Chemical and Physical Graphene Modifications

[摘要] Thisdissertationisinspiredbyrecentprogressinthechemistry,physics,and nanotechnology of graphene, a single layer of carbon atoms. Studying and controllably modifying the electrical properties of graphene while minimizing damagetothelatticecontinuestobeachallengetothescientificcommunity.Chapter 1 focuses on the covalent attachment of molecules with different functional groups to graphene and how functionalization modifies the electrical transport properties of graphene field effect transistors (FET) devices. Functionalization is shown to predominantly induce p-­type doping, undiminished mobility, and increased conductivity at the neutrality point. Physisorbed molecules desorb easily and do not have a significant effect. Statistical analysis enables us to extract trends even though identically fabricated graphene devices can exhibit a wide range of electrical behaviors, emphasizing that conclusions should not be drawnbasedonsingularextremes. In Chapter 2 we present the fabrication and characterization of graphene antidot lattices produced by placing graphene on pre-patterned substrates. While the graphene remains intact atop a periodic well pattern we observe a surface potentialdifferentialinsidevs.outsidethewells.Chapter 3 investigates graphene FETs with multiple neutrality points. We used Raman mapping to determine if multiple local gating fields can be spatially resolved. While we were able to show doping inhomogeneity in graphene devices, there was no obvious difference between devices with one vs. multiple neutrality points.In Chapter 4 we demonstrate a method to grow graphene from solid carbon sources.Iconfirmedthesinglelayernatureoftheproducedgrapheneusingatomic force microscopy (AFM) and fabricated and characterized intrinsic FETs based on solid-­derivedgraphene.InChapter5weproposethatgraphenelayersnucleatealongandunderneath theedgesofexistinggraphenelayerswithacontinuouslayerremainingontop.My AFM characterization of hexagonal graphene onions provided evidence for our proposednucleationmechanism.Chapter 6 is a report on graphene resistor devices that were contributed to anexperimentaboardtheInternationalSpaceStationwhichseekstoinvestigatethe effectsofradiationexposure.Overall, the work accomplished in this dissertation constitutes a step forwardtowardcontrollabledevicebehavioringraphenebasedelectronics.

[发布机构] Rice University

[效力级别] Carbon