Fabrication of Aluminum-Doped Zinc Oxide (AZO) Based Gas Sensors

  • 紀 承佑

Student thesis: Master's Thesis

Abstract

With the development of industry people's daily life is full of more and more industrial products which can release volatile organic compounds (VOCs) in indoor air Most of the VOCs which are exposed to people for some time pose a threat to human health when the concentration reaches a certain degree Therefore people also gradually focused on gas sensors Nowadays gas sensors based on metal oxide semiconductor materials have attracted increasing interests due to their simple implementation low cost high compatibility with semiconductor processing and good reliability for real-time applications Furthermore it is well known that high sensitivity rapid response and excellent selectivity are three most important properties for oxide semiconductor gas sensors Aluminum-doped zinc oxide (AZO) based gas sensors have its merits such as environmental friendliness low cost good compatibility excellent selectivity high sensitivity and so on Consequently Aluminum-doped zinc oxide (AZO) was employed as gas sensors in this study and analyzed its compositions structures and atomic bonding by x-ray diffractometer (XRD) atomic force microscope (AFM) scanning electron microscope (SEM) energy dispersive spectrometer (EDS) and fourier transform infrared spectroscopy (FT-IR) First the Cr/Pt interdigitated electrodes were fabricated on a sapphire substrate by thermal evaporation Then the AZO sensing layer was deposited by radio-frequency (RF) sputtering Finally the crystalline of AZO was improved by rapid thermal annealing (RTA) and gas sensing properties were discussed However the normal nickel oxide gas sensor had bad selectivity on the different gas concentration So that we utilized different catalytic metal which could induce selectivity to composite AZO film Then palladium and platinum catalytic metal film by thermal evaporation could effectively catalytic hydrogen and ammonia gas The result both hydrogen and ammonia gas had excessive sensing property Finally Au nanoparticles were deposited on the AZO sensing film structure Au nanoparticles were excellent catalyst for formaldehyde and formed more active sites and structures with large surface area that facilitated gas transmission and reaction on the surface of the materials Thus the addition of Au nanoparticles actually enhances the sensitivity and improves formaldehyde sensing property
Date of Award2017 Aug 1
Original languageEnglish
SupervisorWen-Chau Liu (Supervisor)

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