Structural Transformation of “Silica+Zn” Nanocomposite after Annealing in Oxidizing Atmosphere

Semiconductors - It has been found that “hot” high-fluence Zn+ implantation leads to the formation of the extended layer with zinc-based nanoclusters of size up to 10 nm in SiO2 film....     

Electrical Properties of <Emphasis Type="Italic">p</Emphasis>-NiO/<Emphasis Type="Italic">n</Emphasis>-Si Heterostructures Based on Nanostructured Silicon

Silicon nanowires are formed on n-Si substrates by chemical etching. p-NiO/n-Si heterostructures are fabricated by reactive magnetron sputtering. The energy diagram of anisotype p-NiO/n-Si heterostructures is constructed according to the Anderson model. The current–voltage and capacitance–voltage characteristics are measured and analyzed. The main current-transport mechanisms through the p-NiO/n-Si heterojunction under forward and reverse biases are established.     

Deformation Anisotropy of <Emphasis Type="Italic">Y</Emphasis> + 128°-Cut Single Crystalline Bidomain Wafers of Lithium Niobate

Bidomain single crystals of lithium niobate (LiNbO₃) and lithium tantalate (LiTaO₃) are promising materials for use as actuators, mechanoelectrical transducers, and sensors capable of working in a wide temperature range. One need to take into account the anisotropy of the properties of the crystalline material when such devices are designed. In this study we investigated deformations of bidomain round shaped Y + 128°-cut wafers of lithium niobate in an external electric field. The dependences of the piezoelectric coefficients on the rotation angles were calculated for lithium niobate and lithium tantalate and plotted for the crystal cuts which are used for the formation of a bidomain ferroelectric structure. In the experiment, we utilized an external heating method and long-time annealing with the lithium out-diffusion method in order to create round bidomain lithium niobate wafers. Optical microscopy was used to obtain the dependences of the bidomain crystals’ movements on the rotation angle with central fastening and the application of an external electric field. We also modelled the shape of the deformed bidomain wafer with the suggestion that the edge movement depends on the radial distance to the fastening point quadratically. In conclusion, we revealed that the bidomain Y + 128°-cut lithium niobate wafer exhibits a saddle-like deformation when a DC electric field is applied.     

Quantum dots grown in the InSb/GaSb system by liquid-phase epitaxy

The first results of the liquid-phase epitaxial growth of quantum dots in the InSb/GaSb system and atomic-force microscopy data on the structural characteristics of the quantum dots are reported. It is shown that the surface density, shape, and size of nanoislands depend on the deposition temperature and the chemical properties of the matrix surface. Arrays of InSb quantum dots on GaSb (001) substrates are produced in the temperature range T = 450–465°C. The average dimensions of the quantum dots correspond to a height of h = 3 nm and a base dimension of D = 30 nm; the surface density is 3 × 10⁹ cm^–2.     

Small-angle neutron scattering investigation of the substructure of nickel irradiated with fast neutrons

The method of small-angle neutron scattering has been used to investigate the samples of pure nickel before and after irradiation with fast neutron fluences of Φ = 10¹⁸, 10¹⁹, and 10²⁰ cm^?2 (E _n ≥ 0.1 MeV). It has been found that the substructure of the samples consists of vacancy clusters with two characteristic sizes of 2.5–4 and ～7 nm. The sizes of precipitates weakly depend on fast neutron fluence. The magnitude of their density is on the order of 10²² and 10¹⁹ m^?3, respectively, and increases by three to ten times as the fluence grows.     

X-ray diffraction determination of the composition of In<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Ga<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>Sb solid solution

A procedure to determine the composition of In _x Ga_{1 − x} Sb solid solution by X-ray diffraction is described. In order to calculate the indium content in a solid solution, an expression is proposed which relates the cell size of an undeformed layer with the dimensions of a tetragonally distorted unit cell of the layer under strain caused by a discrepancy in the dimensions of the layer and substrate lattices. The procedure yields results that well agree with measurements of the solid solution composition in a layer by energy dispersive spectroscopic control performed using an electron microscope.     

Specific features of electroluminescence in heterostructures with InSb quantum dots in an InAs matrix

The electrical and electroluminescence properties of a single narrow-gap heterostructure based on a p-n junction in indium arsenide, containing a single layer of InSb quantum dots in the InAs matrix, are studied. The presence of quantum dots has a significant effect on the shape of the reverse branch of the current-voltage characteristic of the heterostructure. Under reverse bias, the room-temperature electroluminescence spectra of the heterostructure with quantum dots, in addition to a negative-luminescence band with a maximum at the wavelength λ = 3.5 μm, contained a positive-luminescence emission band at 3.8 μm, caused by radiative transitions involving localized states of quantum dots at the type-II InSb/InAs heterointerface.     

Ferromagnetic semiconducting materials: Methods of studies and control of parameters (Review)

Methods used for designing and controlling parameters of prototypes of ferromagnetic semicon-ducting materials are described. Examples of applications of the above methods are given. The up-to-date ferromagnetic semiconductor design level for spin applications is briefly considered.