Modeling and characterization of photovaractor for microwave optoelectronics abstract

Optical control of microwave circuits using photodiode junction capacitance variation due to optical illumination has some advantages such as simplicity and wide possibilities in application, high tuning range, accuracy, and speed. We have proposed to call as photovaractor the device which capacitance changes under illumination and which is used for optical control of microwave circuits. The numerical one-dimensional drift-diffusion model of the photovaractor based on the InP/InGaAs/InGaAsP heterostructure which is taking into account influence of the external electric circuit and parasitic elements was used to calculate the junction capacitance change under illumination. The experimental results and theoretical study of the photovaractor in the frequency range up to 3 GHz are presented

Application of hydrogenation to low-temperature cleaning of the Si(001) surface in the processes of molecular-beam epitaxy: Investigation by STM, RHEED and HRTEM

Structural properties of the clean Si(001) surface obtained as a result of low-temperature (470--650C) pre-growth annealings of silicon wafers in a molecular-beam epitaxy chamber have been investigated. To decrease the cleaning temperature, a silicon surface was hydrogenated in the process of a preliminary chemical treatment in HF and NH_4F aqueous solutions. It has been shown that smooth surfaces composed by wide terraces separated by monoatomic steps can be obtained by dehydrogenation at the temperatures > 600C, whereas clean surfaces obtained at the temperatures < 600C are rough. It has been found that there exists a dependence of structural properties of clean surfaces on the temperature of hydrogen thermal desorption and the process of the preliminary chemical treatment. The frequency of detachment/attachment of Si dimers from/to the steps and effect of the Ehrlich-Schwoebel barrier on ad-dimer migration across steps have been found to be the most probable factors determining a degree of the resultant surface roughness.Comment: 8 pages, 8 figures; version accepted to J. Appl. Phy

Metal silicide/poly-Si Schottky diodes for uncooled microbolometers

Nickel silicide Schottky diodes formed on polycrystalline Si films are proposed as temperature sensors of monolithic uncooled microbolometer IR focal plane arrays. Structure and composition of nickel silicide/polycrystalline silicon films synthesized in a low-temperature process are examined by means of transmission electron microscopy. The Ni silicide is identified as multi-phase compound composed by 20 to 40% of Ni3Si, 30 to 60% of Ni2Si and 10 to 30% of NiSi with probable minor content of NiSi2 at the silicide/poly-Si interface. Rectification ratios of the Schottky diodes vary from ~100 to ~20 for the temperature increasing from 22 to 70C; they exceed 1000 at 80K. A barrier of ~0.95 eV is found to control the photovoltage spectra at room temperature. A set of barriers is observed in photo-emf spectra at 80K and attributed to the Ni-silicide/poly-Si interface. Absolute values of temperature coefficients of voltage and current are found to vary from 0.3 to 0.6%/K for forward biasing and around 2.5%/K for reverse biasing of the diodes.Comment: 18 pages, 7 figure

Improving Methods for the Assessment of the Innovative Potential of the Organization on the Example of OJSC «Berezovsky Cheese-Making Plant»

The essence of the innovative capacity has been determined. The proposed method of the integrated assessment of the innovation is based on two modules: scientific-technical and industrial-financial, which includes a number of indicators that characterize the innovative condition of the organization. Also, the innovative capacity has been analyzed on the example of OJSC "Berezovsky Cheese-making Plant" in accordance with this method

Improving Methods for the Assessment of the Innovative Potential of the Organization on the Example of OJSC «Berezovsky Cheese-Making Plant»

The essence of the innovative capacity has been determined. The proposed method of the integrated assessment of the innovation is based on two modules: scientific-technical and industrial-financial, which includes a number of indicators that characterize the innovative condition of the organization. Also, the innovative capacity has been analyzed on the example of OJSC "Berezovsky Cheese-making Plant" in accordance with this method

Study of the process of interaction between low-frequency ultrasound and biological tissue phantoms

This paper presents the results of a series of experimental studies on the impact of low-frequency ultrasound on biological tissue phantoms, acoustic pressure on the motion of particles in an acoustic field generated by annular waveguide. Experiments have demonstrated that when vibrations with a frequency corresponding to its natural frequency of bending vibrations are induced in the annular waveguide, micropowder particles form arranged bulk structures on the substrate. Analysis of results on the behavior of micropowder particles in the ring insonation area revealed that frequency variations of ultrasonic vibrations lead to variations in spatial distribution of acoustic pressure inside the ring. The thermal effect of low-frequency ultrasound from annular waveguide on biological tissue phantoms has been studied. It was established that the annular waveguide enables heating of fluid when it has no direct contact with the media, thereby demonstrating its applicability for non-contact treatment of tumors