Voids and Mn-rich inclusions in a (Ga,Mn)As ferromagnetic semiconductor investigated by transmission electron microscopy

TL;DR

This study uses advanced transmission electron microscopy to analyze voids and Mn-rich nanocrystals in annealed (Ga,Mn)As, revealing their structure, lattice deviations, and effects on magnetic properties.

Contribution

It provides detailed characterization of voids and nanocrystals in (Ga,Mn)As, including their lattice deviations and growth behavior during annealing.

Findings

Voids are adjacent to cubic and hexagonal Mn-rich nanocrystals.

Nanocrystals show deviations in lattice parameters from bulk MnAs.

Annealing at 903 K influences the magnetic transition temperature due to nanocrystal formation.

Abstract

Voids adjacent to both cubic (ZnS-type) and hexagonal (NiAs-type) Mn-rich nanocrystals are characterized using aberration-corrected transmission electron microscopy in annealed Ga0.995Mn0.005As magnetic semiconductor specimen grown by molecular beam epitaxy. Nano-beam electron diffraction measurements suggest that the nanocrystals exhibit deviations in lattice parameter from that of bulk MnAs. In situ annealing inside the electron microscope is used to study the nucleation, coalescence, and grain growth of individual nanocrystals. After annealing at 903 K, the magnetic transition temperature of the specimen likely to be dominated by the presence of cubic ferromagnetic nanocrystals.