Theoretical analysis of the radiation effect on the transient behavior of optoelectronic integrated devices

Theoretical analysis of the radiation effect on transient behavior of an optoelectronic integrated device composed of a heterojunction phototransistor and a light emitting diode is studied theoretically. First, the transient behavior and the rise time of this device before radiation are investigated based on the frequency response of the constituent devices and the optical feedback inside the device. Second, the effect of neutron irradiation flux on the transient behavior of this device is theoretically studied. The results show that, by increasing the optical feedback inside the device, the rise time in the amplification mode is increased along with an increasing output, while that in the switching mode can be reduced effectively, and the neutron irradiation reduces the transient response and the rise time in both the amplification and switching modes. This type of model can be exploited as optical amplifier, optical switching device, and other applications.     

Structural and some electrophysical properties of the solid solutions Si1 − x Sn x (0 ≤ x ≤ 0.04)

Films of the solid solutions Si_{1 ? x} Sn _x (0 ≤ x ≤ 0.04) on Si substrates have been grown by liquid phase epitaxy. The structural features of the films have been investigated using X-ray diffraction. The temperature behavior of current-voltage characteristics and the spectral dependence of the photocurrent for the heterostructures p-Si-n-Si_{1 ? x} Sn _x (0 ≤ x ≤ 0.04) have been analyzed. The grown epitaxial films of the solid solutions Si_{1 ? x} Sn _x (0 ≤ x ≤ 0.04) have a perfect single-crystal structure with a (111) orientation and a subgrain size of 60 nm. In the epitaxial films at the Si-SiO₂ interfaces between silicon subgrains and SiO₂ nanocrystals, where there are many sites with a high potential, the Sn ions with a high probability substitute for the Si ions and encourage the formation of Sn nanocrystals with different orientations and, as follows from the analysis of the X-ray diffraction patterns, with different sizes: 8 nm (for the (101) orientation) and 12 nm (for the (200) orientation). The current-voltage characteristics of the heterostructures p-Si-n-Si_{1 ? x} Sn _x (0 ≤ x ≤ 0.04) are described by the exponential law J = J ₀exp(qV/ckT) at low voltages (V < 0.2 V) and the square law J = (9qμ _p τ _p μ _n N _d /8d ³)V ² at high voltages (V > 1 V). These results have been explained by the drift mechanism of charge carrier transport in the electrical resistance relaxation mode.     

Cooling rate dependency of fluctuations in the melt volume of amorphous materials

Fluctuations in the melt volume of the amorphous materials as a function of cooling rate is established. The observed dependency is similar to the one found for the glass transition temperature (the Bartenev-Ritland equation). The constant ratio of the empirical parameters in the equation is explained in terms of the excited state model.     

Anharmonicity of lattice vibrations and the fluctuation volume of amorphous substances near the glass transition temperature

The fraction of the fluctuation volume (in a model of the excited state) at the glass transition temperature depends linearly on the Gruneisen parameter, i.e., the degree of the anharmonicity of lattice vibrations in amorphous polymers and glasses.     

Regularities of Phosphides Formation on Phosphorus Interaction with Elements

Abstract

During phosphide synthesis from elements in the evacuated tubes the reaction rate is controlled, as a rule, by the diffusion of element ions through solid phosphide layers. Such a synthesis takes a number of hours. During interaction under combustion regime (1) the reaction region spreads over the powder mixture of metal and phosphorus, the phosphorus evaporates and interacts with the heated metal. Then a liquid phase with composition close to the eutectic is formed, which dissolves metal particles and is simultaneously enriched with phosphorus with heat liberation. The liquid phase provides high reaction rates and the synthesis is finished after some seconds. During interaction in ternary systems, e.g. Ni-Fe, Cu, Mo, Ti, Cr, B-P, Fe-Mo-P, Cu-Zr-P, as a rule, solid solutions or mixtures of binary and ternary phosphides, seldom individual phosphides, are formed. A study of the interaction reactions under combustion regime between the red phosphorus and oxides of some metals (Cu, Fe, Co, Ni) resulting in phosphides and phosphates formation was carried out. In aqueous medium phosphorus interacts with Cu, Ag, Au ions, and those of platinoids Interaction of copper sulphate with yellow phosphorus aqueous dispertion was studied in detail. As a result of P°) phosphorus disproportioning copper phosphide Cu₃P (P_3-) and orto-phosphoric acid (P⁵⁺) are formed.     

Synthesis,structure, and growth-promoting activity of 1-alkyl-4-(3-naphthyloxyprop-1-ynyl)piperidin-4-ols

Alkylation of 1- and 2-naphthols with propargyl bromide in acetone in the presence of potassium carbonate led to prop-2-ynyloxynaphthalenes, which upon reaction with 1-alkyl-piperidin-4-ones under the Favorsky conditions afforded the corresponding tertiary alcohols. 1-Methyl-4-[3-(2-naphthyloxy)prop-1-ynyl]piperidin-4-ol hydrochloride was found to possess a high growth-promoting activity in the concentration of 0.001% upon the pre-sowing treatment of beetroot seeds and potatoes and increase their productivity by ～20%.     

Synthesis of polyfunctional polyconjugated oligomers of 4-aminophenol and their use in obtaining of antistatic composite materials

Polyconjugated oligomers containing aromatic links with hydroxyl and amino functional groups were synthesized by oxidative polycondensation of 4-aminophenol. They exhibit solubility and fusibility, heat resistant, paramagnetic and semiconductor properties, and also high reactivity in reactions characteristic for aromatic hydroxyl groups. These oligomers were used as supplements to industrial polymers. Composite materials were obtained including a rubber with high physico-mechanical, thermal, and electrical properties.     

Autohesion of amorphous polymers: a fractal model

The development of shear strength of an autohesion contact for two amorphous polymers is investigated in the framework of fractal analysis. It is shown that the shear strength depends on the number of macromolecular intersections and mutual diffusion in the boundary layer. The data for both analyzed polymers are described by one equation.