种子层对TiO_2纳米棒阵列取向生长及界面态的影响

Influence of Seed-layer to Orientation of TiO_2 Nanorod Array and Interface State

采用水热法制备了金红石相的单晶TiO2纳米棒阵列,利用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、紫外-可见分光光度计(UV-Vis)以及表面光电压谱仪(SPS)研究了其形貌、结构以及光电性质.通过在不同生长基底上的对比实验发现,F掺杂SnO2导电玻璃基底和种子层对纳米棒阵列的生长起决定作用,TiO2种子层与SnO2∶F基底晶格匹配,有利于晶体外延生长,使TiO2纳米棒阵列的取向性更强.场调制表面光电压测量结果表明,金红石相的TiO2与基底界面处的能带向上弯曲,在FTO/TiO2界面存在大量界面态,这些界面态可能成为光生载流子的复合中心.实验结果表明,引入种子层不仅有利于TiO2纳米棒的取向生长,而且可极大地减少界面态,从而提高电荷的收集效率.

Single crystal TiO2 nanorod arrays grown on FTO substrate were prepared by hydrothermal method.The morphology,structure and photoelectric property were investigated with scanning electron microscope（SEM）,X-ray diffraction spectrum（XRD）,ultraviolet-visible absorption spectrum（UV-Vis） and surface photovoltage spectrum（SPS）,respectively.In the contraction of different arrays with different substrates we found that the FTO substrate had a decisive effect on the growth of nanorod arrays.The lattices of TiO2 seed layer and SnO2∶F matched very well,which helped the epitaxial growth and the orientation of nanorod arrays.According to the field induced surface photovoltage spectroscopy,there was a band upward bending in TiO2 nanorods at the interface of TiO2 and FTO.Introducing seed layer into the process of growth can help the orientation of array,decrease the interface state greatly and provide the potential to increase the collection efficiency of carrier.