Giant anisotropy of Zeeman splitting of quantum confined acceptors in Si/Ge

TL;DR

This paper investigates the highly anisotropic Zeeman splitting of acceptor levels in Si/Ge quantum wells, revealing a strong dependence on magnetic field orientation due to strain and quantum confinement effects.

Contribution

It demonstrates the giant anisotropy of Zeeman splitting in Si/Ge quantum wells caused by strain-induced light hole-heavy hole splitting, using resonant tunneling spectroscopy.

Findings

Linear Zeeman splitting in perpendicular magnetic fields

Suppressed Zeeman splitting in in-plane magnetic fields

Strain and quantum confinement cause large light hole-heavy hole splitting

Abstract

Shallow acceptor levels in Si/Ge/Si quantum well heterostructures are characterized by resonant tunneling spectroscopy in the presence of high magnetic fields. In a perpendicular magnetic field we observe a linear Zeeman splitting of the acceptor levels. In an in-plane field, on the other hand, the Zeeman splitting is strongly suppressed. This anisotropic Zeeman splitting is shown to be a consequence of the huge light hole-heavy hole splitting caused by a large biaxial strain and a strong quantum confinement in the Ge quantum well.