Electronic and transport properties of anisotropic semiconductor quantum wires

TL;DR

This paper theoretically investigates how anisotropic effective masses and orientations affect the electronic and transport properties of 2D semiconductor quantum wires, revealing orientation-dependent energy levels and wavepacket dynamics.

Contribution

It provides analytical calculations of energy levels and transport properties in anisotropic quantum wires, including effects of magnetic fields and wavepacket evolution, which are novel insights.

Findings

Energy levels depend strongly on wire orientation and anisotropy axis.

Quantum Hall edge states are affected by edge orientation in magnetic fields.

Wavepacket velocity oscillations are damped and orientation-dependent.

Abstract

Within the effective-mass approximation, we theoretically investigated the electronic and transport properties of 2D semiconductor quantum wires (QWs) with anisotropic effective masses and different orientations with respect to the anisotropic axis. The energy levels in the absence and presence of an external magnetic field are analytically calculated, showing: (i) a strong dependence on the spacing of energy levels related to the alignment QW angle and the anisotropy axis; and (ii) for non-null magnetic field, the quantum Hall edge states are significantly affected by the edge orientation. Moreover, by means of the split-operator technique, we analyzed the time evolution of wavepackets in straight and V-shaped anisotropic QWs and compared the transmission probabilities with those of isotropic systems. In the anisotropic case we found damped oscillations in the average values of velocity in both x and y directions for a symmetric Gaussian wavepacket propagating along a straight wide QW, with the oscillation being more evident as the non-collinearity between the group velocity and momentum vectors increases.