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dc.contributor.advisorMenon, Reghu
dc.contributor.authorJaiswal, Manu
dc.date.accessioned2010-06-02T10:06:07Z
dc.date.accessioned2018-07-31T06:20:25Z
dc.date.available2010-06-02T10:06:07Z
dc.date.available2018-07-31T06:20:25Z
dc.date.issued2010-06-02
dc.date.submitted2008-12
dc.identifier.urihttp://etd.iisc.ac.in/handle/2005/700
dc.description.abstractCarbon nanotubes show a wide range of transport behavior that varies from ballistic to hopping regime, depending on the nature of disorder in the system. Minute variations in disorder can lead from weak to strong localization, and this yields complex and intriguing features in the analysis of transport data. This dissertation reports an experimental study of charge transport in optically transparent single-wall carbon nanotube (SWNT) networks and field-effect devices. The SWNT network comprises randomly aligned (bundles of) tubes that have both high optical transparency in visible, near-infrared (IR) wavelength range and high electrical conductivity. Various aspects of charge transport in this material including magnetotransport, high electric-field transport and gate induced field-effect are investigated and presented within a consistent framework. The temperature dependence of resistance suggests hopping transport in the network. Since strong localization is observed for the disordered network, the disorder is further characterized by a magnetotransport study and a pulsed electric-field dependence study down to low temperatures (1.3 K). The magnetoresistance (MR) has contributions from two quantum effects -a forward interference mechanism leading to a negative MR and a wavefunction shrinkage mechanism leading to positive MR. The temperature dependence of the coefficient of this negative MR is shown to follow inverse power-law dependence, in accordance with theoretical predictions. The intrinsic parameters obtained from this analysis suggest a transverse localization of charge on the bundle boundaries. The electric-field dependence, measured to high fields, follows the predictions of hopping transport in high electric-field regime. A scaling analysis indicates that electric-field and temperature play similar roles in the transport. The calculated dependence of ‘threshold electric-field’ is also suggestive of this competing process between phonons and electric-field. The applicability of the concept of ‘effective temperature’ is explored for this system; the electric-field induced suppression of MR is studied. The network resistance as well as the optical transparency of the network is modulated with gate voltage using an electrolyte gate dielectric. The gating can tune the absorptions associated with the van Hove singularities in the SWNT DOS and a time response study for this ‘smart window’ is done for the modulation. A novel technique is used to characterize organic and nanotube field-effect transistors and this allows estimation of device parameters such as transconductance and channel impedance. The ac impedance of the SWNT network is also investigated as a possible tool to probe network connectivity. To summarize, the role of disorder in charge transport is investigated for these novel transparent SWNT networks using magnetic-field, electric-field, temperature and field-effect dependent transport measurements.en_US
dc.language.isoen_USen_US
dc.relation.ispartofseriesG22425en_US
dc.subjectCarbon Nanotubesen_US
dc.subjectElectric Charge Transportationen_US
dc.subjectCarbon Nanotube Networks (CNTs)en_US
dc.subjectSingle-Wall Nanotube Networksen_US
dc.subjectCharge Transporten_US
dc.subjectSWNT Networken_US
dc.subject.classificationNanotechnologyen_US
dc.titleCharge Transport In Transparent Single-Wall Carbon Nanotube Networks And Devicesen_US
dc.typeThesisen_US
dc.degree.namePhDen_US
dc.degree.levelDoctoralen_US
dc.degree.disciplineFaculty of Scienceen_US


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