Capping-induced suppression of annealing effects on Ga1−xMnxAs epilayers

We have studied the effects of capping ferromagnetic Ga1−xMnxAs epilayers with a thin layer of undoped GaAs, and we find that even a few monolayers of GaAs have a significant effect on the ferromagnetic properties. In particular, the presence of a capping layer only 10 monolayers thick completely suppresses the enhancement of the ferromagnetism associated with low temperature annealing. This result, which demonstrates that the surface of a Ga1−xMnxAs epilayer strongly affects the defect structure, has important implications for the incorporation of Ga1−xMnxAs into device heterostructures.

我们研究了用一层未掺杂的砷化镓（GaAs）薄层覆盖铁磁性Ga₁₋ₓMnₓAs外延层的效应，并且发现即使是几个单原子层的砷化镓对铁磁特性也有显著影响。特别是，仅10个单原子层厚的覆盖层的存在完全抑制了与低温退火相关的铁磁性增强。这一结果表明Ga₁₋ₓMnₓAs外延层的表面强烈影响缺陷结构，对于将Ga₁₋ₓMnₓAs集成到器件异质结构中具有重要意义。