Diffusion and Defects in Elementary and Compound Semiconductors
Curie temperature and carrier concentration gradients in epitaxy-grown
Ga1-xMnxAs layers
We investigated the electronic and magnetic properties of ferromagnetic
Ga1-xMnxAs layers, which have been fabricated by low-temperature molecular-beam
epitaxy. Superconducting quantum interference device measurements reveal a decrease of the Curie temperature
from the surface to the Ga1-xMnxAs/GaAs interface. While high-resolution
x-ray diffraction clearly shows a homogeneous Mn distribution, a pronounced decrease of the
carrier concentration from the surface towards the Ga1-xMnxAs/GaAs interface has
been found by Raman spectroscopy as well as electrochemical capacitance-voltage profiling. The gradient in
Curie temperature seems to be a general feature of Ga1-xMnxAs layers grown at low
temperature. Posssible explanations are discussed in our publication.
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