Enhanced annealing effect in an oxygen atmosphere on GaMnAs

TL;DR

This study investigates how annealing GaMnAs in oxygen atmospheres affects its resistivity and magnetic properties, revealing oxygen's role in passivating Mn interstitials and optimizing thin film quality.

Contribution

It demonstrates that oxygen atmosphere enhances passivation of Mn interstitials in GaMnAs, providing a new method to improve film properties during annealing.

Findings

Resistivity drops during oxygen annealing due to Mn interstitial passivation.

Oxygen limits oxidation to the surface, preventing bulk damage.

Oxygen-free annealing increases resistivity and reduces active Mn atoms.

Abstract

We report on in-situ resistivity measurements on GaMnAs during post-growth annealing in different atmospheres. A drop in the resistivity is observed when the GaMnAs is exposed to oxygen, which indicates that the passivation of Mn interstitials (Mn_I) at the free surface occurs through oxidation. The presence of oxygen can therefore be an important annealing condition for the optimization of GaMnAs thin films, all the more since the oxidation appears to be limited to the sample surface. Annealing in an oxygen-free atmosphere leads to an increase in the resistivity indicating a second annealing mechanism besides the out-diffusion of Mn_I. According to our magnetization and Hall effect data, this mechanism reduces the amount of magnetically and electrically active Mn atoms.