| Summary: | 碩士 === 國立中興大學 === 物理學系所 === 100 === A two-step anodization process was used to fabricate ordered porous anodic aluminum oxide (AAO) on a commercial aluminum alloy with purity 99.5%, followed by heat treatment procedure. The heat treatment exerts an influence on the structure of AAO. The morphologies of both annealed and as prepared AAO films were investigated by field emission scanning electron microscope (SEM). The electrical properties were explored by AC impedance and DC I-V characteristic. The micrograph of SEM reveals a decrease of pore diameter and an increase of wall thickness of the AAO film after heat treatment. This change of structure is explained by the diffusion process of oxygen from atmosphere and aluminum from the barrier layer at the bottom of the AAO film. The fitting results of ac impedance reveal that the capacity of AAO film does not change after heat treatment, and the structure of AAO film can be represented by three series of RC circuits corresponding to barrier layer, porous layer, and branched pore layer respectively. Due to the increasing of defects in branched pore layer after heat treatment, the resistance and capacity of the branched pore layer is decreased. It is found that the space charge limited conduction (SCLC) is able to describe the carrier transport mechanism in AAO films, in addition, the SCLC is influenced by shallow trap before annealing and by deep trap after annealing.
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