Quantum confinement effects in Si/Ge heterostructures with spatially ordered arrays of self-assembled quantum dots

TL;DR

This paper investigates quantum confinement in Si/Ge heterostructures with ordered quantum dots using magnetotunneling spectroscopy, revealing resonant tunneling behavior and quantifying confinement potential strengths.

Contribution

It provides experimental evidence of three-dimensional hole confinement in Ge quantum dots and introduces a method to quantify confinement potential in such heterostructures.

Findings

Resonant tunneling of heavy-holes observed near zero bias.

Step-like current-voltage behavior indicating quantum dot confinement.

Quantified confinement potential strength assuming parabolic confinement.

Abstract

Magnetotunneling spectroscopy was employed to probe the confinement in vertical Si/Ge double-barrier resonant tunneling diodes with regularly distributed Ge quantum dots. Their current-voltage characteristics reveal a step-like behavior in the vicinity of zero bias, indicating resonant tunneling of heavy-holes via three-dimensionally confined unoccupied hole states in Ge quantum dots. Assuming parabolic confinement we extract the strength of the confinement potential of quantum dots.