In this article the layout and structure of the microwave switcher based on the managed electron density maximum rearrangement in multi-contacts functionally integrated active region are considered. The basis of the microwave switcher is a normally opened high electron mobility transistor structure (HEMT) with multiple Schottky gates and the corresponding number of switching ohmic contacts. In this research two-dimensional finite-difference physical and topological model of the considered microwave switchers is proposed. The distinctive features of the proposed model are combination of two different sets of variables and explicit first-order upwind discretization scheme for the normalized continuity equation. The obtained results of numerical modeling are discussed.
In the report the linear acceleration sensor design with three axis of sensitivity is researched. Parameterized geometry and finite element model for modal analysis are developed in the ANSYS program. Behavioral description of the study design is developed with language VHDL-AMS to simulate the sensor operation under the influence of linear acceleration along three axis of sensitivity. On the basis of research results three-axis device sensitivity, cross-sensitivity, duration transients are specified. As part of the work the experimental sensor prototypes are fabricated.
In this paper, we consider the issue of research and development of on-chip optoelectronic devices designed for the optical interconnecting of integrated circuit elements. We address the conceptual on-chip optical interconnections based on AIIIBV nanoheterostructure lasers with functionally integrated modulators of optical radiation. According to the estimations, these optoelectronic devices can generate subpicosecond optical pulses. The paper is aimed at the development of numerical models, simulation methods, and specialized software. These aids are intended for the research of physical processes taking place in high-speed heterostructure photodetectors suitable for operation as parts of on-chip optical interconnections together with the lasers-modulators. We propose to utilize the drift-diffusion approximation of the semiclassical approach for the numerical simulation of charge carrier transport and accumulation in semiconductor photosensitive heterostructures. The drift-diffusion numerical simulation technique was developed. This technique is based on the application of the Newton method, implicit difference scheme, and Slotboom drift-diffusion formulation in terms of electron and hole imref exponents and electrostatic potential. We researched p+-Al0.3Ga0.7As/i-GaAs/n+-Al0.3Ga0.7As and metal/n-Al0.3Ga0.7As/n+-GaAs heterostructures. Rise and fall times of the devices being considered are approximately equal and amount to about 1.6 ps for the p-i-n structure and 1.7 ps for the Schottky-barrier photodiode. We concluded that it is reasonable to develop the methods directed at the improvement of photodetector response speed.
A method of signal processing devices design for micromechanical accelerometers with capacitive transducers is proposed. This method provides the complex solution of the sensibility increasing and noise immunity problems by finding of the difference frequency of signals, which are formed by two identical generators with micromechanical capacitive transducers in frequency control circuits. In this study the analog and digital versions of the highly sensitive signal processing devices circuits with frequency output were developed. The breadboards of these devices are fabricated and studied and the project of their integral realization is designed.
This paper describes the application of electrical impedance tomography (EIT) to development of the surface defect sensor that can be used for structural health monitoring (such structural as bridge bearing, airframe, etc.). Thin conductive film with electrodes along its boundaries, as a sensor skin, is applied to structural surface. By using the corresponding boundary potential measurements and the value of applied current the both forward and inverse EIT problem were solved and method of defects detection in thin conductive film was created. This method allows calculating two-dimensional distribution of conductivity in film (conductivity map) and, indirectly, distribution of defects in it. The reconstruction defect efficiency criterion and the method of its calculation were proposed. The influence of initial data disturbance (non-uniform conductivity of the film as its roughness) on reconstruction defect efficiency without using all the combinations of current electrodes was examined.
Physical-topological model of injection lasers with a functionally integrated optical radiation modulators, allowing to carry out the numerical analysis of transient processes in lasers-modulators taking into account the additional crosscontrol field and the irregular electrons, holes and photons spatial distributions was proposed. The results of numerical modeling of conventional double heterostructure lasers and functionally-integrated lasers-modulators was presented. The results of numerical modeling and the limits of applicability of the proposed model was analyzed.