A possible route to grow a (Mn:Si(1-x)Gex)-based diluted magnetic semiconductor

TL;DR

This study uses ab initio calculations to explore how manganese impurities behave in silicon-germanium alloys, revealing conditions that favor the formation of magnetic semiconductors.

Contribution

It demonstrates that chemical effects, rather than volume effects, influence Mn site preference in SiGe alloys, suggesting a pathway to grow Mn-doped Si-based magnetic semiconductors.

Findings

Substitutional Mn becomes more stable in Ge-rich regions for x > 0.16.

Volume effects are not the main factor in Mn site preference.

Chemical effects significantly influence Mn impurity behavior.

Abstract

We systematically investigate, using ab initio density-functional theory calculations, the properties of interstitial and substitutional Mn in both Si and Ge, as well as in the Si(1-x)Gex alloy. We show that volume effects are not the main reason Mn prefers to be a subsitutional impurity in pure Ge, and chemical effects, therefore, play an important role. Using realistic models of Si(1-x)Gex, we show that for x approximately greater than 0.16 substitutional Mn in Ge-rich neighborhoods become more stable than interstitial Mn, which may allow the growth of Si-based diluted magnetic semiconductors.