Attenuation and amplification of the transient current in nanojunctions with time-varying gate potentials

Issue Date

4-2017

Abstract

We study charge transport in a source-channel-drain system with a time-varying applied gate potential acting on the channel. We calculate both the current flowing from the source into channel and out of the channel into the drain. The current is expressed in terms of nonequilibrium Green's functions. These nonequilibrium Green's functions can be determined from the steady-state Green's functions and the equilibrium Green's functions of the free leads. We find that the application of the gate potential can induce current to flow even when there is no source-drain bias potential. However, the direction of the current from the source and the current to the drain are opposite, thereby resulting in no net current flowing within the channel. When a source-drain bias potential is present, the net current flowing to the source and drain can either be attenuated or amplified depending on the sign of the applied gate potential. We also find that the response of the system to a dynamically changing gate potential is not instantaneous, i.e., a relaxation time has to pass before the current settles into a steady value. In particular, when the gate potential is in the form of a step function, the current first overshoots to a maximum value, oscillates and then settles down to a steady-state value.

Source or Periodical Title

International Journal of Modern Physics B

ISSN

0217-9792

Volume

21

Issue

18

Page

1-15

Document Type

Article

Physical Description

illustrations, figures, graphs, tables,

Language

English

Subject

Nanodevices; Nonequilibrium Green's functions; Time-dependent quantum transport

Identifier

DOI:10.1142/S0217979217501053

Digital Copy

yes

En – AGROVOC descriptors

Nanodevices; Nonequilibrium Green's functions; Time-dependent quantum transport

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