StatusThe thesis was presented on the 6 May, 2015
Approved by NCAA on the 7 July, 2015
Abstract– 0.96 Mb / in romanian
– 0.88 Mb / in russian
2.76 Mb /
Key words: band structure, antiferromagnetic, impurity, conductivity, luminescence, thin layers, heterojunctions, the spectral sensitivity.
The main purpose of the thesis is a comprehensive investigationof the electrical, optical and luminescent properties of crystals and thin layers of Cd1-xMnxTe, the definition of the band structure, electrical and photoelectric parameters depending on the composition and type of impurities, determination of the mechanisms of current and photovoltaic effect in heterojunctions nCdS- pCd1-xMnxTe.
Scientific novelty and originalityof the thesis is that the first time has been studied in detail the band structure of a series of solid solution of Cd1-xMnxTe (0≤x≤0,5), the dependence of the spin-orbit splitting of the valence band on the composition and temperature. The mechanical properties of crystals Cd1-xMnxTe, and magnetic properties depending on the composition in the temperature range of 1,79 ÷ 400 K were first studied. The effect of doping with various impurities (Cd, Te, Cu) on the electrical, optical and luminescent properties of the crystals Cd1-xMnxTe was investigated. The heterojunctions nCdS-pCd1-xMnxTe were first obtained and their electrical and photoelectric properties were studied.
The main scientific problem resolved by this thesis is:control over energy band structure of crystals Cd1-xMnxTe, changing the concentration of Mn; control over the carrier concentration and conductivity type crystals Cd1-xMnxTe, adding various impurities; receiving heterojunctions with high photosensitivity which may be used to manufacture solar cells with an efficiency of 11 ÷ 12%.
Theoretical significance and practical value of the work. The results of these studies provide an opportunity to explain the features of the photoelectric properties of semiconductors Cd1-xMnxTe and structures of various types based on them and relations with the applied magnetic fields. The semiconductor structure of Cd1-xMnxTe is convenient because of it allows to control over, is necessary, the band gap, refractive index, absorption coefficient et al., varying the concentration of Mn and may change under the influence of a magnetic field. Manganese atoms occupy lattice sites, which leads to the formation of an "ideal" solid solution, and that determines ability to use Cd1-xMnxTe for creating a barrier layer in two-dimensional semiconductor structures, optical modulators, and various optoelectronic devices "spintronics."