Electron microscopy and diffraction study of high-temperature diamond-like Si-based ferromagnetic with self-organized super-lattice distribution of Mn impurity

TL;DR

This study uses advanced electron microscopy and diffraction techniques to reveal the detailed structure and self-organized super-lattice distribution of Mn impurities in high-temperature Si:Mn ferromagnetic semiconductors.

Contribution

It provides new high-resolution structural data showing self-organized super-lattice structures and the atomic arrangement of Mn in epitaxial Si:Mn films, advancing understanding of their magnetic properties.

Findings

Si:Mn can be represented as Si2+xMn1-x with a diamond-like structure.

Self-organized super-lattice structures with triple-periodicity are observed.

Mn atoms form one-atom-thick strips within the (110) layers.

Abstract

New structure data for the high-temperature diluted magnetic semiconductor Si:Mn, synthesized by laser method are presented. The higher resolution transmission electron microscopy and diffraction was applied in two crystal directions of epitaxial layers of DMS Si:Mn with elimination of the contribution from GaAs substrate and interface. It is established, that the DMS Si:Mn can be represent as compound with variable composition Si2+xMn1-x (0 <x <1), single-phase diamond like structure, high crystal perfection and the self-organized formation of the super-lattice structures with the period equal to triple the distance between the nearest (110) atomic layers and interval between (110) layers which are doped by Mn atoms and orientated along the direction of Si:Mn film growth. The Si with 15 percent of Mn (or Si2.5Mn0.5) films consist of blocks with the 15-50 nm sizes and with mutually perpendicular orientations of the super-lattice modulations. Atoms of manganese in the (110) layers, doped by these impurity, settle down in the form of strips of an one-atom thickness. These manganese strips in the given (110) layer alternate occupy about half of area of the layer (110) in the full consent with the spectral X-ray analysis and ferromagnetic resonance data.