Development Of Anodic Aluminum Oxide Templates For Growth Of Cuo Nanorods For Photodetection Divice
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Date
2016-09
Authors
Charour, Khaled Majid
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Abstract
Ordered and hexagonal-shaped nanoporous anodic aluminum oxide (AAO) was successfully grown from 1μm thickness of Al pre-deposited onto Si and ITO/glass substrate using two-step anodization. The growth mechanism of the porous AAO film was investigated by anodization current-time behavior for different anodizing voltages and by microstructural observations using cross-sectional and top view of FESEM imaging. It was found that pores with diameter ranging from 50 to 110 nm and thicknesses between 250 and 1400 nm, were obtained by controlling two main influential anodization parameters: the anodizing voltage and time of the second-step anodization. The optimum conditions of the process variables such as annealing time of the as- deposited Al thin film and pore widening time of porous AAO film were experimentally determined to obtain AAO films with uniformly distributed and vertically aligned porous microstructure. Pore widening via wet-etching treatment at room temperature was found to modify the pore quality of AAO films and reduces the barrier layer on the bottom of AAO pore array facilitating a uniform electrodeposition of nanostructures onto AAO films. In addition, regular hemispherical concave Al surface ensuring the self-ordering of AAO pore can be established when striping is employed for 45 min. Thus, it could be inferred that the duration of wet etching treatment (striping) of Al oxide film performed after the first-step anodization plays a crucial role in the final arrangement of nanopores. X-ray diffraction analysis revealed amorphous-to-crystalline phase
transformation after annealing at temperatures above 800 oC. AFM images showed optimum ordering of the porous AAO films anodized under low voltage condition. AAO films could serve as templates with desired size distribution for the fabrication of CuO nanorod arrays. The results indicated that the morphology of the aligned arrays of CuO nanorods was strongly affected by the duration of etching and the removal of AAO template. This study showed also that the optimum etching duration required to maintain the aligned CuO nanorods without any fracture was approximately 5 min. High performance CuO nanorod arrays/ AAO assembly and free-standing CuO nanorod arrays infrared (IR) metal-semiconductor-metal (MSM) photodetectors were fabricated with Al contact electrodes. The electrical performance and photoelectric response were studied and the results showed that IR photodetectors exhibited a high sensitivity to 808 nm IR laser diode. Both the response and recovery time were found to be fast; i.e. much shorter time compared to other IR photodetectors reported in the literature.
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Development Of Anodic Aluminum Oxide Templates For Growth Of , Cuo Nanorods For Photodetection Divice