X-ray crystallographic investigation of ZnS:Ag, Cu, Mg single crystals

Splitting of the profiles of diffraction lines from the [110] planes of ZnS:Ag, Cu, Mg single crystals into two, and sometimes three, peaks has been observed. The relative intensity of the peaks is compared with the volume fraction, obtained from optical excitonic spectra, of interlayers of a hexagonal phase in the samples. Fiz. Tverd. Tela (St. Petersburg) 39, 49–51 (January 1997)     

Study of the Phase Transition in Hg<Subscript>2</Subscript>Cl<Subscript>2</Subscript> Crystals Using Anomalous X-Ray Transmission

The small-angle X-ray scattering in calomel (univalent mercury chloride Hg₂Cl₂) single crystals at low temperatures has been investigated. Data on the size of superstructural ferroelectric domains have been obtained for the first time. Lang measurements with anomalous X-ray transmission have made it possible to trace the temperature dynamics of crystal lattice of the high-temperature D_4h phase of Hg₂Cl₂ from 300 K to the Curie temperature (186 K) and the formation of ferroelastic domains in the temperature range of 186–100 K. The lowering of paraphase symmetry in the closest vicinity of the phase transition temperature is indicative of tricritical point transition.     

Use of the variational principle with the aim of determining oscillations in the extended X-ray absorption fine structure

A method of determining the smooth and oscillating components of extended X-ray absorption fine structure spectra is developed. The form of a functional that is minimized by the desired smooth function is suggested, and a series of EXAFS spectra is analyzed. A way of solution optimization is proposed. The results of applying the method to experimental spectra are reported.     

Small-angle X-ray studies of the GaAs0.7Se0.3 solid solution at energies close to as and Se absorption edges

The possibility of a simultaneous use of X-ray diffraction and X-ray absorption techniques in order to characterize the sizes, shapes, and chemical composition of grains in a sample (the solution of the extended uncertainty problem due to the Babinet principle) is shown. A sample of the GaAs_0.7Se_0.3/GaAs solid solution is investigated on the developed laboratory device for a simultaneous performance of X-ray diffraction and X-ray absorption experiments. It is shown that the GaAs_0.7Se_0.3 sample decomposes into separate GaAs and GaSe domains forming a mosaic structure. The sizes of GaAs and GaSe domains are estimated. Components with a linear geometry are sometimes revealed in the composition of GaSe grains.     

X-ray studies of the domain formation in rocks under blasting

Quartz plates placed in concrete are used to model the rock blasting procedure. Quartz fragments resulted from blasting are studied by small-angle X-ray scattering. Obtained grains in the quartz fragments are approximately 200–220 nm in size. The samples are discovered to contain low-dimensional (linear) components; the further the sample is from the explosion center, the coarser the grains are in it. Superlattice parameters of the studied fragments are estimated. It is suggested that domain boundaries in the sample quartz fragments are linear objects, such as dislocation walls.     

Calculation of field in plane-layered microelectronic materials

A modification of the method for calculation of horizontal and vertical components of monochromatic field that is generated in plane-layered medium by horizontal current flow and described using wave equation is proposed for problems of microelectronics. The proposed solution is based on the verified method of equivalent propagation constant that makes it possible to substantially reduce the amount of calculations in comparison with alternative methods based on rigorous dynamic approach. The analysis illustrates the application of the method at relatively small distances.     

Features of the structure and defect states in hydrogenated polymorphous silicon films

The structural and electronic properties of thin hydrogenated polymorphous silicon films obtained by plasma-enhanced chemical vapor deposition from hydrogen (H₂) and monosilane (SiH₄) gas mixture have been studied by means of transmission electron microscopy, electron paramagnetic resonance (EPR) spectroscopy, and Raman spectroscopy. It has been established that the studied films consist of the amorphous phase containing silicon nanocrystalline inclusions with the average size on the order of 4–5 nm and the volume fraction of 10%. A signal was observed in the hydrogenated polymorphous silicon films during the EPR investigation that is attributed to the electrons trapped in the conduction band tail of microcrystalline silicon. It has been shown that the introduction of a small fraction of nanocrystals into the amorphous silicon films nonadditively changes the electronic properties of the material.     

Mutual synchronization of two coupled self-oscillators based on GaAs/AlGaAs superlattices

The interaction of self-oscillators based on 30-period weakly coupled GaAs/AlGaAs superlattices is studied. The action of one self-oscillator on the other was observed for a constant bias voltage in the absence of generation of self-sustained oscillations in one of the oscillators. It is shown that induced oscillations in a forced oscillator appear due to excitation of oscillations in the system of coupled oscillators forming the electric-field domain wall at the frequency of one of the higher harmonics of a forcing oscillation.