【作者】 李大鹏；

【导师】 王冠中；

【作者基本信息】 中国科学技术大学 ， 凝聚态物理， 2009， 博士

【摘要】 具有超晶格结构的InMO₃（ZnO）_m同系物化合物,由于拥有优良的光电性能,一直受到人们的关注。近年来,大量的InMO₃（ZnO）_m准一维超晶格纳米线被成功制备。但是到目前为止,所有报道的此类化合物的准一维纳米结构全部为非公度的超晶格纳米线。如何制备形貌更为丰富、公度性更好的InMO₃（ZnO）_m纳米结构,并且对其物理性质进行更深入的研究将是下一步InMO₃（ZnO）_m超晶格纳米材料研究的重点。本论文研究工作以InMO₃（ZnO）_m纳米材料为主要研究对象,从In₂O₃（ZnO）_m平面超晶格纳米带的制备到结构表征、物理性质研究到InGaO₃（ZnO）_m轴向超晶格纳米线的制备与物性等几个方面,开展了一系列工作,具体包括以下几个方面:1.In₂O₃（ZnO）_m平面超晶格纳米带制备与输运性质研究通过化学气相沉积自组装的方法成功制备出In₂O₃（ZnO）_m平面超晶格纳米带。通过分析纳米带从宽面入射的选区电子衍射花样,结合X射线的结果,我们判定出产物中有In₂O₃（ZnO）_m平面超晶格纳米带的生成,其中超晶格的堆垛方向沿纳米带的高度方向。并且给出了In₂O₃（ZnO）_m单斜结构单包与ZnO六方结构单包之间的转换关系,利用单斜结构对纳米带电子衍射花样进行了标定。通过将所得产物包裹在环氧树脂中进行切片处理,我们得到了具有超晶格结构的纳米带很截面高分辨照片,直接证明了产物中超晶格纳米带的生成。通过测量纳米带的Ⅰ-Ⅴ特性,在两端所加电压在-5V到+5V范围内,我们得到了最高达几十微安量级的电流,显示了十分优秀的半导体性能。2.In₂O₃（ZnO）_m平面超晶格纳米带的喇曼性质研究由于超晶格结构的形成改变了ZnO的局域晶体结构,从而会使其振动特性发生改变。我们对比了超晶格纳米带和没有形成超晶格结构的In掺杂ZnO纳米带的喇曼光谱。两者具有明显的不同,相对于In掺杂ZnO纳米带拉曼光谱,In₂O₃（ZnO）_m平面超晶格纳米带的拉曼光谱中出现了一个位于621cm^-1的新的振动模式,并且属于ZnO特征振动模式的E₂（high）峰变弱且变宽。通过分析In₂O₃（ZnO）_m的局域晶体结构,我们认为,该新的振动模式来自于In₂O₃（ZnO）_m晶体结构中In-O层和In/Zn-O交界面处,一个O原子与三个In原子和一个Zn原子键连而形成的振动模式,是In₂O₃（ZnO）_m超晶格结构的特征振动模式。3.InGaO₃（ZnO）_m轴向超晶格纳米线的制备与发光采用化学气相沉积自组装的方法制备了InGaO₃（ZnO）_m轴向超晶格纳米线。高分辨透射电镜照片显示该纳米线具有完美公度的超晶格层状结构,每两层In-O层间夹四层In/Zn-O层。EDS谱显示在In/Zn-O层,有大量的In原子取代了Zn原子。我们在产物中还发现了具有完美公度的InGaO₃（ZnO）₅超晶格纳米线。和侧面向超晶格纳米带的生成。通过分析样品的发光光谱,显示超晶格纳米线的带边发射位置在3.23eV附近,相比于ZnO带隙,超晶格的带隙变窄。4.几种特殊形貌的ZnO纳米结构的制备与物性研究利用直接蒸发ZnO和In₂O₃混合物粉末,我们制备了ZnO纳米盘/纳米带复合结构。纳米盘的宽面为ZnO（0001）极性面,纳米带生长方向沿[11-20],宽面同样为ZnO（0001）极性面。光致发光谱显示,因为In掺杂,ZnO带边发射发生红移至409nm。在不同实验条件下,我们得到了ZnO纳米棒/纳米带的复合结构。通过蒸发ZnO和MnO₂粉末,我们得到了ZnO纳米塔和层状ZnO六棱柱准阵列。X射线衍射结果显示产物为ZnO纤锌矿结构。这些复合纳米结构,丰富了ZnO纳米结构的形貌。更多还原

【Abstract】 The synthesis, characterization and physical properties studying of quasi-one-dimensional （1D） nanomaterials, including nanowires （rods）, nanoribbons （belts）, nanotubes, heterostructure and superlattice nanowires （ribbons） are always the center spots of namomaterials research area. Among these, the preparing and physical properties studying of heterostructure and superlattice nanostructures are of even more important, as it is the critical case for the success of future optical and electronic nanodevice and integrate circuits performance. In recent years, different kinds and different shape of quasi-1D nanomaterials heterostrtures and superlattice have been successfully synthesized.Owing to the better optical and electronic properties, the homogenous compounds of InMO₃（ZnO）_m have attracted much attention recently. Huge improgress have been obtained on quasi-1D InMO₃（ZnO）_m nanomaterials and a large of them have been successfully synthesized. Yet to now, all superlattice nanowires reported are not periodical and little physcial properties such as photoluminescence have been studied. So it is important to prepared periodical InMO₃（ZnO）_m superlattice nanostructures with different shapes and studying their further physical properties. The main contents, focusing on the preparing, characterization, physical properties studying of In₂O₃（ZnO）_m planar superlattice nanoribbons and InGaO₃（ZnO）_m axial superlattice nanowires, are summarized as:1. synthesis and electrical properties studying of In₂O₃（ZnO）_m planar superlattice nanoribbons.By the use of chemical vapor transports self assembly method, we successfully synthesized In₂O₃（ZnO）_m planar superlattice nanoribbons. Combined with XRD results, we verified the formation of In₂O₃（ZnO）₃ planar superlattice nanoribbons by analyzing the SAED pattern with the incident direction of electron beam perpendicular to the wide surface of a nanoribbon. We also give the translational relation between monoclinic cell and ZnO wurtzite cell and successfully index the obtained SAED with monoclinic structure. We mixed the In₂O₃（ZnO）_m planar superlattice nanoribbons with epoxy resin and cross cut the mixture to slices of about 200 run in thickness and obtained cross-sectional HRTEM image of a nanoribbon. The HRTEM image clearly shows the formation of superlattice structures. We also measure theⅠ-Ⅴproperties of the obtained In₂O₃（ZnO）_m planar superlattice nanoribbons and the out put current can reach severalμA level, which is the highest results ever reported.2 Raman property of In₂O₃（ZnO）_m planar superlattice nanoribbonsThe formation of superlattice structures change the local crystal structure of ZnO wurtzite and thus the vibrational property. We compared the Raman spectra of In doped ZnO nanoribbons with and without superlattice structures. Beside the intensity of ZnO characteristic mode E₂（high） getting low and broading, there is a new vibrational mode （AM） around 621cm^-1 in Raman spectra of products containing In₂O₃（ZnO）_m planar superlattice nanoribbons. By the analysis of the local crystal structure of In₂O₃（ZnO）_m planar superlattice nanoribbons, we infer that this new mode is attributed to an O atom that bonded with three In atoms and one Zn atom in a distorted tetrahedron coordinatio in the interface between In-O layer and In/Zn-O layers in the superlattice of nanoribbons and be the characteristic vibrational mode of In₂O₃（ZnO）_m superlattice nanoribbons.3 Synthesis and photoluminescene properties of InGaO₃（ZnO）_m axial superlattice nanowiresWe havealso successfully synthesized InGaO₃（ZnO）₃ axial superlattice nanowires using chemical vapor transport self assembly method. HRTEM images show the nanowires having layered superlattice structure with perfect commensurability and and exactly four In/Zn-O layers between two adjacent In-O layers. EDS spectra indicates that a large amount of Zn atoms in Ga/Zn-O layers.are substituted by In atoms. We have also found some InGaO₃（ZnO）₅ axial superlattice nanowires and InGaO₃（ZnO）_m lateral superlattice nanoribbons formation in the as synthesized products. By the analysis of PL spectra of the as synthesized products, we infer that the peaks around 3.23eV is the near band edge emission of InGaO₃（ZnO）_m superlattice nanowires.4 Syntheis and physical properties studying of several kinds of complexed ZnO nanostructures.We successfully prepared complexed nanostructures of ZnO nanodisks/nanoribbons by directly evaporating the mixture of ZnO and In₂O₃ powders. The wide surface of the nanodisks is ZnO （0001） and the growth direction of ZnO nanoribbons is [11-20] with the wide surface （0001）. The band gap emission redsift to 409nm cause by In doping was obtained in photoluminescence （PL） spectra. Under different experimental condition, we also successfully prepared the complexed nanostructures of ZnO nanorods/nanoribbons.By evaporating the powders of ZnO and MnO₂ displayed at different places, we obtained ZnO nanotowers and ZnO nanorods arrays with layered structures. XRD result indicates the crystal structures of ZnO wurtzite. All the complexed nanostructures obtained above enrich the morphology of ZnO nanostructures.更多还原