Study of ZnO and WO3 nanostructure green energy gas sensor

  • 林 志鴻

Student thesis: Doctoral Thesis


  In this dissertation we use Vapor Phase Transport Deposition (VPTD) to produce ZnO nanowires successfully of the applied poly silicon solar cells and plastice substrates and used sunlight enhancement the response of gas sensor The Through-Silicon Via (TSV) technology to produce a multi-functional sensor achieve the low power consumption Ultimately we used the hot wire chemical vapor deposition (HWCVD) method to produce WO3 nanoparticles and successfully use MEMS technology to fabricate a device integration the microminiaturization and low power consumption   First a transparent ZnO nanowire (NW)-based device for ethanol gas sensing and UV detection was fabricated and deposited on to an indium tin oxide/crystalline silicon (c-Si) solar cell For UV detection the photocurrent increased rapidly with a time constant of about 137 s when UV excitation was applied The photo- current decreased from 3×10-6 to 1 2×10-7 A when the UV light was switched off For ethanol gas sensing UV light was used to increase the quantity of O2? species The ZnO sensor response increased from 8% to 21% when the ethanol gas concentration was increased from 50 to 150 ppm at 53℃ (with the heat generated by the c-Si solar cell) The sensor response was approximately zero without solar illumination The sensor had almost no effect on the transfer efficiency of the solar cell   A low-temperature ZnO nanowire ethanol gas sensor was also prepared on plastic substrate The operating temperature of the ZnO nanowire ethanol gas sensor was reduced to room temperature using UV illumination The experimental results indicate a favorable sensor response at low temperature with the best response at 60℃ The results also reveal that the ZnO nanowire ethanol gas sensor can be easily integrated into portable products whose waste heat can improve the sensor’s response and achieve energy savings while energy consumption can be further reduced by solar irradiation   ZnO nanostructure environmental sensors were prepared via the three-dimensional through silicon via (3D-TSV) technique For 3D-TSV the diameter and length of the Si via were about 200 and 400 μm respectively For nitrogen oxide (NO) the measured responses were around ~12 ~16 and ~20% when the concentrations of the injected NO gas were 20 40 and 60 ppm respectively For humidity and temperature sensing the measured nanowire current increased logarithmically with increasing chamber temperature The response to relative humidity also increased with increasing temperature   Finally a WO3 nanoparticle gas sensor was fabricated using an ICP-assisted hot wire system The results of experiments indicated that the sensitivity became smaller when the measured temperature increased It was also found that the WO3 nanoparticle gas sensor prepared at an annealing temperature of 400℃ had the greatest sensitivity The measured sensitivity for a micro-electro-mechanical system (MEMS) type WO3 nanoparticle gas sensor was found to be around 3 22 3 91 5 02 7 52 11 68 and 15 93 when the operating temperature of the micro-heater was 150 °C and the concentration of injected NO gas was 100 150 200 250 300 and 350 ppb respectively
Date of Award2017 Jul 19
Original languageEnglish
SupervisorShoou-Jinn Chang (Supervisor)

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