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首页> 外文学位 >Electron transport mechanism of titania chains in the framework of titanosilicates ETS-4 and ETS-10.
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Electron transport mechanism of titania chains in the framework of titanosilicates ETS-4 and ETS-10.

机译：钛硅酸盐ETS-4和ETS-10框架中二氧化钛链的电子传输机理。

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Current techniques for preparation of low-dimensional devices present technical difficulties and concomitant costs. This is especially true in the fabrication of aligned quantum wire arrays. Microporous crystalline titanosilicate materials, ETS-4 and ETS-10, are hypothesized to have naturally occurring quantum wires in their framework. They contain monatomic titania chains (...Ti-O-Ti-O-Ti...) isolated from each other by a highly siliceous matrix. These titania chains (∼ 6.7 A in diameter) in ETS-4 run in only the b direction, while they run in both a and b directions in ETS-10. Electron transport properties of titania chains --as hypothesized quantum wires- in the framework of individual ETS-4 and ETS-10 crystals were studied. Current-voltage performance (I-V curves) of both ETS-4 and ETS-10 were investigated at room temperature by placing 2 microprobes on the surface of the individual crystal. It was verified that conduction occurs through the defects in titania chains. Furthermore, the main feature of the current-voltage curve was identified as a current peak due to resonant electron tunneling between titania chains through the insulating layer. Peak to Valley Ratio (PVCR) for 15mu interval was determined as 3.4 and 5.4 for ETS-4 and ETS-10, respectively. It was observed that the PVCR's are decreasing with increasing intervals in the direction of titania chains and for intervals larger than 150mu (ETS-4 only) these current peaks disappeared. Current-voltage curves were also obtained in the dimension/direction where there are no titania chains. The observed current jumps with a higher PVCR supports the hypothesis of resonance electron tunneling through insulating layer of SiO4. Low temperature current-voltage behavior of ETS-4 was investigated by performing the device integration of large individual crystal. Non linear I-V behavior at low voltages was observed. These nonlinear curves were attributed to electron transport through discrete titania chains via tunneling. Current values were observed to be decreasing with decreasing temperatures as expected for bulk semiconductors. However, at higher voltages, similar to the results obtained by probe station at room temperature, current jumps followed by negative differential resistance was observed. PVCR of the peaks were observed to be increasing and peaks shifted to higher resonance voltage values with decreasing temperature. Increase in PVCR upon decreasing temperature also supports the hypothesis of resonance tunneling through insulating siliceous matrix. These results taken in total provide a basis for electron transport mechanism of the monatomic titania chains in ETS crystals which can be utilized in future's optoelectronic devices.
机译：用于制备低尺寸设备的当前技术存在技术困难和随之而来的成本。在对准的量子线阵列的制造中尤其如此。假设微孔晶体钛硅酸盐材料ETS-4和ETS-10在其骨架中具有天然存在的量子线。它们包含通过高度硅质基质彼此隔离的单原子二氧化钛链（... Ti-O-Ti-O-Ti ...）。这些在ETS-4中的二氧化钛链（直径约6.7 A）仅沿b方向延伸，而在ETS-10中沿a和b方向延伸。在单独的ETS-4和ETS-10晶体的框架内研究了二氧化钛链的电子传输特性-作为假设的量子线-。通过在单个晶体表面放置2个微探针，在室温下研究了ETS-4和ETS-10的电流-电压性能（I-V曲线）。证实通过二氧化钛链中的缺陷发生传导。此外，电流-电压曲线的主要特征被识别为由于二氧化钛链之间穿过绝缘层的共振电子隧穿而引起的电流峰值。对于ETS-4和ETS-10，在15微米间隔内的峰谷比（PVCR）分别确定为3.4和5.4。观察到，PVCR在二氧化钛链的方向上随着间隔的增加而减小，并且对于间隔大于150mu（仅适用于ETS-4）的间隔，这些电流峰值消失了。在没有二氧化钛链的尺寸/方向上也获得了电流-电压曲线。在较高的PVCR下观察到的电流跃变支持了共振电子隧穿SiO4绝缘层的假设。通过进行大型单个晶体的器件集成，研究了ETS-4的低温电流-电压行为。观察到低电压下的非线性I-V行为。这些非线性曲线归因于电子通过隧穿穿过离散的二氧化钛链。如体半导体所预期的，电流值随着温度降低而降低。但是，在更高的电压下，类似于室温下探针台获得的结果，观察到电流跳变，然后是负差分电阻。观察到峰的PVCR增加，并且随着温度降低，峰移至较高的谐振电压值。随着温度降低，PVCR的增加也支持通过绝缘硅质基质的共振隧穿的假设。总而言之，这些结果为ETS晶体中单原子二氧化钛链的电子传输机理提供了基础，该结构可用于未来的光电设备中。

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