Nanoscale capacitance: A quantum tight-binding model

作者：Zhai, Feng; Wu, Jian; Li, Yang; Lu, Jun-Qiang^*

来源：Physics Letters, Section A: General, Atomic and Solid State Physics , 2017, 381(1): 44-47.

DOI：10.1016/j.physleta.2016.10.038

• Nanoscale capacitance
• Nano-gap
• Tight-binding model
• Carbon nanotube
• Quantum capacitance

Landauer-Buttiker formalism with the assumption of semi-infinite electrodes as reservoirs has been the standard approach in modeling steady electron transport through nanoscale devices. However, modeling dynamic electron transport properties, especially nanoscale capacitance, is a challenging problem because of dynamic contributions from electrodes, which is neglectable in modeling macroscopic capacitance and mesoscopic conductance. We implement a self-consistent quantum tight-binding model to calculate capacitance of a nano-gap system consisting of an electrode capacitance C ' and an effective capacitance C-d of the middle device. From the calculations on a nano-gap made of carbon nanotube with a buckyball therein, we show that when the electrode length increases, the electrode capacitance C ' moves up while the effective capacitance Cd converges to a value which is much smaller than the electrode capacitance C '. Our results reveal the importance of electrodes in modeling nanoscale ac circuits, and indicate that the concepts of semi-infinite electrodes and reservoirs well-accepted in the steady electron transport theory may be not applicable in modeling dynamic transport properties.

• 出版日期2017-1-5
• 单位清华大学; 浙江师范大学