一维氧化锌纳米材料的光电性能及器件应用基础研究

发布时间：2018-03-03 02:35

  本文选题：氧化锌　切入点：纳米线　出处：《北京科技大学》2015年博士论文　论文类型：学位论文

【摘要】：ZnO是一种直接宽带隙半导体材料,禁带宽度在室温下约为3.37eV,天然呈n型半导体导电特性,常见的结构为六方纤锌矿结构。而一维ZnO纳米材料独特的纳米效应极大地改善了其光电性能,在太阳能电池、紫外探测、光解水制氢等领域显示出了广阔的应用前景。本文采用水热法和化学气相沉积法制备了不同形貌的一维ZnO纳米材料,并深入研究了其自驱动光电响应机理。在此基础上,系统地探究了光敏化剂ZnIn2S4和CdS对一维ZnO纳米材料光电化学性能的影响。 分别用水热法和化学气相沉积法制备了ZnO纳米线阵列和ZnO纳米线。合成的一维ZnO纳米材料都具有六方纤锌矿结构,沿[0001]方向生长,结晶质量高,缺陷少。利用实验和模拟相结合的方法推算出了化学气相沉积法制备的单根ZnO纳米线的电子浓度和电子迁移率分别为1.06×1017cm-3和1.68cm2v-1s-1。 研究了单根ZnO纳米线和p型硅薄膜所形成的异质pn结的自驱动光电响应性能。电学性能测试表明,该异质结有明显的整流特性,整流比高达103,按照热电子发射理论计算,其理想因子为2。异质结在负偏压时对紫外光和可见光都有响应,在正偏压时,只对紫外光有响应。零偏压时,对紫外光的响应灵敏度达到2×104,对可见光的响应灵敏度为5×103,响应时间约为7.4ms。零偏压时的光电流和入射光的强度成平方根关系,开路电压与入射光的强度成对数关系。 分别研究了ZnO纳米线网和ZnO纳米线阵列的自驱动光电响应性能。ZnO纳米线网和Pt电极之间形成肖特基接触,零偏压时对紫外光的响应灵敏度达到800。构建了Pt/ZnO纳米线阵列/Pt结构自驱动紫外探测器,器件两端的肖特基势垒高度不同引起了自驱动现象。当势垒高度差为30meV时,器件对紫外光的响应灵敏度达到475。考察了温度对Al/ZnO纳米线阵列/Pt结构单肖特基型自驱动紫外探测器性能的影响。温度低于340K时,光电流随温度升高而增大,温度继续升高,光电流减小。温度高于420K时,电极被氧化,器件发生损坏。 研究了ZnO纳米线阵列／还原氧化石墨烯(RGO)/ZnIn2S4异质结构的光电化学性能。结构分析表明,生成的ZnIn2S4属于六方晶系。经过还原处理后,RGO中含氧官能团的量降为27%。ZnO纳米线阵列复合了RGO和ZnIn2S4之后,对可见光的吸收能力明显增强,在500nm处出现较弱的吸收峰。该异质结构的光转氢效率比纯ZnO纳米线阵列提高了2倍,达到了0.46%。RGO的引入增加了光阳极的表面积,促进了光生载流子在ZnO和ZnIn2S4之间的传输。另外,ZnIn2S4增强了光阳极对可见光的吸收效率,进而提高了其光转氢效率。 研究了3D树枝状ZnO/CdS复合材料的光电化学性能。3D树枝状ZnO/CdS复合材料的光转氢效率比纯ZnO纳米线阵列有大幅提升,达到了1.62%。3D树枝状结构的ZnO纳米线阵列具有更高的表面粗糙度和更大的表面积,这增强了光阳极的光吸收能力,促进了载流子在固／液界面的传输。同时,CdS的引入提高了光阳极在可见光区域的光催化活性,CdS和ZnO之间形成的空间电场,加速了光生载流子的分离。另外,本文还研究了3D树枝状ZnO/CdS复合材料的光腐蚀问题,并用原子层沉积法(ALD)在光阳极表面沉积Ti02保护层,提高了其光电化学稳定性。
[Abstract]:ZnO is a direct wide band gap semiconductor material, the band gap at room temperature is about 3.37eV, a natural conductive properties of N type semiconductor, a common structure for the six wurtzite structure. And the effect of nano ZnO nanomaterials were unique to improve the photoelectric properties in solar cell, UV detection, field water photolysis shows a broad application prospect. This paper adopts the hydrothermal method and chemical vapor one-dimensional ZnO nanomaterials with different morphologies were prepared by deposition, and in-depth study of its self driving photoelectric response mechanism. On this basis, systematically explores the photosensitizing agents ZnIn2S4 and CdS on ZnO nanowires the photoelectrochemical properties of the material.
Respectively using hydrothermal method and chemical vapor ZnO nanowires and ZnO nanowires were prepared by deposition. One dimensional ZnO nano materials synthesis has six wurtzite structure. The growth along the [0001] direction, high crystalline quality, less defects. On the basis of experiment and simulation to calculate the electron density and electron transfer the chemical vapor deposition of single ZnO nanowires prepared by the rate of 1.06 * 1017cm-3 and 1.68cm2v-1s-1.
Study of single ZnO nanowire and P type silicon thin film formed by PN heterojunction self driving photoelectric response performance. Electrical performance tests show that there are clear rectifying properties of the heterojunction, rectifying ratio as high as 103, calculated in accordance with the thermionic emission theory, the ideal factor is in the negative bias are in response to ultraviolet light and 2. in the visible light heterojunction, positive bias, only response to UV light. The zero bias, sensitivity to UV light reached 2 * 104, the response sensitivity of visible light is 5 * 103, the response time is about the photocurrent and incident light 7.4ms. zero bias when the intensity of the relationship between the square root. The open circuit voltage and the intensity of the incident light into a logarithmic relationship.
Self driving photoelectric response Schottky contact formed between the properties of.ZnO nanowires and Pt nanowires of ZnO electrode and ZnO nanowire arrays were studied. The zero bias sensitivity to UV light reached 800. constructed self driven UV detector of Pt/ZnO nanowire arrays /Pt, Schottky barrier devices at both ends of the different height caused by self driving phenomenon. When the barrier height difference is 30meV, sensitivity to UV device reached 475. to investigate the effect of temperature on Al/ZnO nanowire arrays /Pt structure of single Schottky type self driven UV detector performance. The temperature is lower than 340K, the photocurrent increases with the temperature, the temperature continues to rise, the light current temperature decreases. Above 420K, the electrode is oxidized, device damage.
Research on ZnO nanowire arrays / reduced graphene oxide (RGO) photoelectrochemical properties of /ZnIn2S4 heterostructures. The structural analysis shows that the generated ZnIn2S4 belongs to the six party system. After reduction treatment, after oxygen containing functional groups in RGO was reduced to 27%.ZnO composite nanowire arrays RGO and ZnIn2S4, the visible light absorption ability increased, there was an absorption peak at 500nm is weak. The heterostructure light transfer efficiency of hydrogen than pure ZnO nanowires increased 2 times, reaching the introduction of 0.46%.RGO increases the light anode surface area, promote the transfer of the photogenerated carriers between ZnO and ZnIn2S4. In addition, ZnIn2S4 enhanced the absorption the efficiency of light anode of visible light, and then increase the light conversion efficiency of hydrogen.
Study on the photoelectrochemical properties of.3D dendritic ZnO/CdS composite 3D dendritic ZnO/CdS composite light conversion efficiency of hydrogen than pure ZnO nanowire arrays have increased dramatically, reaching ZnO nanowires 1.62%.3D dendritic structure array has higher surface roughness and larger surface area, which enhances the ability to absorb light the anode of light, to promote the transfer of carriers in solid / liquid interface. At the same time, the introduction of CdS improves light anode photocatalytic activity in the visible region of the space electric field is formed between CdS and ZnO, accelerates the separation of photogenerated carriers. In addition, this paper also studied the light corrosion problem of dendritic 3D ZnO/CdS composite material, and using atomic layer deposition (ALD) deposited on the anode surface light Ti02 protective layer, improves the photoelectric chemical stability.

【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TB383.1;O614.241

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