| Summary: | 碩士 === 國立成功大學 === 微電子工程研究所 === 104 === In this thesis, the optoelectronic characteristics of ZnO nanorods grown by hydrothermal method are discussed. There are two different device, one is ultraviolet photodetector, and the other is field emission device. The dissertation can be divided into two parts; the first is the application of ultraviolet photodetector and field emission device based on ZnO nanorods. The performance is enhanced due to use aluminum dopant. The second part is ZnO nanorods ultraviolet photodetector with different growth pressures. The influences of ZnO nanorods with different growth pressure are investigated.
In the first part, the ZnO nanorods are fabricated by hydrothermal growth method. By adding a precursor of aluminum nitrate, the aluminum doped ZnO nanorods are successfully synthesized. Aluminum doped ZnO nanorods have Wutrzite surface morphology. Aluminum doped ZnO nanorods is a single crystal structure. The ultraviolet photodetectors based on aluminum doped ZnO nanorods has photo to dark current ratio of 1.4×103. For a given bias 1V,the responsivity is 181 A/W, and the UV-to-Visible ratio is 1.51×103. The noise Equivalent power and detectivity is 1.17×10-11 W and 4.03×1012 cm·Hz0.5W−1, respectively. Also, the field emission device of aluminum doped ZnO nanorods is developed. Under dark condition, the turn-on electric field is 2.35 V/μm, the field enhancement factor is 5708. With UV illumination, the turn-on electric field is reduced to 2.35 V/μm, and the field enhancement factor is enhanced to 10173. The performances are enhanced because aluminum doping can increase the carrier concentration
In the second part, the characteristics of ZnO nanorods fabricated by hydrothermal growth method with different growth pressure are compared. The ZnO nanorods have similar surface morphology. By photoluminescence spectroscopy, it finds that the ZnO nanorods grown with higher pressure have lower defect density. The photo-to-dark current ratio of ZnO nanorods of sample P2 is 216. For a given bias 1V, the responsivity and UV-to-Visible ratio of P2 sample is 40A/W, and 1.58×103respectively. The noise Equivalent power and detectivity is 7.53×10-11 W, and 6.30×1011cm·Hz0.5W−1, respectively. The ZnO nanorods with higher growth pressure shows better performance.
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