Suppression of secondary phase formation in Fe implanted ZnO single crystals

TL;DR

This study demonstrates methods to prevent secondary phase formation in Fe-implanted ZnO single crystals, significantly reducing unwanted magnetic clusters and promoting uniform magnetic properties.

Contribution

The paper introduces annealing procedures that suppress secondary phase formation in Fe-doped ZnO, enhancing the material's magnetic uniformity and potential for spintronic applications.

Findings

High-temperature annealing suppresses Fe nanoparticle formation.

Preannealed samples show 20 times lower residual magnetization.

Magnetism is due to isolated Fe ions, not clusters.

Abstract

Unwanted secondary phases are one of the major problems in diluted magnetic semiconductor creation. Here, the authors show possibilities to avoid such phases in Fe implanted and postannealed ZnO(0001) single crystals. While -Fe nanoparticles are formed after such doping in as-polished crystals, high temperature (1273 K) annealing in O2 or high vacuum before implantation suppresses these phases. Thus, the residual saturation magnetization in the preannealed ZnO single crystals is about 20 times lower than for the as-polished ones and assigned to indirect coupling between isolated Fe ions rather than to clusters.