Possibility of coherent electron transport in a nanoscale circuit

TL;DR

This paper explores the potential for coherent electron transport in nanoscale circuits, proposing methods to identify and analyze sharply-defined coherent modes using analytical solutions of the Schrödinger equation.

Contribution

It introduces algorithms to determine parameters and current distributions for coherent modes in nanoscale circuits, emphasizing the use of single-crystal wires and tunneling junctions.

Findings

Existence of sharply-defined coherent modes in nanoscale circuits

Algorithms for parameter determination of these modes

Analytical solutions for wavefunction and current distribution

Abstract

Others have solved the Schr\"odinger equation to estimate the tunneling current between two electrodes at specified potentials, or the transmission through a potential barrier, assuming that an incident wave causes one reflected wave and one transmitted wave. However, this may not be appropriate in some nanoscale circuits because the electron mean-free path may be as long as 68 nm in metals. Thus, the wavefunction may be coherent throughout the metal components in a circuit if the interaction of the electrons with the surface of conductors and grain boundaries, which reduces the mean-free path, is reduced. We consider the use of single-crystal wires, and include a tunneling junction to focus and collimate the electrons near the axis, to further reduce their interaction with the surface of the wire. Our simulations suggest that, in addition to the incoherent phenomena, there are extremely sharply-defined coherent modes in nanoscale circuits. Algorithms are presented with examples to determine the sets of the parameters for these modes. Other algorithms are presented to determine the normalized coefficients in the wavefunction and the distribution of current in the circuits. This is done using only algebra with calculus for analytical solutions of the Schr\"odinger equation.