In this, work some aspects of the development of the visual system of Nothobranchius guentheri at the main stages of ontogenesis were described for the first time. It was possible to establish that the formation of the visual system occurs similarly to other representatives of the order Cyprinodontiformes, but significantly differs in terms of the individual stages of embryogenesis due to the presence of diapause. In the postembryonic period, there is a further increase in the size of the fish’s eyes and head, to the proportions characteristic of adult fish. The histological structure of the eye in adult N. guentheri practically does not differ from most teleost fish living in the same environmental conditions. The study of the structure of the retina showed the heterogeneity of the thickness of the temporal and nasal areas, which indicates the predominant role of peripheral vision. Morphoanatomical measurements of the body and eyes of N. guentheri showed that their correlation was conservative. This indicates an important role of the visual system for the survival of fish in natural conditions, both for the young and adults. In individuals of the older age group, a decrease in the amount of sodium (Na) and an increase in magnesium (Mg) and calcium (Ca) were found in the eye lens. Such changes in the elemental composition of the lens can be a sign of the initial stage of cataractogenesis and disturbances in the metabolism of lens fibers as a result of aging. This allows us to propose N. guentheri as a model for studying the structure, formation, and aging of the visual and nervous systems.

Аннотация. Проведены исследования фотолюминесценции и темновых вольт-амперных характе-ристик гетероструктур InAs/GaAs с тремя типами потенциальных барьеров для квантовых точек: GaAs, Al 0,2 Ga 0,8 As, Al 0,4 Ga 0,6 As. Гетероструктуры выращены методом ионно-лучевой кристаллизации. Наличие пиков излучения фотолюминесценции, обусловленных смачивающим слоем для трех типов потенци-альных барьеров, свидетельствует о росте квантовых точек InAs в режиме Странского -Крастанова. Введение в конструкцию широкозонных барьеров AlGaAs приводит к смещению пика излучения фо-толюминесценции основных состояний GS в квантовых точках InAs в высокоэнергетическую область (синее смещение) и увеличивает интенсивность пика. В случае использования барьеров Al x Ga 1-x As ха-рактерным признаком является уменьшение ширины пика излучения на половине максимума излуче-ния в сравнении с потенциальными барьерами GaAs. Изменение состава тройного твердого раствора Al x Ga 1-x As с x = 0,2 до x = 0,4 ат. %, покрывающего сверху квантовые точки InAs, приводит к повыше-нию интенсивности пика излучения основных состояний квантовых точек. Результаты исследования темновых вольт-амперных характеристик экспериментальных образцов показывают, что доминирую-щими механизмами переноса носителей заряда являются термоэлектронная эмиссия и туннелирова-ние, стимулированное внешним электрическим полем. Использование широкозонных потенциальных барьеров AlGaAs вместо GaAs способствует уменьшению напряжения смещения (до 0,48 В), при ко-тором происходит изменение механизма переноса носителей заряда с термоэмиссионного на туннели-рование, стимулированное внешним электрическим полем. Введение потенциального барьера состава Al 0,4 Ga 0,6 As позволяет добиться минимального темнового тока 10 -9 А в гетероструктурах InAs/GaAs с квантовыми точками.Ключевые слова: гетероструктуры InAs/GaAs, ИК-диапазон, барьер AlGaAs, оптоэлектроника, тройные твердые растворы на основе AIIIBV. abstract. Research has been conducted on the photoluminescence and the dark current-voltage characteristics of InAs/GaAs heterostructures with three types of potential barriers to the quantum dots: GaAs, Al 0,2 Ga 0,8 As, Al 0,4 Ga 0,6 As. Heterostructures were grown with an ion-beam crystallization method. The presence of the photoluminescence emission peaks specified by the wetting layer for the three types of potential barriers shows the Stransky Krastanow growth mode of InAs quantum dots. The introduction of wide-AlGaAs barriers into the design leads to the shift of the photoluminescence emission peak of the ground states (GS) in the InAs quantum dots into the high-energy region (blue shift) and increases the peak intensity. In case of Al x Ga 1-x As barrier usage the characteristic feature is the reduction of the emission peak width at half maximum of the emission, in comparison with the potential barriers of GaAs. It is shown that the change in the composition of the ternary solid solution Al x Ga 1-x As from x = 0.2 to x = 0.4 at. % which coats the InAs quantum dots from 1 Южный научный центр Росс...

The results of the presented studies demonstrate the possibility of using two and three component solid solutions, based on elements of the A3B5 groups, as thin barrier layers to cover an array of structured InAs quantum dots for photoactive heterointerfaces of solar energy. When using three-component solid solutions for QD barrier layers, a decrease in the thermionic generation in the near infrared spectrum and a decrease in the dark current of the heterointerface are obtained.

In this paper, we investigate heterostructures with an array of InAs quantum dots encapsulated by GaAs barrier layers obtained by ion-beam epitaxy. The thickness of the layers was less than 30 nm. It is shown that this technique allows to obtain quantum dots with lateral dimensions up to 50 nm with a height of 10 nm. The density of the obtained array of quantum dots was 109 cm−2. The studies performed using photoluminescence methods revealed the peaks of the main transitions for quantum dots at 1.1 eV (1150 nm) for samples with GaAs barrier, which corresponds to the near-infrared. The width of the main peak of the samples was about 0.2-0.25 eV, which is associated with the dispersion of quantum dots sizes. Dark current-voltage characteristics of the structures proved that the value of dark current density at 90 K is about 10−6 A/cm2. The asymmetry of the dark current curves at positive and negative shifts is determined. The samples also showed that an increase of temperature leads to degradation of characteristics. When the operating temperature rises to 300 K, the density of the dark current changes in the range from 0.1 to 0.01 A/cm2.