Academic literature on the topic 'Trivalent elements doped ZnO'

Semiconductor nanostructures, and in particular ZnO nanowires (NWs), have been intensively studied due to their unique properties that allow its implementation in optoelectronic devices such as UV sensors and 1D TFTs. The doping of these NWs with rare earth elements allows to tune its conductivity and optical properties. The present work reports the synthesis and characterization of undoped and europium doped ZnO NWs, produced through solvothermal methods assisted by microwave irradiation (MW) and conventional oven heating (CO). Different doping concentration levels were this way studied. Both synthesis methods were successful in the production of ZnO nanostructures as confirmed by SEM and XRD, and the doping of Eu lead to the formation of Eu(OH)3 nanostructures attached to the ZnO NWs. The MW synthesis lead to the formation of aggregated NWs forming nanoflowers while in the CO route the aggregation was less evident, with more isolated structures, both with average lengths of 6 μm and a very broad size distribution. Optical characterization allowed to extract the band gap (Eg≈3.2 eV). Electrical characterization was conducted on single ZnO NWs, with different alignment methodologies and in NWs with different post-annealing treatments. An optimization of the alignment strategy to add contacts to isolated NWs using conventional photolithography was achieved. In each substrate 6 individual NWs were aligned. After processing, the yield of working devices was still low as concluded from the electrical characterization where it was possible to extract a resistivity value in just 5 of the measured NWs and no trend for the resistivity values was observed. The use of a passivation layer (Parylene-C) on top of the NWs allowed to improve the stability and adhesion of the NW to the substrate. These nanostructures were tested as UV sensors showing a responsivity of 1.5 mA/W, 1.7 mA/W and 53 μA/W for ZnO NWs without annealing, annealing at 300°C and 700°C.

碩士<br>國立高雄應用科技大學<br>機械工程系<br>106<br>In this thesis, the optical and electrical properties of ZnO/Ag/ZnO, ZnO/Mo/ZnO and ZnO/Mo/Ag/ZnO multilayered films are investigated by different annealing temperatures of 200℃,300℃ and 450℃, respectively. The influences of the process parameters in the three different ZMZ, ZAZ, ZAMZ and different oxide layers on the optical, electrical, surface morphology, cross-section, and structural properties of the multilayered as well as the sheet resistance and figure of merit were analyzed. The results showed that the thinner multilayer film ZMZ had the lowest resistivity of 6.44x10-3 (Ω-cm) at annealing temperature 300℃, and the maximum transmittance is up to 87.3%. Meanwhile the Lt.ZAZ multilayered film can get the lowest resistivity 3.95x10-5 (Ω-cm) at annealing temperature 450℃, and the maximum transmittance is more than 88.4%. The Lt.ZAMZ multilayered film can obtain the lowest resistivity 4.30x10-5 (Ω-cm) at annealing temperature 300℃, and the maximum transmittance rate is more than 73.3%.Finally, the figure of merit analysis of multilayered films was performed at annealing temperature 300℃ as the best quality was 2.60×10-2(Ω-1) based on thinner ZAZ.