Enhancing terahertz photoconductive switches using nanotechnology

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dc.contributor.authorHeshmat Dehkordi, Barmak
dc.contributor.supervisorDarcie, Thomas Edward
dc.date.accessioned2013-03-27T20:04:15Z
dc.date.available2014-03-02T12:22:03Z
dc.date.copyright2012en_US
dc.date.issued2013-03-27
dc.degree.departmentDepartment of Electrical and Computer Engineering
dc.degree.levelDoctor of Philosophy Ph.D.en_US
dc.description.abstractIn this thesis we use three main approaches to enhance the performance of terahertz photoconductive switches (THz PC switches). We first propose two novel materials (GaBiAs and carbon nanotubes) for the substrate. The resulting enhancement in THz emission and reception are significant for GaBiAs. As thoroughly analyzed and addressed in Chapter 2, both the emission bandwidth and the emission amplitude of the device are improved by these materials. A systematic study of CNTs predicts 2 orders of magnitude enhancement in THz emission and one order of magnitude enhancement in THz reception. Experimental results for GaBiAs indicate 0.5 THz increase in bandwidth and 68% increase in the emitted THz wave amplitude. The bandwidth enhancement is in comparison to premium commercial devices. The optical excitation of the PC switch is studied and optimized next as the second enhancement approach (Chapter 3). The study presented in Chapter 3 provides an insight on the subwavelength dynamics of the optical excitation E-field at the edge of the electrodes. The study reveals that majority of the fast photocarriers are collected at the edge of the electrode in a subwavelength scale area. This insight leads to optimization of illumination profile and also the third enhancement approach, namely, the enhancement of electrode structure (Chapter 4). In Chapter 4 we have engineered the electrodes down to nanometer scale. This significantly enhances the optical excitation of the substrate and also overcomes the undesired properties of some substrate materials such as long carrier lifetime. Fabricated devices and fabrication processes are assessed in Chapter 5. Results (Chapter 6) highlight more than two orders of magnitude enhancement for nanostructures on GaAs.en_US
dc.description.proquestcode0544en_US
dc.description.scholarlevelGraduateen_US
dc.identifier.bibliographicCitationB. Heshmat, H. Pahlevaninezhad,Y. Pang, M. Masnadi, R. Lewis, T. Tiedje, R. Gordon and T. E. Darcie "Nanoplasmonic terahertz photoconductive switch on GaAs",Nanoletter, Vol. 12, Iss.12, pp.6255–6259 (2012).en_US
dc.identifier.bibliographicCitationB. Heshmat, H. Pahlevaninezhad, and T.E. Darcie "THz detection with carbon nanotube based photoconductive switches: An assessment of capabilities and limitations", IEEE Photonics Journal, Vol. 4, Iss. 3, pp.970-985,(2012).en_US
dc.identifier.bibliographicCitationB. Heshmat, H. Pahlevaninezhad, M. C. Beard,C. Papadopoulos and T.E. Darcie,"Single wall carbon nanotubes as base material for THz photomixing: A Theoretical study from input power to output THz emssion", Optics Express, Vol. 19, Iss. 16, pp.15077-15089 (2011).en_US
dc.identifier.bibliographicCitationB. Heshmat, D. Li, T. E. Darcie, R. Gordon, " Tuning plasmonic resonances of an annular aperture in metal plate " Optics Express, Vol. 19, Iss. 7, pp. 5912–5923 (2011).en_US
dc.identifier.bibliographicCitationH. Pahlevaninezhad, B. Heshmat, T. E. Darcie, Fellow, IEEE, "Advances in THz technology", IEEE Photonics, Vol. 3, Iss. 2, pp. 307-310, 2011.en_US
dc.identifier.bibliographicCitationH. Pahlevaninezhad, B. Heshmat and T. E. Darcie "Efficient THz slotline waveguides" Optics Express, Vol. 19 Iss. 26, pp.B47-B55 (2011)en_US
dc.identifier.urihttp://hdl.handle.net/1828/4498
dc.languageEnglisheng
dc.language.isoenen_US
dc.rights.tempAvailable to the World Wide Weben_US
dc.subjectTerahertz waveguidesen_US
dc.subjectNanotechnologyen_US
dc.subjectCarbon nanotubesen_US
dc.subjectTRTSen_US
dc.subjectNanoplasmonicen_US
dc.subjectPhotoconductive switchen_US
dc.subjectPhotomixeren_US
dc.subjectGaAsen_US
dc.subjectGaAsBien_US
dc.titleEnhancing terahertz photoconductive switches using nanotechnologyen_US
dc.typeThesisen_US

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