Analysis of the Band-Structure in (Ga, Mn)As Epitaxial Layers by Optical Methods

Authors O. Yastrubchak
Affiliations Institute of Physics, Maria Curie-Skłodowska University, Place Marii Curie-Skłodowskiej 1, 20-031 Lublin, Poland
Issue Volume 4, Year 2012, Number 1
Dates Received 31 October 2011; revised manuscript received 28 February 2012; published online 14 March 2012
Citation O. Yastrubchak, J. Nano-Electron. Phys. 4 No 1, 01016 (2012)
PACS Number(s) 1.20.Mq, 83.85.Ei
Keywords Spintronics (2) , Diluted ferromagnetic semiconductor, Photoreflectance (PR) spectroscopy, Fermi level (2) , (Ga (3) ,  Mn)As.
Annotation The ternary III-V semiconductor (Ga, Mn)As has recently drawn a lot of attention as the model diluted ferromagnetic semiconductor, combining semiconducting properties with magnetism. (Ga, Mn)As layers are usually gown by the low-temperature molecular-beam epitaxy (LT-MBE) technique. Below a magnetic transition temperature, TC, substitutional Mn2+ ions are ferromagnetically ordered owing to interaction with spin-polarized holes. However, the character of electronic states near the Fermi energy and the electronic structure in ferromagnetic (Ga, Mn)As are still a matter of controversy. The photoreflectance (PR) spectroscopy was applied to study the band-structure evolution in (Ga, Mn)As layers with increasing Mn content. We have investigated thick (800-700 nm and 230-300 nm) (Ga, Mn)As layers with Mn content in the wide range from 0.001 % to 6 % and, as a reference, undoped GaAs layer, grown by LT-MBE on semi-insulating (001) GaAs substrates. Our findings were interpreted in terms of the model, which assumes that the mobile holes residing in the valence band of ferromagnetic (Ga, Mn)As and the Fermi level position determined by the concentration of valence-band holes.

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