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

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 semiinsulating (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. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2491

Band-structure analysis in (Ga,Mn)As epitaxial layers

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 valence-band 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 - 700nm and 230 – 300nm) (Ga,Mn)As layers with Mn content in the range from 0.001% to 6% and, as a reference, undoped GaAs layer, grown by LT-MBE on semiinsulating (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 valenceband holes. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2063

Photoreflectance Study of the Fundamental Optical Properties of (Ga,Mn)As Epitaxial Films

Fundamental optical properties of thin films of (Ga,Mn)As diluted ferromagnetic semiconductor with a low (1%) and high (6%) Mn content and of a reference GaAs film, grown by low-temperature molecular-beam epitaxy, have been investigated by photoreflectance (PR) spectroscopy. In addition, the films were subjected to complementary characterization by means of superconducting quantum interference device (SQUID) magnetometry, Raman spectroscopy, and high resolution X-ray diffractometry. Thorough full-line-shape analysis of the PR spectra, which enabled determination of the E0 electronic transition in (Ga,Mn)As, revealed significant differences between the energy band structures in vicinity of the {\Gamma} point of the Brillouin zone for the two (Ga,Mn)As films. In view of the obtained experimental results the evolution of the valence band structure in (Ga,Mn)As with increasing Mn content is discussed, pointing to a merging the Mn-related impurity band with the host GaAs valence band for high Mn content.Comment: 21 pages, 6 figure

Ferromagnetism and Electronic Structure of (Ga,Mn)As:Bi and (Ga,Mn)As Epitaxial Layers

The photoreflectance (PR) spectroscopy was applied to study the band-structure in GaAs:Bi, (Ga,Mn)As and (Ga,Mn)As:Bi layers with the 4% of Mn and 1 % of Bi content and, as a reference, undoped GaAs layer. All films were grown by low temperature (LT) MBE on semi-insulating (001) GaAs substrates. Photoreflec-tance studies were supported by Raman spectroscopy and high resolution X-ray diffractometry (XRD) measurements. Magnetic properties of the films were characterized with a superconducting quantum in-terference device (SQUID) magnetometer. Our findings were interpreted in terms of the model, which as-sumes that the mobile holes residing in the valence band of GaAs and the Fermi level position determined by the concentration of valence-band holes. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3533