Relaxed InyGa1-yAs epilayers grown on (001) GaAs are known to exhibit a cross-hatched surface with ridges running along the  and [11̄0] directions. We find that Ga1-xMnxAs epilayers grown on such buffer layers can have as-grown Curie temperatures (T C) that are higher than the as-grown 110K value typical of Ga 1-xMnxAs/GaAs heterostructures. Further, low-temperature annealing leads to only modest additional increases in TC, contrasting with the behavior in Ga1-xMnxAs/GaAs where TC typically increases significantly upon annealing. Our observations suggest that the initial concentration of Mn interstitials in as-grown Ga 1-xMnxAs /InyGa1-yAs heterostructures is smaller than that in as-grown Ga1-xMn xAs/GaAs heterostructures. We propose that strain-dependent diffusion may drive Mn interstitials from the bulk of the growing crystal to more benign locations on the ridged surface, providing a possible route towards defect-engineering in these materials.
- A3. Molecular beam epitaxy
- B1. GaMnAs
- B2. Ferromagnetic semiconductors
ASJC Scopus subject areas
- Condensed Matter Physics