Thermoelectric Effects in Nanoscale Devices

Bottom-up synthesized atomically precise graphene nanoribbons (GNRs) are Designer Quantum Materials, materials in which the properties can be designed and adjusted on-demand. GNRs offer a variety of properties: tunable bandgap, in-situ pn-junction formation, quantum dot behavior, and even exhibit topologically non-trivial phases. This shows that graphene nanoribbons are a versatile platform for novel electronic devices. However, many challenges remain in the device integration of these materials, especially regarding contacting and gating strategies. These two challenges directly enter the thermoelectric figure of merit zT via the electrical conductivity. This thesis covers various aspects of the GNR device integration for thermoelectric characterization. This involves the development of contacting and gating strategies for assessing the electrical conductivity of GNRs. Further, the Seebeck coefficient of GNR based devices is determined using an advanced measurement platform and scheme. Finally, a novel Raman-based method is established to map thermal conductivity. Although the working principle of this method is demonstrated on defect-engineered graphene membranes, it is extendable to films of GNRs.