oy nanowire array.     

激光打靶发射的(3/2)ω_0和2ω_0谐波的能量测量

本文介绍了采用“神光”装置基频钕玻璃激光(λ=1.053μm)打平面靶和黑洞靶所发射的3/2ω_0和2ω_0谐波的能量测量原理和方法,给出了相应实验结果,并对所得结果进行了简要的分析和讨论。     

新型同双核钛茂金属催化MMA本体聚合

合成了两个新的同双核钛茂金属催化剂：[（C5H5）TiC12]2[C3H4CH2CH2OCH2CH2C5H4]（A）和[（C5H5）TiCl2]。[C5H4CH4C5H4C6H4CH2C5H4]（B）,以元素分析和1H—NMR对配合物进行了表征．在Al（i-Bu）3的助催化下,A,B两个催化剂均可有效催化MMA本体聚合．详细考察了聚合时间、温度、nAl／nCat和nMMA／nCat对反应的影响．这两个催化体系的聚合转化率均可以达到85％左右．A／Al（i-Bu）3催化体系在聚合条件nMMA／nCat=2000,nAl／nCat=20,T=60℃。t=15h下,所得PMMA的Mn可以达到34×10^4,相对分子质量分布1．68,间同质量分数68％;B／Al（i-Bu）3催化体系在聚合条件nMMA／nCat=1500,nAl／nCat=10,T=60℃,t=15h下。所得PMMA的眠可以达到8×10^4,相对分子质量分布8．04,间同质量分数76％．     

Characterization of ZnO nanowire field-effect transistors and exposed to ultraviolet radiation

A ZnO nanowire (NW) field-effect transistor (FET) is fabricated and characterized, and its characterization of ultraviolet radiation is also investigated. On the one hand, when the radiation time is 5~min, the radiation intensity increases to 5.1~μ W/cm², while the saturation drain current (I_\rm dss) of the nanowire FET decreases sharply from 560 to 320~nA. The field effect mobility (μ ) of the ZnO nanowire FET drops from 50.17 to 23.82~cm²/(V.s) at V_\rm DS=2.5~V, and the channel resistivity of the FET increases by a factor of 2. On the other hand, when the radiation intensity is 2.5~μ W/cm^2 , the DC performance of the FET does not change significantly with irradiation time (its performances at irradiation times of 5 and 20~min are almost the same); in particular, the I_\rm dss of NW FET only reduces by about 50~nA. Research is underway to reveal the intrinsic properties of suspended ZnO nanowires and to explore their device applications.     

A k-band broadband monolithic distributed frequency multiplier based on nonlinear transmission line

A fabrication technology of GaAs planar Schottky varactor diode (PSVD) is successfully developed and used to design and manufacture GaAs-based monolithic frequency multiplication based on 23-section nonlinear transmission lines (NLTLs) consisting of a coplanar waveguide transmission line and periodically distributed PSVDs. The throughout design and optimization procedure of 23-section monolithic NLTLs for frequency multiplication in the k-band range is based on a large signal equivalent model of PSVD extracted from small-signal S-parameter measurements. This paper reports that the distributed SPVD exhibits a capacitance ratio of 5.4, a normalized capacitance of 0.86 fF/μm2 and a breakdown voltage in excess of 22 V. The integrated 23-section NLTLs fed by 20-dBm input power demonstrates a 26-GHz peak second harmonic output power of 14-dBm with 25.3% conversion efficiency in the second harmonic output frequency range of 6 GHz-26 GHz.