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金属氧化物在气氛中的光电响应特性

金属氧化物在气氛中的光电响应特性. 苗朦朦 指导老师：谢长生 教授 材料科学与工程学院. 培养成果. 培养成果. 培养成果. Characterization of Photoelectric Properties of ZnO by I-V Measurement. Characterization of Photoelectric Properties of ZnO by I-V Measurement. Characterization of Photoelectric Properties of ZnO by I-V Measurement. Journal.

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金属氧化物在气氛中的光电响应特性

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  1. 金属氧化物在气氛中的光电响应特性 苗朦朦 指导老师：谢长生 教授 材料科学与工程学院

  2. 培养成果 培养成果 培养成果 Characterization of Photoelectric Properties of ZnO by I-V Measurement Characterization of Photoelectric Properties of ZnO by I-V Measurement Characterization of Photoelectric Properties of ZnO by I-V Measurement Journal Journal Journal Advanced Materials Research (Volume 428) Advanced Materials Research (Volume 428) Advanced Materials Research (Volume 428) Volume Volume Volume Materials Science and Engineering Technology Materials Science and Engineering Technology Materials Science and Engineering Technology Edited by Edited by Edited by Gary Yang Gary Yang Gary Yang Pages Pages Pages 153-158 153-158 153-158 DOI DOI DOI 10.4028/www.scientific.net/AMR.428.153 10.4028/www.scientific.net/AMR.428.153 10.4028/www.scientific.net/AMR.428.153 Citation Citation Citation Meng Meng Miao, 2012, Advanced Materials Research, 428, 153 Meng Meng Miao, 2012, Advanced Materials Research, 428, 153 Meng Meng Miao, 2012, Advanced Materials Research, 428, 153 Online since Online since Online since January, 2012 January, 2012 January, 2012 Authors Authors Authors Meng Meng Miao Meng Meng Miao Meng Meng Miao Keywords Keywords Keywords I-V Curves, LabVIEW, MATLAB, Photoelectric Property, ZnO I-V Curves, LabVIEW, MATLAB, Photoelectric Property, ZnO I-V Curves, LabVIEW, MATLAB, Photoelectric Property, ZnO Abstract Abstract Abstract Experiments with ZnO Metal-Oxide-Semiconductor （MOS） under different circumstances were made to get four different I-V curves. There were four conditions: dark, and tests with the green, blue, ultraviolet LED light. According to references, three parameters B，VB0 and Nbarr could be acquired by fitting lines of the I-V curves using MATLAB and LabVIEW. From their definitions, B, VB0 and Nbarr indicate photoelectric properties of ZnO cooperatively under concrete conditions. VB0, grain boundary potential, is parameter of extrinsic properties of ZnO determined by both ZnO and testing conditions. So VB0 is critical to control the photoelectric properties of ZnO. A smaller VB0, the stronger the photoelectric response of ZnO and the lager the efficiency of photoelectric conversion. Besides, this theory can be expanded to test the photoelectric properties of the other semiconductor materials. And I-V curves can direct the application of these materials efficiently. Experiments with ZnO Metal-Oxide-Semiconductor （MOS） under different circumstances were made to get four different I-V curves. There were four conditions: dark, and tests with the green, blue, ultraviolet LED light. According to references, three parameters B，VB0 and Nbarr could be acquired by fitting lines of the I-V curves using MATLAB and LabVIEW. From their definitions, B, VB0 and Nbarr indicate photoelectric properties of ZnO cooperatively under concrete conditions. VB0, grain boundary potential, is parameter of extrinsic properties of ZnO determined by both ZnO and testing conditions. So VB0 is critical to control the photoelectric properties of ZnO. A smaller VB0, the stronger the photoelectric response of ZnO and the lager the efficiency of photoelectric conversion. Besides, this theory can be expanded to test the photoelectric properties of the other semiconductor materials. And I-V curves can direct the application of these materials efficiently. Experiments with ZnO Metal-Oxide-Semiconductor （MOS） under different circumstances were made to get four different I-V curves. There were four conditions: dark, and tests with the green, blue, ultraviolet LED light. According to references, three parameters B，VB0 and Nbarr could be acquired by fitting lines of the I-V curves using MATLAB and LabVIEW. From their definitions, B, VB0 and Nbarr indicate photoelectric properties of ZnO cooperatively under concrete conditions. VB0, grain boundary potential, is parameter of extrinsic properties of ZnO determined by both ZnO and testing conditions. So VB0 is critical to control the photoelectric properties of ZnO. A smaller VB0, the stronger the photoelectric response of ZnO and the lager the efficiency of photoelectric conversion. Besides, this theory can be expanded to test the photoelectric properties of the other semiconductor materials. And I-V curves can direct the application of these materials efficiently. 毕业论文：《金属氧化物的光电响应特性》

  3. 1 问题 2 思路 3 方法 主要内容

  4. e- e- e- e- e- e- e- e- e- CB hv VB h+ h+ h+ h+ h+ h+ h+ h+ h+ 经典半导体光电响应机理

  5. 经典半导体光电响应机理 Generation: Recombination:

  6. 经典半导体光电响应机理 Generation: 光生电子产生： Recombination: 电子空穴因为消耗，所以有了“寿命” 小注入情况下，复合率为： 光生电子的增加率应为 达到定态时：

  7. ZnO在空气中4.5V UV光照下的光电流曲线图 经典半导体光电响应机理 问题1——时间问题 内禀特性 intrinsic 时间单位ms级以下 经典理论 真空条件 时间单位 s以上 外禀特性 extrinsic 实际测试 气氛条件 问题2——数量问题 经典理论 非平衡多数载流子起决定作用 实际计算 气氛条件下的光电导机理？

  8. 1 问题 2 思路 3 方法 主要内容

  9. 思路 材料光电响应（宏观）

  10. 思路 材料光电响应（微观） 通入空气 通入电流 决定

  11. 思路 e- e- e- e- e- e- e- e- e- CB hv VB h+ h+ h+ h+ h+ h+ h+ h+ h+ 材料光电响应（微观） 加光 决定

  12. 思路 导电模型+晶界势垒模型 平衡时（未加电场） 加电场 Bias dependent sensitivity in metal-oxide gas sensors

  13. 思路 稳态光电导 在光照前后，由于光生电子和空穴的作用，使得VB0发生改变，导致材料电学性能发生变化。 通过对实验曲线的拟合可以获得光照下材料的晶界势垒。

  14. 思路 晶界势垒模型 导电模型 稳态 光电导 动态 光激发过程 化学动力学

  15. O2-浓度稳定 晶界势垒稳定 光电流稳定 动态光电导(光激发过程) 上升过程达数十秒以上 空气 表面气体分子的影响 时间轴单位 O2-的消耗 O2-的产生 产生消耗平衡 反应速率 化学反应动力学 材料特性参数 化学反应速率常数

  16. 反应方程 反应物质浓度 反应量 -x -x+y x-y -y x-y -x+y t=t a-x b-x+y n+x-y m-y n+x-y b-x+y 动态光电导(光激发过程) (a) (b)

  17. 1 问题 2 思路 3 方法 主要内容

  18. 实验 实验材料 ZnO、WO3、SnO2纯成分点 实验步骤 稳态光电导： 1.弱光条件下安装器件，通入干燥空气。 2.打开光源，选择光源激发电压为4.5V，持续照射30min。 3.进行I-V曲线测试，IV曲线扫描从0V到10V，步长为0.001V。 4.测试时，室温在20摄氏度（开启空调） 动态光电导： 1.开启空气发生器，开启计算机和测试系统电源，并预热5min。 2.将测试样本放入测试腔，并盖好测试腔盖。测试前以1000SCCM流速保证腔体内通入干燥空气5min。 3.测试时，测试电压为2V，每一周期的测试时间为10min。5s时清零，10s加偏压，30s加光，300s断光，590s断电压。整个过程在密闭腔体中进行，控制流量为1000SCCM，选用LED紫外光源。

  19. ZnO稳态光电导 测试曲线及拟合曲线图

  20. SnO2稳态光电导 测试曲线及拟合曲线图

  21. WO3稳态光电导 测试曲线及拟合曲线图

  22. 材料参数比较 不同材料展现了不同的变化！体现不同材料的特点

  23. 动态光电导(光激发过程) 图1 空气中4.5V -UV光照下ZnO的I(t)曲线拟合图

  24. 动态光电导(光激发过程) 图2 空气中4.5V -UV光照下SnO2的I(t)曲线拟合图 图2 空气中4.5V -UV光照下SnO2的I(t)曲线拟合图

  25. 动态光电导(光激发过程) 图3 空气中4.5V -UV光照下WO3的I(t)曲线拟合图 图3 空气中4.5V -UV光照下WO3的I(t)曲线拟合图

  26. 总结 稳态电导研究 1.通过对光电导的现象的分析可以推出光激发稳态模型； 2.通过对实验数据的拟合可以获得材料的特性。 光激发过程研究 • SnO2的拟合度最好。说明SnO2符合光电导模型和理论。 2. ZnO和WO3的拟合效果稍差，原因可能是： 光激发过程是个多级反应或者不同时间段，反应级数不同。

  27. 致谢 感谢启明学院为我提供珍贵的平台，让我有机会在本科阶段就体验科研的过程； 感谢谢长生教授的悉心指导，导师渊博的知识、严谨的治学态度、忘我的工作热情、严于律己的风范和优秀的品德为学生树立了典范； 感谢李华曜师兄一直以来的帮助、关心和教导 ，如师长，更是兄长。

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