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A method for physical modeling of the influence of bulk leakage-current channels (dislocations) on the electrophysical and lighting characteristics of LEDs by connecting the p–n junction of an LED in parallel to an ohmic resistance or another p–n junction is described. The relationships that allow one to determine the change in the electrophysical and lighting characteristics of LEDs under the influence of various external factors (ionizing radiation, long-term operation, etc.) have been established. Using the obtained relationships, it is possible to determine the electrophysical characteristics of dislocations according to the changes in the electrophysical and lighting characteristics of LEDs, taking the role of dislocations into account. Based on the literature data, the efficiency of using the established relationships in the analysis of the characteristics of LEDs that are exposed to external impacts has been shown.

—A technique for studying the resistance of IR-wavelength LEDs to the action of fast neutrons at the IRT-T reactor is described. A thermal neutron filter based on boron carbide and cadmium has been developed for the GEC-6 horizontal experimental channel of the IRT-T reactor. The identity of degradation processes in LEDs is shown when exposed to fast neutrons with pulsed (BARS-4 reactor) and continuous (GEC-6 of IRT-T reactor) fluence. The developed technique can be recommended for studying the resistance of various materials and electronic products to the action of fast neutrons in various irradiation regimes.

In this study we investigated the dependences of the rate of ion-beam etching of the upper contact layer (GaAs:Si), an active region consisting of a 50-fold alternation of barrier layers (AlxGa1–xAs) and quantum wells (GaAs:Si) and the lower contact layer (GaAs:Si) along the depth of QWIP structures based on GaAs–AlGaAs, fabricated by molecular beam epitaxy (MBE), in order to determine the effect of the composition of various layers on the etching rate and the ability to complete the etching process to the desired depth in time.

UV visible-blind and solar-blind 320 × 256 photodiode arrays based on AlxGa1 – xN heteroepitaxial structures (AlGaN HES) and sensitive in the near-ultraviolet range of 0.2–0.4 μm have been created and studied. The AlGaN HES were grown by organometallic vapor deposition (MOCVD) and molecular beam epitaxy (MBE) on sapphire substrates. To reduce structural defects, the state of the surface and the surface layer of epipolished sapphire substrates was investigated, and a finishing technology was developed. UV FPAs in the AlGaN HES were produced by ion etching. The dark current components for AlGaN photodiodes were simulated. The main dark current components, such as generation–recombination, shunting leakage, hopping conductivity, and Poole–Frenkel components, are calculated. The possibility of achieving photoelectric parameters on the level of the best foreign counterparts is demonstrated.

A topical problem of photoelectronics is the development of array photodetector devices of the near infrared spectral range based on the InxGa1–xAs/InP epitaxial layers of the megapixel format. In this paper, we present the results of studies of current–voltage characteristics of photosensitive elements in arrays of the 320 × 256 format with a step of 30 μm based on heteroepitaxial structures with an InGaAs absorbing layer on InP short-wave infrared substrates. Arrays of photosensitive elements (PSEs) are fabricated using planar, mesa, and mesa planar technologies based on nB(Al0.48In0.52As)p-structures. In arrays produced using the mesa planar technology based on nB(Al0.48In0.52As)p-structures, small dark current and ampere–watt sensitivity to IR radiation of the 1–1.7 μm range are shown to combine successfully at low bias voltages. Electrophysical parameters of functional layers of initial heteroepitaxial n-B-p structures affect efficiently the dark currents and ampere–watt sensitivity of the array elements. Based on these studies, parameters of the n-B(Al0.48In0.52As) functional layers of p-structures were optimized and high-efficiency photodiode arrays of the 320 × 256 format with a step of 30 μm and structures of the 640 × 512 format with a step of 15 μm were fabricated with a defectiveness not exceeding 0.5%.

I–V characteristics and spectral photosensitivities of photodiodes based on epitaxially grown hydrides of metal-organic compounds (MOC-hydride epitaxy) of epitaxial structures with the In0.67Ga0.33As absorbing layer doped with Zn on the InP substrates are studied. The photodiodes are fabricated using the mesatechnology. The long-wavelength boundary of the spectral photosensitivity of diodes measured at half-maximum is 2.06 μm at room temperature. Photosensitivity spectra are studied in a temperature interval of 230–300 K.

The 320 × 256 focal plane arrays based on р + -B–n-N + tetralayer heterostructures with a wide-gap barrier layer have been investigated. The heterostructures with a narrow-gap n-InGaAs absorbing layer were grown by means of metalorganic vapor phase epitaxy on InP substrates. The band discontinuity between the In0.53Ga0.47As absorbing layer and the In0.52Al0.48As barrier layer is removed by growing a thin four-component n-AlInGaAs layer with the bandgap gradient variation. Delta-doped layers included into the heterostructures make it possible to lower the barrier in the valence band and eliminate the nonmonotonicity of energy levels. The experimental study of the dark current has been performed. It has been revealed that the average value of the dark current does not exceed 10 fA for the photodiode arrays with a pitch of 30 μm.

SWIR ADP 320 × 256 FPAs based on p–i–n photodiodes in InGaAs heterostructures have been developed and investigated. The typical InGaAs/InP PIN heterostructures are formed by Metal Organic Vapor Phase Epitaxy (MOVPE) on n + type InP substrates. The InGaAs/InP PIN photodiodes performance have been estimated by measuring current-voltage characteristics. APD arrays are designed using a mesa-passivated avalanche photodiode device array of p–i–n junctions in heterostructure with common absorption and multiplication regions. The optimal operating point for managing avalanche application depended on various factors has been started at 15 V bias and the multiplication coefficient was of 2–4.

Mesaelements of the focal plane array (FPA) of p–i–n diodes based on AlxGa1–xN for p–i–n heteroepitaxial structures (HESs) grown by the molecular-beam epitaxy and hydride epitaxy methods with the use of metalorganic compounds are formed. Elements of 320 × 256 FPAs with a pitch of 30 μm are separated by means of ion-beam etching through a photoresist mask in the argon ion stream produced by the Kaufmann ion source in a vacuum plant. To determine the required etching depth, contact profilometry and ultraviolet spectrophotometry methods allowing one to determine positions of the n-layer and sufficient etching depth of the sample are used. The thickness accuracy of the HES functional layers stated in manufacturer’s certificates does not exceed 28%. Rates of ion-beam etching of AlxGa1–xN for p–i–n layers with different compositions are determined.

The reaction of (Z)-1-arylmethylidene-5,5-dimethyl-3-oxopyrazolidin-1-ium-2-ides with para-substituted N-arylmaleimides at 110°C is cis-stereoselective [cis/trans-adduct ratio ≥(9–10): 1]. Under analogous conditions, the conversion of (Z)-1-(2,6-dichlorophenylmethylidene)-5,5-dimethyl-3-oxopyrazolidin-1-ium-2-ide in the reaction with N-(4-methoxyphenyl)maleimide in 6-7 h did not exceed 1–2%. The cycloaddition of (Z)-1-ethylidene- and (Z)-1-(2-methylpropylidene)-5,5-dimethyl-3-oxopyrazolidin-1-ium-2-ides to N-arylmaleimides, regardless of the substituent in the phenyl group of the latter, gave preferentially the corresponding trans-adducts, which cannot be rationalized only by steric effect of substituents in terms of the concerted mechanism.

Reactions of (Z)-1-arylmethylidene-3-oxopyrazolidin-1-ium-2-ides (stable analogs of azomethine imines generated by thermal opening of the diaziridine fragment in 6-aryl-1,5-diazabicyclo[3.1.0]hexanes) with N-arylmaleimides having no ortho substituents in the aryl group are stereoselective: the products are mixtures of the corresponding cis and trans adducts, the latter prevailing (∼1.4–2.6: 1). trans Adducts are formed as the only products in the reactions with di-ortho-substituted N-arylmaleimides. (Z)-1-[(2,6-Dichlorophenyl) methylidene]-3-oxopyrazolidin-1-ium-2-ide reacts with both para- and ortho-substituted N-arylmaleimides to give exclusively trans adducts. Labile azomethine imines generated by thermolysis of 6-aryl-1,5-diazabicyclo[3.1.0]hexanes are likely to have Z configuration as well.

Thin layer chromatography (TLC) is the simplest and a rather efficient version of liquid chromatography and is widely used in analytical practice. In Russia, thin layer chromatography is used in more than 10000 laboratories. Therefore, further development of this liquid chromatography technique and an increase in its resolution and quickness are of common interest. As a further development of TLC, in this study, for the control of the chromatographic process, a carrier gas stream was passed above the plate with the absorption layer directly during separation and this technique was experimentally substantiated. According to the common opinion of researchers who actively and fruitfully use TLC, a key drawback of this technique is the presence of a gas volume in contact with the sorption layer of the plate during the separation [1‐4]. However, useless things are those for which no useful application has been found as yet.