Graduate Thesis Or Dissertation
 

Device Fabrication and Characterization for Biological and Radiation Sensing

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https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/1v53k328x

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  • Amorphous indium gallium zinc oxide (IGZO) thin film transistors (TFT) has revolutionized the display industry enabling smaller pixel sizes and higher refreshing rates than traditional amorphous Si: H TFTs. These attributes of IGZO were leveraged to make a field-effect sensing (FES) platform capable of sensing various biomarkers. The sensitivity and selectivity of the sensor to glucose was achieved by functionalizing the IGZO back channel surface with aminosilane groups which were further cross-linked with glucose oxidase (GOx) enzymes. The sensor was integrated with a microfluidic channel, and the sensor response was studied with respect to varying glucose concentrations. An analysis of the sensitivity of the sensor for various gate voltages (VG) was conducted to determine the optimal VG to operate the sensor for continuous glucose sensing. These sensing platforms can be made completely transparent and are compatible for integration onto flexible substrates enabling transparent active-matrix sensing arrays (TASA) where multiple biomarkers can be sensed which will aid next-generation internet of things (IoT) hardware for human health monitoring and analytics. Lead selenide (PbSe) nanocrystalline (NC) particles have a large Bohr radius (~ 46 nm) which enables high quantum confinement effects in relatively larger diameter NC PbSe. As a consequence, the efficiency of charge multiplication (CM) on impact ionization (II) is enhanced for NC compared to bulk PbSe. In addition, a relatively high density of these NC PbSe enables complete transfer of high energy radiation in a relatively thin sensing layer. However, the radiation sensing capability and electronic transport for NC PbSe radiation detectors is impeded by long-chain stabilizing organic ligands on the NC surface as well as the current fabrication methods. In this research, a biphasic ligand exchange process was integrated to the detector fabrication protocol to improve electrical conductivity by reducing interparticle distance and improved packing efficiency. In addition, the fabrication complexity of the radiation sensors was greatly reduced due to solution based ligand exchange, which can be scalable in achieving thick, crack free NC PbSe films. Improved conductivity and Schottky like behavior, which are desirable for good radiation sensing, were demonstrated in the fabricated NC PbSe radiation detector.
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  • 2019-01-18 to 2021-02-19

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