Jumaah, Alaa (2021)
Graphene Based Terahertz Devices.
Technische Universität Darmstadt
doi: 10.26083/tuprints-00019222
Dissertation, Erstveröffentlichung, Verlagsversion
Kurzbeschreibung (Abstract)
Terahertz waves enable many applications such as microscopic imaging with a very high spatial resolution due to the (sub-)mm wavelength. Moreover, many optically opaque materials such as paper, envelopes, clothes, or many kinds of plastic are transparent to terahertz radiation. Additionally, the corresponding photon energy of the terahertz radiation, 1 - 100 meV, is harmless for various materials and biomolecules. Therefore, the terahertz wave is much safer in medical applications compared to X-rays waves. The development of technology to enhance terahertz devices (sources and detectors) was one of the biggest challenges in the terahertz field. Conventional interdigitated photomixers are one of the main efficient devices that can generate and detect terahertz radiation. However, these types of photomixers have many limitations that restricted the operation performance.
This dissertation presents new types of terahertz photomixers based on nanoelectrodes (single and multilayer graphene) that significantly enhance the terahertz output power, detection sensitivity, and operational performance. The nanoelectrodes design enhances the device characteristics directly and the operational performance. The DC measurements of the graphene photomixers indicated highly improved performance as compared to the conventional devices. The graphene photomixers showed a large increase in the generated photocurrent (more than one order of magnitude) and proved the device's reliability under very high bias voltage without damage. The terahertz measurement results of the graphene photomixers clearly enhanced by 30 times due to the effect of high transparency, electrical conductivity, and thermal conductivity of the graphene. The improvement of the terahertz output power in graphene devices compared to the conventional devices leads to potential applications in a higher terahertz frequency range.
This dissertation presents a novel approach to enhance the terahertz output power of the new types of photomixers with hybrid nanoelectrodes based on graphene and silver nanowires. Similar to graphene photomixers, the hybrid nanoelectrodes photomixers recorded even higher generated photocurrent (more than two orders of magnitude), 50 times higher terahertz output power, and device reliability under very high bias voltage without damage as compared to the conventional interdigitated photomixers. In this dissertation, all respective fabrication, characterization, and measurement details are presented and described.
| Typ des Eintrags: | Dissertation | ||||
|---|---|---|---|---|---|
| Erschienen: | 2021 | ||||
| Autor(en): | Jumaah, Alaa | ||||
| Art des Eintrags: | Erstveröffentlichung | ||||
| Titel: | Graphene Based Terahertz Devices | ||||
| Sprache: | Englisch | ||||
| Referenten: | Kusserow, Prof. Dr. Thomas ; Monroy, Prof. Dr. Idelfonso Tafur | ||||
| Publikationsjahr: | 2021 | ||||
| Ort: | Darmstadt | ||||
| Kollation: | 136 Seiten | ||||
| Datum der mündlichen Prüfung: | 26 Mai 2021 | ||||
| DOI: | 10.26083/tuprints-00019222 | ||||
| URL / URN: | https://tuprints.ulb.tu-darmstadt.de/19222 | ||||
| Kurzbeschreibung (Abstract): | Terahertz waves enable many applications such as microscopic imaging with a very high spatial resolution due to the (sub-)mm wavelength. Moreover, many optically opaque materials such as paper, envelopes, clothes, or many kinds of plastic are transparent to terahertz radiation. Additionally, the corresponding photon energy of the terahertz radiation, 1 - 100 meV, is harmless for various materials and biomolecules. Therefore, the terahertz wave is much safer in medical applications compared to X-rays waves. The development of technology to enhance terahertz devices (sources and detectors) was one of the biggest challenges in the terahertz field. Conventional interdigitated photomixers are one of the main efficient devices that can generate and detect terahertz radiation. However, these types of photomixers have many limitations that restricted the operation performance. This dissertation presents new types of terahertz photomixers based on nanoelectrodes (single and multilayer graphene) that significantly enhance the terahertz output power, detection sensitivity, and operational performance. The nanoelectrodes design enhances the device characteristics directly and the operational performance. The DC measurements of the graphene photomixers indicated highly improved performance as compared to the conventional devices. The graphene photomixers showed a large increase in the generated photocurrent (more than one order of magnitude) and proved the device's reliability under very high bias voltage without damage. The terahertz measurement results of the graphene photomixers clearly enhanced by 30 times due to the effect of high transparency, electrical conductivity, and thermal conductivity of the graphene. The improvement of the terahertz output power in graphene devices compared to the conventional devices leads to potential applications in a higher terahertz frequency range. This dissertation presents a novel approach to enhance the terahertz output power of the new types of photomixers with hybrid nanoelectrodes based on graphene and silver nanowires. Similar to graphene photomixers, the hybrid nanoelectrodes photomixers recorded even higher generated photocurrent (more than two orders of magnitude), 50 times higher terahertz output power, and device reliability under very high bias voltage without damage as compared to the conventional interdigitated photomixers. In this dissertation, all respective fabrication, characterization, and measurement details are presented and described. |
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| Status: | Verlagsversion | ||||
| URN: | urn:nbn:de:tuda-tuprints-192229 | ||||
| Sachgruppe der Dewey Dezimalklassifikatin (DDC): | 600 Technik, Medizin, angewandte Wissenschaften > 620 Ingenieurwissenschaften und Maschinenbau | ||||
| Fachbereich(e)/-gebiet(e): | 18 Fachbereich Elektrotechnik und Informationstechnik 18 Fachbereich Elektrotechnik und Informationstechnik > Institut für Mikrowellentechnik und Photonik (IMP) |
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| Hinterlegungsdatum: | 05 Aug 2021 07:33 | ||||
| Letzte Änderung: | 09 Aug 2021 07:28 | ||||
| PPN: | |||||
| Referenten: | Kusserow, Prof. Dr. Thomas ; Monroy, Prof. Dr. Idelfonso Tafur | ||||
| Datum der mündlichen Prüfung / Verteidigung / mdl. Prüfung: | 26 Mai 2021 | ||||
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| Suche nach Titel in: | TUfind oder in Google | ||||
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