Tuning thermoelectric properties of graphene/boron nitride heterostructures

Laith A Algharagholy, Qusiy Al-Galiby, Haider A Marhoon, Hatef Sadeghi, Hayder M Abduljalil, Colin J Lambert
2015 Nanotechnology  
Using density functional theory combined with a Green's function scattering approach, we examine the thermoelectric properties of hetero-nanoribbons formed from alternating lengths of graphene and boron nitride. In such structures, the boron nitride acts as a tunnel barrier, which weakly couples states in the graphene, to form mini-bands. In un-doped nanoribbons, the mini bands are symmetrically positioned relative to the Fermi energy and do not enhance thermoelectric performance significantly.
more » ... ance significantly. In contrast, when the ribbons are doped by electron donating or electron accepting adsorbates, the thermopower S and electronic figure of merit are enhanced and either positive or negative thermopowers can be obtained. In the most favourable case, doping with the electron donor tetrathiafulvalene increases the room-temperature thermopower to −284 μv K −1 and doping by the electron acceptor tetracyanoethylene increases S to 210 μv K −1 . After including both electron and phonon contributions to the thermal conductance, figures of merit ZT up to of order 0.9 are obtained. S Online supplementary data available from stacks.iop.org/NANO/26/475401/mmedia
doi:10.1088/0957-4484/26/47/475401 pmid:26528629 fatcat:7sloiqn6bzfzhpx7et6cewp444