Regensburg 2019 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 16: Graphene II: Excitations and Nanoribbons (joint session O/TT)
TT 16.10: Talk
Monday, April 1, 2019, 17:15–17:30, H24
Chevron-based graphene nanoribbons and heterojunctions by direct contact printing — •Axel Enders1, Jacob D Teeter2, Paulo S Costa2, Gang Li2, and Alexander Sinitskii2 — 1Universität Bayreuth, Physikalisches Institut, 95440 Bayreuth — 2University of Nebraska - Lincoln, Lincoln NE 68588, USA
Atomically precise graphene nanoribbons (GNRs) have been synthesized through a direct contact transfer (DCT) of molecular precursors on Au(111), followed by gradual annealing. This method provides an alternative to the conventional approach for the deposition of molecules on surfaces by sublimation and simplifies preparation of dense monolayer films of GNRs. We performed STM characterization of the precursors of chevron GNRs, and demonstrate that the assemblies of the intermediates of the GNR synthesis are stabilized by π - π interactions. DCT was then used to deposit a mixture of two structurally similar but visually distinct chevron-type molecular precursors. Annealing of the deposited mix resulted in heterojunctions composed of units of chevron GNRs (cGNRs) and new laterally extended chevron GNRs (eGNRs). The electronic properties of these GNRs across the heterojunctions were studied with scanning tunneling spectroscopy. The dI/dV maps show that the impact of heterojunctions as well as structural defects is highly local and usually stays within the corresponding GNR units even if they are bonded to structurally and electronically different neighbors. It is expected that this method of DCT is highly versatile and allows to combine other chevron-type GNRs as well, such as nitrogen-doped cGNRs, into a variety of new GNR heterojunctions.