中能重离子微束辐照装置的研制

微束辐照装置是将辐照样品的束斑缩小到微米量级, 能够对辐照粒子进行准确定位和精确计数的实验平台, 是开展辐照材料学、辐照生物学、辐照生物医学以及微加工的有力工具. 中国科学院近代物理研究所(IMP)正在研制中能重离子微束辐照装置. 该装置以兰州重离子加速器(HIRFL)系统提供的中能和低能重离子束流为基础, 采用磁聚焦方式形成微米束. 束运线上两台铅垂方向的偏转磁铁辅以四极磁铁构成对称消色差系统, 将束流导向地下室, 再用高梯度的三组合四极透镜强聚焦形成微米束斑, 在真空中或大气中辐照样品. 它将成为国内首台能够提供从低能(10MeV/u)到中能(100MeV/u)的重离子微束的公共实验平台, 用于定位、定量照射靶物质(生物细胞、组织或其它非生物材料等), 有助于深入揭示重离子与物质相互作用的本质, 也为探索重离子辐照效应的应用提供新的手段.     

射频磁控溅射ZnO薄膜的结构和光学特性

采用射频（RF）反应磁控溅射法在n-Si(001)衬底上外延生长ZnO薄膜。XRD谱测量显示出较强的（002）衍射峰，表明ZnO薄膜为c轴择优取向生长的。室温PL谱测量观察到了较强的紫外光发射和深能级发射。     

Comparative Study of Properties of ZnO／GaN／Al203 and ZnO／Al203 Films Grown by Low－Pressure Metal Organic Chemical Vapour Deposition

ZnO films were deposited by low-pressure metal organic chemical vapour deposition on epi-GaN/Al203 films and c-Al203 substrates. The structure and optical properties of the ZnO/GaN/Al203 and ZnO/Al203 films have been investigated to determine the differences between the two substrates. ZnO films on GaN/Al203 show very strong emission features associated with exciton transitions, just as ZnO films on Al2O3, while the crystalline structural qualities for ZnO films on GaN/Al2O3 are much better than those for ZnO films directly grown on Al203 substrates. Zn and O elements in the deposited ZnO/GaN/Al2O3 and ZnO/Al2O3 films are investigated and compared by x-ray photoelectron spectroscopy. According to the statistical results, the Zn/O ratio changes from Zn-rich for ZnO/Al2O3 films to O-rich for ZnO/GaN/Al2O3 films.     

MOCVD法生长SAWF用ZnO/Diamond/Si多层结构

使用等离子体辅助MOCVD系统在金刚石,硅衬底上成功地制备了氧化锌多层薄膜材料,通过两步生长法对薄膜质量进行了优化。XRD测试显示优化后的样品具有c轴的择优取向生长,PL谱测试表明样品经优化后不仅深能级发射峰消失,同时紫外发射峰增强。对优化后的样品的表面测试显示出较低的表面粗糙度。比较氧化锌多层薄膜结构的声表面波频散曲线,ZnO薄膜声表面滤波器受膜厚和衬底材料的影响较大。当ZnO薄膜较薄时,在它上面的传播速度将与衬底上的传播速度接近,与其他衬底上生长的薄膜相比,以金刚石这种快声速材料为衬底的ZnO多层薄膜结构,声表面波滤波器的中心频率将提高1倍左右。     

微束辐照装置及其在生物和材料领域中的应用

自从20世纪50年代开始利用微束辐照生物活细胞以来,由于微束独特的辐照特征, 其在生物学、 材料学、 生物医学、航空航天科学、环境科学、地质学、微加工等领域得到了广泛的应用。 在前人大量研究的基础上, 对微束装置及其应用进行总结概括。 展望了微束的发展趋势并简单介绍中国科学院近代物理研究所正在兴建的中高能重离子微束辐照装置。 Collimated proton microbeam has been used to irradiate the biological living cells since 1850s. Due to its unique characteristic in irradiation, microbeam has been extensively applied to many research fields,such as biology, material science, biomedicine,aeronautics and stronautics, environmental science, geology,micromachining and so on. Based on the much research of predecessors, the microbeam facilities and their corresponding applications are summarized in this paper. At last,prospects on the development trend of microbeam are made, and the intermediate energy and high energy heavy ion microbeam irradiation facility being constructed at the Institute of Modern Physics of Chinese Academy of Sciences is briefly introduced.     

Design of the IMP microbeam irradiation system for 100 MeV/u heavy ions

A state-of-the-art high energy heavy ion microbeam irradiation system is constructed at the Institute of Modern Physics of the Chinese Academy of Sciences. This microbeam system operates in both full current intensity mode and single ion mode. It delivers a predefined number of ions to pre-selected targets for research in biology and material science. The characteristic of this microbeam system is high energy and vertical irradiation. A quadrupole focusing system, in combination with a series of slits, has been designed to optimize the spatial resolution. A symmetrically achromatic system leads the beam downwards and serves simultaneously as an energy analyzer. A high gradient quadrupole triplet finally focuses a C^6＋ ion beam to 1 μm in the vacuum chamber within the energy range from 10 MeV/u to 100 MeV/u. In this paper, the IMP microbeam system is described in detail. A systematic investigation of the ion beam optics of this microbeam system is presented together with the associated aberrations. Comparison is made between the IMP microbeam system and the other existing systems to further discuss the performance of this microbeam. Then the optimized initial beam parameters are given for high resolution and high hitting efficiency. At last, the experiment platform is briefly introduced.     

ZnO薄膜的掺杂特性

通过MOCVD方法生长的ZnO薄膜一般为富锌生长,呈n型电导,要想得到高阻或低阻p-ZnO薄膜需要对其进行掺杂施主或受主杂质.主要研究在生长过程中通过NH₃对ZnO薄膜进行氮掺杂的情况,利用优化生长条件,即生长温度为610℃,Ar气(携带DEZn)流量为4sccm,O₂流量为120sccm,N₂流量为600sccm,得到在NH₃流量为80sccm时生长样品的结晶质量最高,在掺杂薄膜中NH₃流量高于或低于80sccm时,样品的表面形貌都将变差,只有在80sccm时表面粗糙度最低晶粒最小,表明该流量下获得的样品表面较光滑致密.所以80sccmNH₃流量为在R面蓝宝石上生长<110>取向ZnO薄膜的最佳掺杂流量.Hall测量结果表明,NH₃流量为50sccm的样品电导呈弱p型,电阻率为102Ω·cm,空穴载流子浓度为+1.69×10¹⁶cm^-3,迁移率为3.6cm²·V^-1·s^-1;当NH₃流量增加时样品的电导呈n型,电阻率最高达10⁸Ω·cm,我们认为与进入ZnO薄膜的H的量有关,并对其变化机理进行了详细的分析.     

等离子MOCVD系统生长ZnO薄膜掺N2和掺NH3特性比较

利用MOCVD方法生长了高质量的ZnO薄膜材料,分别通过N2和NH3对c面和R面蓝宝石衬底上生长的ZnO薄膜材料进行了掺杂行为研究.掺N2时,X射线衍射半峰全宽仅为0.148°,室温光荧光发光峰位于3.29eV,半峰全宽～100meV,电阻率由0.65 Ω·cm增大到5×l04Ω·cm.掺NH3时,X射线衍射峰半峰全宽0.50°,样品为弱p型,电阻率为102Ω·cm,载流子浓度为1.69×1016 cm-3.同时我们还观察到弱p型材料很容易退化成n型高阻材料.     

清洁、大流量真空差分系统的研制

本研究是为了设计一套大流量、清洁的真空差分系统. 计算了超重反冲核实验装置终端真空差分系统各级的真空度; 介绍了差分系统的设计和真空泵、测量设备选择; 选择能在高压强下连续运行的新型分子/增压泵作为过渡流范围内的主排气泵, 对分子增压泵进行了性能测试并对差分系统进行了模拟靶室实验, 最后对实验结果进行了分析.     

RFQ1L系统压升率的理论与实验研究

简单阐述了RFQ冷却聚束器对缓冲气体的要求, 从理论和实验两方面详细研究了RFQ1L系统的压升率。 研究表明, RFQ1L系统压升率的主要来源是真空室内材料表面的出气, 整个系统的压升率实测为（0.04±0.02） Pa/h。