Structural, optical and sensing characteristics of ZnO nanorods grown on different substrates.

• Main Authors: Chih-En Tsai, 蔡至恩
• Other Authors: Fang-Hsing Wang
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/18245944442919865729

碩士 === 國立中興大學 === 光電工程研究所 === 103 === In this study, wet etching was used to produce patterned ZnO seed layer arrays, then the ZnO nanorods were grown by hydrothermal method. The different growth times (30-90 min) and concentrations of zinc acetate solution (0.01-0.04 M) were performed to grow ZnO nanorods, then the thermal evaporation method was used to deposit 350 nm-thick Al interdigitated electrodes as M-S-M gas sensors and UV light detectors. From the SEM analysis, there were significant differences between the ZnO nanorods grown on different substracts. The maximum surface area of the ZnO nanorod was found with zinc acetate solution of 0.03 M and growth time of 60 min. The XRD analysis shows that the ZnO seed layer and the nanorods are typical wurtzite structures with preferred orientation along the (002) plane. The sample prepared with zinc acetate solution of 0.04 M and growth time of 60 min achieved the highest (002) peak intensity from XRD analysis and the highest UV light intensity from PL measurement. The highest responses were obtained as the ZnO nanorods grown for 60 min with zinc acetate solution of 0.03 M on glass and sapphire substrates because of their large total surface area. The gas sensing response increased with the increasing measurement temperature or gas concentration, and the highest sensing response of the devices on different substrates were obtained under the temperature of 300 °C and the gas concentration of 2000 ppm regardless of H2 and CO gas. The highest gas sensing responses of 1.91 and 1.85 for H2 and CO were found at the concentration of 2000 ppm on glass substrates. The shortest response times of 80 s and 115 s for H2 and CO were found at the concentration of 2000 ppm on sapphire substrates. Stability test of sensors shows significant decrement (20-25% ) of the gas sensing responses after 30 and 6 days in Ar and air atmospheres, respectively. For ZnO nanorods as UV light detectors, the photo response decreased with the increase of the concentration of zinc acetate solution. The highest response of 15 was found on the ZnO nanorods grown for 60 min with zinc acetate solution of 0.01 M on sapphire substrates.