14,892 research outputs found
Direct electronic measurement of Peltier cooling and heating in graphene
Thermoelectric effects allow the generation of electrical power from waste
heat and the electrical control of cooling and heating. Remarkably, these
effects are also highly sensitive to the asymmetry in the density of states
around the Fermi energy and can therefore be exploited as probes of distortions
in the electronic structure at the nanoscale. Here we consider two-dimensional
graphene as an excellent nanoscale carbon material for exploring the
interaction between electronic and thermal transport phenomena, by presenting a
direct and quantitative measurement of the Peltier component to electronic
cooling and heating in graphene. Thanks to an architecture including nanoscale
thermometers, we detected Peltier component modulation of up to 15 mK for
currents of 20 A at room temperature and observed a full reversal between
Peltier cooling and heating for electron and hole regimes. This fundamental
thermodynamic property is a complementary tool for the study of nanoscale
thermoelectric transport in two-dimensional materials.Comment: Final version published in Nature Communications under a Creative
Commons Attribution 4.0 International Licens
Polycrystalline graphene and other two-dimensional materials
Graphene, a single atomic layer of graphitic carbon, has attracted intense
attention due to its extraordinary properties that make it a suitable material
for a wide range of technological applications. Large-area graphene films,
which are necessary for industrial applications, are typically polycrystalline,
that is, composed of single-crystalline grains of varying orientation joined by
grain boundaries. Here, we present a review of the large body of research
reported in the past few years on polycrystalline graphene. We discuss its
growth and formation, the microscopic structure of grain boundaries and their
relations to other types of topological defects such as dislocations. The
review further covers electronic transport, optical and mechanical properties
pertaining to the characterizations of grain boundaries, and applications of
polycrystalline graphene. We also discuss research, still in its infancy,
performed on other 2D materials such as transition metal dichalcogenides, and
offer perspectives for future directions of research.Comment: review article; part of focus issue "Graphene applications
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