| Summary: | 碩士 === 國立臺灣科技大學 === 電子工程系 === 100 === ZnO nanowire UV sensors were fabricated by thermal oxidation of metallic zinc strips. A trench was cut through the metallic zinc strip by focused ion beam and subsequent thermal oxidation at 450?aoC results in the formation of ZnO nanowires across the trench. The diameter of the ZnO nanowire is ~ 70 nm, the growth direction is along the [110] direction and is of single crystalline quality. Room temperature photoluminescence (PL) study shows strong near band edge emission at 377 nm and negligible defect related deep level emission. Variable temperature PL study shows that the room temperature PL emission is due to recombination of free excitons, while at 10 K, the PL is dominated by recombination of surface excitons and exciton bound to neutral acceptors. The ZnO nanowire sensor exhibits a normalized gain of ~ 10^-5 m^2V^-1 under 300 nm illuminations with a riese and decay time of 0.15 and 2.1 seconds, respectively. The responsitivity and UV/Visible rejection ratio are 1.5?e105 A/W and 30, respectively. This extradoinary high photosensing property is due to the high crystalline quality of ZnO [110] nanowires.
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