Thin (50-90 m) non-doped and doped (by Al atoms) Mg2Sn0.6Si0.4 and Mg2Sn0.4Si0.6films with roughness of 1.9-3.7 nm have been grown by multiple deposition and single annealing at 150 °C of multilayers formed by repetition deposition of three-layers (Si-Sn-Mg) on Si(111) p-type wafers with 45 Ω-cm resistivity. Transmission electron microscopy has shown that the first forming layer is an epitaxial layer of hex-Mg2Sn(300) on Si(111) substrate with thickness not more than 5-7 nm. Epitaxial relationships:hex-Mg2Sn(300)|| Si(111), hex-Mg2Sn|| Si[-112] and hex-Mg2Sn||Si have been found for the epitaxial layer. But inclusions of cub-Mg2Si were also observed inside hex-Mg2Sn layer. It was found that the remaining part of the film thickness is in amorphous state and has a layered distribution of major elements: Mg, Sn and Mg without exact chemical composition. It was established by optical spectroscopy data that both type films are semiconductor with undispersed region lower 0.18 eV with no= 3.59 ± 0.01, but only two direct interband transitions with energies 0.75-0.76 eV and 1.2 eV have been determined. The last interband transition has been confirmed by photoreflectance data at room temperature. Fourier transmittance spectroscopy and Raman spectroscopy data have established the formation of stannide, silicide and ternary compositions.
Morphology, optical properties, crystal and electronic structure of monocrystal silicon after plasma processing,
depending on initial voltage of magnetoplasma compressor (MPC), have been studied. It was shown that periodic surface
structures are formed on silicon only in the short range ofinitial MPC voltages (2.8-3.2 kV), but at higher initial voltages
(3.4-3.6 kV) the formation of "crater" and carrying out of the part of material on its periphery till the moment of
crystallization is observed without the formation of surface structures. The decrease of the silicon lattice constant has
been observed after plasma processing at all initial voltages that correlates with the decrease of band-gap energy by data
of optical spectroscopy. Changes in crystal lattice and electronic structure of silicon modified by compression plasma
flow have confirmed by red shift of 4.5 eV peak in reflectance spectra and decrease of its amplitude.
A technology of solid-phase growth of Mg2Si thin films from Mg and Si layers on a pre-fabricated template layer of Mg2Si islands on Si (111) has been developed. The optimum temperature (T=550° C) for growth of epitaxial Mg2Si films on Si (111) has been found. It has been shown from optical spectroscopy data that Mg2Si epitaxial film has a direct fundamental transition with the energy of 0.75-0.76 eV with small combined density of states. It represents transition of small number of valence electrons into Mg-Si bonding states in the conductance band. The strong absorption range (1.9-6.2 eV) corresponds to transitions from bonding to anti-bonding states.
The technology of solid-phase growth of nanosize islands of magnesium suicide on Si (111) 7x7 with narrow distributions of lateral size and height (60 - 80 and 5 - 7 nanometers, respectively) and density of up to 2x 109 sm-2 is proposed. A 20-50 nm thick Si layer has been grown upon these islands. Basing on the data of AES, EELS, AFM and JR spectroscopy, a conclusion is made that the Mg2Si islands remain in depth of the Si layer. The suggestion is made that sizes, density and crystal structure of the buried magnesium suicide clusters preserves. It is shown, that the system of three as-grown layers of buried clusters has smoother surface than the one layer system. The contribution of the Mg2Si clusters into the dielectric function is observed at the energy 0.8-1.2 eV, it is maximal if the clusters are localized on the silicon surface. It is shown, that with increase of the number of Mg2Si cluster layers their contribution increases into the effective number of electrons per a unit cell and effective dielectric function of the sample.
Solid phase multilayer growth technique of magnesium silicide (Mg2Si) films with preliminary formation of templates, allowing to growth the thick (60-100 nm) Mg2Si film, has offered. Optical function data have shown, that thick (60-80 nm) Mg2Si films are the narrow band semiconductor with optical band gap of Egopt = 0.75 eV and two absorption regions with the small state density at 0.75-2.1 eV and large state density at 2.3-6.2 eV on Mg2Si cell, but in the second range about 3.0 electrons on Mg2Si cell participate in formation of electronic structure. The integrated spectra of the dielectric function of Mg2Si have been decomposed into the contributions from four non-interacting harmonic oscillators and the parameters of these oscillators were evaluated. It was established that the third harmonic oscillator (Ep=2.50 eV) with large oscillator strength introduces the main contribution into the dielectric function. The researches of electrical properties of thick magnesium silicide films on silicon also have shown, that they are narrow band semiconductors of p-type conductivity with energy band gap (Egel=0.77 eV), in which the high mobility holes with high rate of their scattering was observed at temperature increase (μ~T-4.0). On temperature dependencies of carrier concentration two activation regions, connected to a generation of carriers through fundamental transition (0.77 eV) and second interband transition with energy 2.78 eV, have been found.