Device physics and charge transport of field-effect transistors based on advanced organic semiconductors and graphene

dc.contributor.advisorDodabalapur, Ananth, 1963-en
dc.contributor.committeeMemberNeikirk, Dean Pen
dc.contributor.committeeMemberBank, Sethen
dc.contributor.committeeMemberAkinwande, Dejien
dc.contributor.committeeMemberNadkarni, Suviden
dc.creatorHa, Tae-Junen 2012en
dc.description.abstractThis dissertation consists of six chapters: In the first chapter, electrical and material properties and charge transport in organic semiconductors and graphene based field-effect transistors (FETs) are introduced. In the second chapter, device architectures of indenofluorene-phenanthrene copolymer based thin-film transistors (TFTs) are discussed. The combination of recessed source/drain and surface treatments on electrical contact and low-voltage-operated TFTs with solution-processed high-k dielectric are investigated. In the third chapter, device physics and charge transport of diketopyrrolopyrrole-naphthalene copolymer based TFTs are discussed. Top-gate TFTs with the polymer dielectric exhibit mobilities of ~1 cm2/V-s and charge transport measurements in steady-state and under non-quasi-static conditions reveal device physics in dual-gate configuration. In the fourth chapter, device characteristics and charge transport in ambipolar diketopyrrolopyrrole-benzothiadiazole copolymer based TFTs are focused. The ambipolar polymer TFTs possess balanced electron and hole mobilities which are both > 0.5 cm2/V-s. The trap density of states is calculated using two analytical methods developed by Lang et al. and Kalb and Batlogg. In the fifth chapter, charge transport of diketopyrrolopyrrole-thiophene copolymer based TFTs employing 4-point-probe configuration is studied. Such polymer TFTs possess the mobilities of up to 3 cm2/V-s. The activation energy as a function of carrier concentration represents multiple trapping and thermally release model or Monroe-type model of charge transport. In the sixth chapter, transformation of electrical characteristics of graphene FETs with an interacting capping layer of fluoropolymers and pi-conjugated organic semiconductors is investigated. The electrical properties of graphene by wafer-scale chemical vapor deposition can be favorably tuned by fluorocarbon capping methods.en
dc.description.departmentElectrical and Computer Engineeringen
dc.subjectPolymer semiconductoren
dc.subjectDevice physicsen
dc.subjectCharge transporten
dc.subjectField-effect transistorsen
dc.titleDevice physics and charge transport of field-effect transistors based on advanced organic semiconductors and grapheneen and Computer Engineeringen Engineeringen University of Texas at Austinen of Philosophyen
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