Date
2023Metadata
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Dissertation
Highly Selective Gas Sensors using GaN Nano Wires
Abstract
Over recent years, a variety of nanostructure gas sensor designs have been published, utilizing structures such as planar high electron mobility transistors (HEMTs) and one-dimensional structures like nanorods, nanowires, and nanotubes. Even though these sensors have demonstrated responses to certain target gases, generally all designs also showed cross-sensitivites to other gases in the same order of magnitude. However, a concept for developing highly selective nanowire sensors that are sensitive to only one specific gas species and meet the requirements for industrial mass production is still missing. Sensors based on one-dimensional structures are more promising for the detection of low gas concentrations compared to planar designs due to their higher surface-to-volume ratios. Gallium nitride (GaN) is a wide band gap (≈ 3:4 eV) semiconductor material which recently has been focused on as a candidate for high performance gas sensors due to its high carrier saturation velocity, fast electron mobility, and thermal, mechanical, and chemical stability. On the other hand, studies on surface-functionalized tin oxide (SnO₂) nanowires, previously conducted by our project partners, have demonstrated encouraging results regarding sensor selectivity. Moreover, the theoretical insights gained from these studies identify the Fermi Level of the semiconductor-functional group system as a key parameter that could be engineered for the fabrication of gas sensors tailored to single gas species. Translating these strategies onto GaN nanowires could help overcome the impediments inherent in the utilization of SnO₂, such as irregular wire growth, bending, weak reproducibility and predictability of sensor responses. This thesis investigates macroscopic device simulations of GaN nanowires in the context of gas sensing applications. To this end, straight nanowires with bottom and top contacts are modeled as the basic device geometry. Various sensor structures, including resistors, pn-diodes, and transistor-like npn-junctions, are investigated to identify optimal sensor designs in terms of structure, doping concentrations, and morphology. Numerical modeling is performed using a proprietary semiconductor drift-diffusion solver.
Additional Information
Deutscher Titel: Hochselektive Gas-Sensoren auf der Basis von GaN NanodrähtenCitation
@phdthesis{doi:10.17170/kobra-2024071710533,
author={Frank, Kristian},
title={Highly Selective Gas Sensors using GaN Nano Wires},
school={Kassel, Universität Kassel, Fachbereich Elektrotechnik/Informatik},
year={2023}
}
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<resource xsi:schemaLocation="http://datacite.org/schema/kernel-2.2 http://schema.datacite.org/meta/kernel-2.2/metadata.xsd"> 2024-08-23T08:48:08Z 2024-08-23T08:48:08Z 2023 doi:10.17170/kobra-2024071710533 http://hdl.handle.net/123456789/15978 Deutscher Titel: Hochselektive Gas-Sensoren auf der Basis von GaN Nanodrähten eng Attribution-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nd/4.0/ Nanodrähte Halbleiter 1D Sensorik GaN Nanowires Semiconductor 1-D Sensors 600 Highly Selective Gas Sensors using GaN Nano Wires Dissertation Over recent years, a variety of nanostructure gas sensor designs have been published, utilizing structures such as planar high electron mobility transistors (HEMTs) and one-dimensional structures like nanorods, nanowires, and nanotubes. Even though these sensors have demonstrated responses to certain target gases, generally all designs also showed cross-sensitivites to other gases in the same order of magnitude. However, a concept for developing highly selective nanowire sensors that are sensitive to only one specific gas species and meet the requirements for industrial mass production is still missing. Sensors based on one-dimensional structures are more promising for the detection of low gas concentrations compared to planar designs due to their higher surface-to-volume ratios. Gallium nitride (GaN) is a wide band gap (≈ 3:4 eV) semiconductor material which recently has been focused on as a candidate for high performance gas sensors due to its high carrier saturation velocity, fast electron mobility, and thermal, mechanical, and chemical stability. On the other hand, studies on surface-functionalized tin oxide (SnO₂) nanowires, previously conducted by our project partners, have demonstrated encouraging results regarding sensor selectivity. Moreover, the theoretical insights gained from these studies identify the Fermi Level of the semiconductor-functional group system as a key parameter that could be engineered for the fabrication of gas sensors tailored to single gas species. Translating these strategies onto GaN nanowires could help overcome the impediments inherent in the utilization of SnO₂, such as irregular wire growth, bending, weak reproducibility and predictability of sensor responses. This thesis investigates macroscopic device simulations of GaN nanowires in the context of gas sensing applications. To this end, straight nanowires with bottom and top contacts are modeled as the basic device geometry. Various sensor structures, including resistors, pn-diodes, and transistor-like npn-junctions, are investigated to identify optimal sensor designs in terms of structure, doping concentrations, and morphology. Numerical modeling is performed using a proprietary semiconductor drift-diffusion solver. open access Frank, Kristian 2023-04-21 ix, 113 Seiten Kassel, Universität Kassel, Fachbereich Elektrotechnik/Informatik Hillmer, Hartmut (Prof. Dr.) Witzigmann, Bernd (Prof. Dr.) Bangert, Axel (Prof. Dr.) Lehmann, Peter (Prof. Dr.) Gassensor Nanodraht Nanostruktur Galliumnitrid Halbleiter publishedVersion false true </resource>
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