Characteristics and Gas Sensing Properties of ZnO Thin Films Doped by Dy~(3+) and La~(3+)

采用真空蒸发的方法制备了掺杂原子比为3%、5%和9%的lA掺杂和dy掺杂的znO薄膜.用扫描电子显微镜(SEM)、X射线衍射(Xrd)谱和X射线光电子能谱(XPS)表征了所制得的znO薄膜的特性.发现所有薄膜都沿C轴取向优先生长.在对znO薄膜气敏特性的测量中,在低温条件下掺杂znO薄膜的电阻比非掺杂znO薄膜的小,且对乙醇和丙酮的灵敏度显著增强,且其中dy掺杂的znO薄膜的气敏特性较lA掺杂的znO薄膜为高.而空气中暴露9个月后的薄膜的气敏特性表明掺杂znO薄膜具有很好的稳定性.同时讨论了气敏传感机制和掺杂行为对薄膜灵敏度的影响.La and Dy-doped ZnO thin films were prepared via vacuum evaporation method at mass fraction of 3%,5% and 9% dopi ng.The obtained films were characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS).The results indicated that all films showed a preferred C-axis growth orientation.Compared with undoped ZnO thin films,the doped films exhibited a downshift of resistance at a low temperature and remarkable increase of sensitivity to ethanol and acetone vapour,and the sensitivity of Dy-doped ZnO thin films were higher than the sensitivity of La-doped ZnO thin films.The films were then exposed bare in air for 9 months and the sensitivity was remeasured.All the films remained the sensitivity at a high level which indicated an excellent stability.The sensing mechanism and the effect of doping behaviour were also discussed.国家重点基础研究发展计划(973)项目(2011CB301905;2012CB619301); 国家自然科学基金项目(61108064;61227009); 中央高校基本科研业务费专项(2010121056

Ab initio study of the substitutional point defect of silicon in aluminum

【中文摘要】 Point defects are the most simple defects in a solid.Nevertheless,a great number ofphysical and mechanical properties are sensitive to their presence.Furthermore,defectssuch as line imperfections,planar imperfections and cavities which are crucial to materialbehaviour are all influenced by their interactions with point defects.Therefore detailedknowledge of point defect is of great importance for understanding the atomistic as well asthe macroscopic behaviour of a material.Because of the importance of a...supported by the National Natural Science Foundation of China

金属铝中Si点缺陷的第一原理研究

【中文摘要】 点缺陷是固体中最简单的一种缺陷,然而固体的许多物理和机械性质都敏感于点缺陷的存在。另外,固体中的其他各种对材料性质起决定作用的缺陷,如线缺陷、面缺陷和空洞等都受到与点缺陷的相互作用的影响。因此,详细地研究点缺陷的性质对理解材料的微观和宏观性质都有重要作用。由于金属铝及其合金在航空航天和电子工业上的重要性,对铝及其合金的研究受到了很大的重视。硅是铝中最重要的杂质缺陷之一。铝-硅合金也是最重要的商业化合金之一(当加入0.01％(重量分数)Na时)。这种合金的微结构和机械性质在少量外来原子加入后得到了很大的改善。国家自然科学基金;国家教委留学回国人员资助项

α粒子轰击钍和铀引起的M亚壳层电离

本文研究2.5—4.5MeVα粒子轰击Th和U引起的M亚壳层电离。采用最小二乘法拟合实验谱求得N_(6,7)→M_5(M_α线),N_6→M_4(M_β线),N_5→M_3(M_γ线),N_4→M_2和N_2→M_1线的x射线产生截面。利用M壳层的辐射跃迁率,Coster—Kronig跃迁率和M亚壳层的荧光产额将x射线产生截面转换为M亚壳层电离截面。将实验所得的M亚壳层电离截面与PWBA和ECPSSR理论预言值进行比较,本文讨论了理论值与实验结果之间的偏差来源

氧离子与氖原子碰撞转移电离过程研究

采用位置灵敏探测和散射离子 反冲离子飞行时间测量技术,测量了氧离子与氖原子碰撞过程中转移电离截面与单电子俘获截面之比。通过比较,发现测量结果与文献结果的趋势一致,并对测量结果进行了解释

氧离子与氦、氖原子碰撞中转移电离过程的研究

采用位置灵敏探测和散射离子 反冲离子飞行时间测量技术,测量了氧离子与氖和氦原子碰撞过程中转移电离截面与单电子俘获截面之比。通过比较发现测量结果与文献结果的趋势一致,并对测量结果进行了讨论

JUNO Sensitivity on Proton Decay p→νˉK+p\to \bar\nu K^+ Searches

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this paper, the potential on searching for proton decay in $p\to \bar\nu K^+$ mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits to suppress the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar\nu K^+$ is 36.9% with a background level of 0.2 events after 10 years of data taking. The estimated sensitivity based on 200 kton-years exposure is $9.6 \times 10^{33}$ years, competitive with the current best limits on the proton lifetime in this channel