| Autor: |
Jiang Z; Department of Physics, National University of Singapore, 2 Science Drive 3, 117551, Singapore., Yam KM; Department of Physics, National University of Singapore, 2 Science Drive 3, 117551, Singapore.; Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore. phyzc@nus.edu.sg., Guo N; Department of Physics, National University of Singapore, 2 Science Drive 3, 117551, Singapore., Zhang L; Department of Physics, National University of Singapore, 2 Science Drive 3, 117551, Singapore.; Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan 250061, China., Shen L; Department of Mechanical Engineering and Engineering Science, National University of Singapore, 117542, Singapore., Zhang C; Department of Physics, National University of Singapore, 2 Science Drive 3, 117551, Singapore.; Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore. phyzc@nus.edu.sg. |
| Abstrakt: |
The standard density functional theory (DFT) based first-principles approach has been widely used for modeling nanoscale electronic devices. A recent experiment, however, reported surprising transport properties of thiol-terminated silane junctions that cannot be understood using the standard DFT approach, presenting a severe challenge for the current computational understanding of electron transport at the nanoscale. Using the recently proposed steady-state DFT (SS-DFT) for nonequilibrium quantum systems, we found that in silane junctions, underlying the puzzling experimental observations is a novel type of intriguing nonequilibrium effect that is beyond the framework of the standard DFT approach. Our calculations show that the standard DFT approach is a good approximation of SS-DFT when silane junctions are near equilibrium, but the aforementioned nonequilibrium effects could drive the thiol-terminated silanes far away from equilibrium even at low biases of around 0.2 V. Further analysis suggests that these nonequilibrium effects could generally exist in nanoscale devices in which there are conducting channels mainly residing at the source contact and close to the bias window. These findings significantly broaden our fundamental understanding of electron transport at the nanoscale. |
