| Summary: | 碩士 === 南台科技大學 === 光電工程系 === 102 === In this study, we used anodic alumina as template for deposition of SnO2 and TiO2 by ALD to obtain TiO2/SnO2 core-shell nanord structure and used titanium film on the bottom of nanorods as the conduction layer. Because of the difference of energy band edges of SnO2 and TiO2, the electron carriers can transmit from TiO2 to SnO2 quickly and thus the electron-hole seperation efficiency is improved. We observed the surface morphology of core-shell nanorods by SEM and found that some nanorods delaminated due to stress of titanium film. The stress characteristics of titanium films deposited by e-beam evaporation on aluminum foil, glass and Si at various temperatures were there fore investigated.
The results show that the AAO templates anodized at starting voltage of 120 V with a stair-step decline of 5 V per 10 minutes till 100 V have appropriate straight holes for subsequent deposition of SnO2 and TiO2. According to SEM images, AAO templates were dissolved after 40 h immersing in a solution of 6 wt% phosphoric acid and 2 wt% chromic acid. TiO2/SnO2 core-shell nanord arrays with diameter of 123 nm and height of 5 μm were obtained.
Stress measurement shows that the residual stress of Ti films was tensile. The residual stress of Ti films on aluminum foil was smaller than on other substrates foil was prone to deformation to accommodate the stress. The maximum tensile stress of Ti films happened at deposition temperature of 50℃ for various substrates. The XRD patterns show the higher the deposition temperature, the better the crystallinity of Ti films. After subtracting the thermal stress, the growth stress of Ti films was found to decrease with increasing deposition. Using the 200℃ deposited Ti film as the conduction layer of TiO2/SnO2 nanorod arrays, the delamination issue was solved.
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