Mn Solid Solutions in Self-Assembled Ge/Si (001) Quantum Dot Heterostructures

TL;DR

This study investigates Mn-doped Ge quantum dots grown on Si (001), revealing their structural and magnetic properties, including dilute Mn solutions and silicide precipitates, but no robust room-temperature ferromagnetism.

Contribution

It demonstrates the formation of Mn solid solutions and silicide precipitates in Ge quantum dots on Si, providing insights into their structural and magnetic characteristics.

Findings

Mn forms a dilute solid solution in Ge quantum dots.

Silicide precipitates are found beneath some Ge superdomes.

No robust room-temperature ferromagnetism observed.

Abstract

Heteroepitaxial Ge0.98Mn0.02 quantum dots on Si (001) were grown by molecular beam epitaxy. The standard Ge wetting layer-hut-dome-superdome sequence was observed, with no indicators of second phase formation in the surface morphology. We show that Mn forms a dilute solid solution in the Ge quantum dot layer, and a significant fraction of the Mn partitions into a sparse array of buried, Mn-enriched silicide precipitates directly underneath a fraction of the Ge superdomes. The magnetic response from the ultra-thin film indicates the absence of robust room temperature ferromagnetism, perhaps due to anomalous intermixing of Si into the Ge quantum dots.