Postprint version. Published in Journal of Crysal Growth, Volume 269, Issue 2-4, September 1, 2004, pages 298-303.
At the time of publication, author N. Keim was not yet affiliated with Cal Poly.
The definitive version is available at https://doi.org/10.1016/j.jcrysgro.2004.05.091.
Relaxed InyGa1−yAs epilayers grown on (0 0 1) GaAs are known to exhibit a cross-hatched surface with ridges running along the [1 1 0] and directions. We find that Ga1−xMnxAs epilayers grown on such buffer layers can have as-grown Curie temperatures (TC) that are higher than the as-grown 110 K value typical of Ga1−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 Ga1−xMnxAs /InyGa1−yAs heterostructures is smaller than that in as-grown Ga1−xMnxAs/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.