Geometrical Separation of Defect States in ZnO Nanorods and Their Morphology-Dependent Correlation between Photoluminescence and Photoconductivity

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• 作者：Cheolmin Park ; Jihye Lee ; Won Seok Chang
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：July 23, 2015
• 年：2015
• 卷：119
• 期：29
• 页码：16984-16990
• 全文大小：446K
• ISSN：1932-7455

文摘

An understanding of the morphology-dependent correlation between photoluminescence and photoconductivity in nanostructured ZnO is important for elucidating the carrier dynamics and expanding its use in optoelectrical applications. In this study, we investigated this relationship using distinctly different ZnO nanorods with diameters greater than 100 nm, which were produced by a hydrothermal method. Furthermore, in order to study the effects of its defect states on the correlation, we thoroughly characterized the defect states of the ZnO nanorods in terms of the light-penetration depth during photoluminescence. The photoconductivities of the nanorods were measured using light sources with wavelengths of 355, 405, and 532 nm to confirm the influences of the visible-emission-generating defects on carrier transport. We found that the intensity of the near-band-edge emission was almost comparable to the amount of photocurrent generated under ultraviolet (UV) light; this could be attributed to the crystallinity of the inside of ZnO nanorods. However, the concentration of the surface defects resulting from the size and morphology probably had an effect, leading to the observed differences in the photocurrent sensitivity under low-intensity UV light, the dark current level, the amount of photocurrent under a specific wavelength of light within the visible range, and the persistent photoconductivity. The results of this study could aid research on carrier dynamics in nanostructured ZnO and further its use in optoelectronics.