• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >The effects of residual gases on the field emission properties of ZnO, GaN, ZnS nanostructures, and the effects of light on the resistivity of graphene.
【24h】

The effects of residual gases on the field emission properties of ZnO, GaN, ZnS nanostructures, and the effects of light on the resistivity of graphene.

机译：残留气体对ZnO，GaN，ZnS纳米结构的场发射特性的影响，以及光对石墨烯电阻率的影响。

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

In this dissertation, I present that at a vacuum of 3x10 -7 Torr, residual O2, CO2, H2 and Ar exposure do not significantly degrade the field emission (FE) properties of ZnO nanorods, but N2 exposure significantly does. I propose that this could be due to the dissociation of N2 into atomic nitrogen species and the reaction of such species with ZnO. I also present the effects of O 2, CO2, H2O, N2, H2, and Ar residual gas exposure on the FE properties of GaN and ZnS nanostructure. A brief review of growth of ZnO, GaN and ZnS is provided. In addition, Cs deposition on GaN nanostructures at ultra-high vacuum results in 30% decrease in turn-on voltage and 60% in work function. The improvement in FE properties could be due to a Cs-induced space-charge layer at the surface that reduces the barrier for FE and lowers the work function.;I describe a new phenomenon, in which the resistivity of CVD-grown graphene increases to a higher saturated value under light exposure, and depends on the wavelength of the light---the shorter the wavelength, the higher the resistivity. First-principle calculations and theoretical analysis based on density functional theory show that (1) a water molecule close to a graphene defect is easier to be split than that of the case of no defect existing and (2) there are a series of meta-stable partially disassociated states for an interfacial water molecule. Calculated disassociation energies are from 2.5 eV to 4.6 eV, that match the experimental observation range of light wavelength from visible to 254 nm UV light under which the resistivity of CVD-grown graphene is increased.
机译：在本文中，我提出在3x10 -7 Torr的真空下，残留的O2，CO2，H2和Ar暴露不会显着降低ZnO纳米棒的场发射（FE）性能，而N2暴露会显着降低。我认为这可能是由于N2分解成原子氮物质以及此类物质与ZnO的反应。我还介绍了O 2，CO 2，H 2 O，N 2，H 2和Ar残留气体暴露对GaN和ZnS纳米结构的FE特性的影响。简要回顾了ZnO，GaN和ZnS的生长。另外，超高真空下在GaN纳米结构上的Cs沉积导致导通电压降低30％，功函数降低60％。 FE性能的改善可能是由于表面Cs诱导的空间电荷层减少了FE的势垒并降低了功函。我描述了一种新现象，其中CVD生长的石墨烯的电阻率增加到曝光下的饱和值越高，并且取决于光的波长-波长越短，电阻率越高。基于密度泛函理论的第一性原理计算和理论分析表明：（1）接近石墨烯缺陷的水分子比不存在缺陷的情况更易于分裂，（2）存在一系列的亚甲基界面水分子的稳定的部分解离态。计算出的离解能为2.5 eV至4.6 eV，与可见光至254 nm紫外光的实验波长范围相匹配，在该范围内CVD生长的石墨烯的电阻率增加。

著录项

  • 作者

    Mo, Yudong.;

  • 作者单位

    University of North Texas.;

  • 授予单位 University of North Texas.;
  • 学科 Condensed matter physics.
  • 学位 Ph.D.
  • 年度 2014
  • 页码 131 p.
  • 总页数 131
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号