Vol 46, No 7 (2017)

The effect of the excess hole capture efficiency on carrier accumulation with increasing photoexcitation in quantum wells of the n-AlGaAs/GaAs heterostructures is investigated. The oscillatory character of the dependence of the ratio between the intensities of photoluminescence from the quantum well and barrier layers on the well width is demonstrated. The hole capture times in the oscillation maximum and minimum are estimated as 3 and 370 ps. The shift of the energy transition in a resonant well under strong excitation is attributed to the charge buildup effect caused by the difference between the electron and hole capture rates.

Features of diffractometry multilayer heterostructures based on gallium nitride have been considered. Using a Vector-GaN instrument for X-ray diffractometry, the effect of the technological conditions of the preparation of the layers of the GaAlN/InGaN/GaN/Al₂O₃ heterostructure on their structural perfection has been demonstrated.

The results of experimental studies of the Pt structure with the thickness ranging from (0.48 ± 0.1) to (24.38 ± 0.1) nm ion beam including deposition by focused ion beam are presented. The rate of ion beam including deposition of Pt, which depending on the modes varies from (0.28 ± 0.02) to (6.7 ± 0.5) nm/s, is determined experimentally. The deviation of Pt lateral structure sizes from those preset by the template decreases from (29.3 ± 0.07)% to (2.4 ± 0.2)% depending on the deposition duration. By the thicknesses of Pt nanosized structures larger than 3 nm, their specific resistance amounts to (23.4 ± 1.8) Ohm cm and weakly depends on the thickness. The results can be used for developing the technological processes used to form the structures of microelectronics sensorics, nanoelectronics, and nano- and microsystem engineering.

The features of modern complementary bipolar technologies (CB-technologies) for analog applications have been analyzed and the main trends in their development are considered. Different industrial CBtechnologies are compared on the basis of two parameters of complementarity, namely the quality factor (βV_A) and Johnson’s parameter (BV_CEOf_T). The p-epitaxial-planar CB-technology has been studied by the method of two-dimensional numerical simulation using the TCAD Sentaurus software for vertical n–p–n and p–n–p transistors. A careful calibration of the parameters of technological and electrophysical 2D models on the basis of test structures has shown sufficient accuracy of the used methodology for practice.

The radiation stability of AlGaN/GaN HEMT millimeter-wave signal converters with highly mobile electrons irradiated by neutron and gamma radiation is investigated. The following characteristics have been chosen as the parameters for estimating the stability: the output microwave signal range, conversion factor, and the total consumed current. The consumed current dependence on the absorbed dose of gamma radiation and the sample temperature is determined. It is shown that the effect of neutron irradiation upon the characteristics is insignificant, although the gamma irradiation results in a considerable increase of the current consumed due to the formation of nitrogen donor vacancies, annealing of growth acceptor defects, and defect ordering. Six months later, the parameters of the devices returned to the initial values, indicating the restoration of the original state of the substrate’s crystal structure.

Being unavailable in the literature for the past few recent decades, the cellular automata formulations of some algorithms for sorting character and string arrays are considered here. A cellular automaton multiplying two integers written in a numeral system with an arbitrary basis is proposed for the first time. The algorithm is based on the Atrubin parallel multiplication scheme for a systolic array of processors and requires four components (registers) instead of five.

Methods to accelerate transient processes in frequency spectrum synthesizers based on the pulse phase-locked loop are considered. Methods to accelerate the output voltage of the loop filter unit when using the equivalent capacitance multiplication of the capacitor methods based on the circuits with an additional current source in the charge pump current source (CPCS) unit are proposed. Diagrams of transient processes for the automatic control of the output frequency are presented. The diagrams confirm that using the proposed decisions for control by an additional current source of the CPCS unit makes it possible to approximate the transition process to the optimal value of the response speed.

The complex study results of the parameters of TiN/Ti diffusion-barrier structures using the methods of relative X-ray reflectometry and diffuse scattering of X-ray radiation implemented by a two-wavelength X-ray optical measurement scheme are presented. It is shown that this scheme, by a single measurement, enables studying two different diffuse scattering regions, which increases the correctness and unambiguity of the analysis that was carried out. The considered complex of methods makes it possible to solve the ambiguity of a density/roughness type by the solution of the inverse reflectometry problem and to calculate the parameters of buried layers in the structures which were studied.