AlGaN/AlN/GaN/InGaN/GaN DH-HEMTs with improved mobility grown by MOCVD

AlGaN/AlN/GaN/InGaN/GaN double heterojunction high electron mobility transistors (DH-HEMTs) structures with improved buffer isolation have been investigated. The structures were grown by MOCVD on sapphire substrate. AFM result of this structure shows a good surface morphology with the root-mean-square roughness (RMS) of 0.196 nm for a scan area of 5 mu mx5 mu m. A mobility as high as 1950 cm(2)/Vs with the sheet carrier density of 9.89x10(12) cm(-2) was obtained, which was about 50% higher than other results of similar structures which have been reported. Average sheet resistance of 327 Omega/sq was achieved. The HEMTs device using the materials was fabricated, and a maximum drain current density of 718.5 mA/mm, an extrinsic transconductance of 248 mS/mm, a current gain cutoff frequency of 16 GHz and a maximum frequency of oscillation 35 GHz were achieved.

重力和重力梯度数据三维相关成像

本文提出了重力异常三维相关成像方法和重力梯度数据三维相关成像方法，并提出了基于异常分离的三维相关

EFFECT OF TOTAL HYDROGEN CONTENT IN SILICON-NITRIDE SENSITIVE FILM ON PERFORMANCE OF ISFET

Quantitative determinations of the hydrogen content and its profile in silicon nitride sensitive films by the method of resonant nuclear reaction have been carried out. At a deposition temperature of 825-degrees-C, hydrogen exists in an LPCVD silicon nitride sensitive film and the hydrogen content on its surface is in the range (8-16) x 10(21) cm-3, depending on the different deposition processes used. This hydrogen content is larger than the (2-3) x 10(21) cm-3 in its interior part, which is homogeneous. Meanwhile, we observe separate peaks for the chemical bonding configurations of Si-H and N-H bonds, indicated by the infrared absorption bands Si-O (1106 cm-1), N-H (1200 cm-1), Si-H-3 (2258 cm-1) and N-H-2 (3349 cm-1), respectively. The worse linear range of the ISFET is caused by the presence of oxygen on the surface of the silicon nitride sensitive film. The existence of chemical bonding configurations of Si-H, N-H and N-Si on its surfaces is favourable for its pH response.

共源-共栅组态S~2I电流存储单元及其性能

针对原型S~2I开关电流存储单元性能上的一些弱点，提出了共源-共栅组态的S~2I电流存储单元（简称CS~2I）新结构，使其关键速度与精度性能得到较好的改善。相同器件尺寸下的CS~2I单元电路相比，后者速度性能提高了1.6倍，两种电路结构同样应用于延迟单元和双采样双线性积分器功能部件的HSPICE仿真表明

阵列CsI(Tl)探测器鉴别轻带电粒子

文中描述了一个5×5阵列CsI(Tl)探测器结构以及对轻带电粒子的鉴别,CSI晶体有快慢两种成分。通过不同延迟和积分门的选择得到这两种信号,来进行轻带电粒子的鉴别。经过理论模拟和实验测试,发现不同的延迟和门的宽度对鉴别能力都有影响。

HIRFL-CSR实验环电子冷却装置磁场测量

在HIRFL-CSR实验环电子冷却装置上采用了独立的高精度螺线管串联产生纵向磁场的设计,获得很高的冷却段磁场平行度。使用霍尔片测量磁场的分布,使用磁针测磁方法测量冷却段磁场的磁轴偏角,并根据测量及计算结果对单个线圈磁轴进行微调。测量及调试结果表明,在施加电流为额定电流的一半时,冷却段磁感应强度为0.078T,剩余磁场小于2×10-4T,磁场不平行度小于1×10-4,达到了预期的设计目标。

The evolution of chemical components of aerosols at five monitoring sites of China during dust storms

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HIRFL辐照终端照射野均匀度与离子通量的关系

采用固体核径迹探测器聚碳酸脂膜,测定了兰州重离子研究装置提供的55MeV/u40Ar和80MeV/u20Ne离子束经辐照终端束流均匀化扫描装置后照射野均匀度与离子通量之间的关系.结果表明:对于40Ar和20Ne离子束,离子通量小于1×106和2×107ions/cm2时,横向照射野均匀度缓Ne离子束照射慢增加;当离子通量分别介于1×106—1×107和2×107—1×108ions/cm2时,40Ar和20野均匀度逐渐增加;离子通量达到1×107和1×108ions/cm2时,40Ar和20Ne离子束照射野均匀度分别约为58%和61%.从而说明,辐照终端束流扫描装置对束流的均匀化程度目前并不能满足辐照生物效应、辐射育种和重离子治癌等研究工作的需要,须对其性能做进一步的提高.

稀土区质子滴线核~(142)Ho的β缓发质子衰变

通过重离子引起的核反应106Cd(40Ca,p3n)合成了新的β缓发质子先驱核142Ho,并且配合氦喷嘴快速带传输系统用“p-γ”符合方法对它进行了首次鉴别.观测了142Ho的β缓发质子衰变,测定其半衰期为(0.4±0.1)s.利用统计模型拟合实验估计的对质子女儿核141Tb中末态的相对分支比和缓发质子能谱,142Ho的基态自旋被指认为5,6或7.用Woods-Xason Strutinsky方法计算了142Ho的核位能面,其结果支持指认142Ho的基态自旋宇称为7-.作为副产品,还首次观测到了来自先驱核139Gd,140Tb,142Tb和143Dy的β缓发质子衰变产生的质子女儿核中的一些γ跃迁.

毛细管式的靶-离子源系统在线实验研究

讨论了在线同位素分离器使用激光离子源的必要性 ,分析研究了毛细管式激光离子源对电离器的要求及热毛细管电离器的工作原理 ,并给出了在线实验的结果 .为了在较低温度下形成等离子体鞘势和降低热电离效率 ,采用了低电子逸出功的耐高温材料Nb作毛细管材料 .在线实验获得成功 ,使用毛细管式的靶 -离子源的在线同位素分离器的总效率约达 0 2 % ,满足了激光离子源电离器和靶室的工作要求