The epitaxial growth technique of InGaAs photodiode structures based on a digital InGaAs/GaAs metamorphic buffer layer by metalorganic chemical vapor deposition has been developed. The spectral dependence of the photocurrent of photodiodes based on the produced structures has a maximum at the 1.16 µm wavelength. The photosensitivity range at 10% of peak is 0.99 - 1.33 µm at room temperature. The current-voltage characteristics in the temperature range 9–300 K were investigated. It is shown that the dark current consists of generation-recombination and tunneling components. The dark current density at room temperature was 8×10 -5 A/cm 2 with a reverse bias of -5 V.

The properties of multilayer (up to 80 layers) nanoperiodic (period up to ~12 nm) Al 2 O 3 /Ge and Al 2 O 3 /Si/Ge/Si systems annealed in a nitrogen atmosphere at temperatures from 700 to 900°C are studied using transmission electron microscopy, X-ray techniques of photoelectron spectroscopy, diffractometry, and reflectometry, and optical methods of photoluminescence and Raman scattering. In Al 2 O 3 /Ge samples annealed at 700°C, the formation of Ge nanocrystals with a size of ~3 nm is detected, which disappear at 800–900°C, when nanocrystals of the Al 6 Ge 5 semiconductor phase of large size (>100 nm) grow. The introduction of separating layers of Si (Al 2 O 3 /Si/Ge/Si) leads to the formation of nanocrystals of the SiGe x alloy at a temperature of 800°C, above which the size of the crystallites of this phase is about ~3–4 nm. The data obtained using X-ray techniques are in good agreement with the results of high-resolution transmission electron microscopy and Raman spectroscopy. In the Al 2 O 3 /Ge samples, photoluminescence is observed at room temperature at ~2.1 eV, and in the Al 2 O 3 /Si/Ge/Si samples, there is an additional luminescence peak at ~1.4 eV. Hydrogenation of the samples by annealing in a hydrogen atmosphere at 500°C enhances the luminescence intensity.

We report on the fabrication and investigation of prototype optically controlled memristors based on ZrO2(Y) (12% mol. Y2O3) with Au nanoparticles (NPs) of 2-3 nm in diameter formed by layer-by-layer magnetron deposition of ZrO2(Y)/Au/ZrO2(Y) stacks fol-lowed by annealing. The upper contacts of the memristor stacks were made from indium-tin oxide (ITO) to provide the access of photoexcitation to the active Au NP array. The cross -point memristor devices with the active region sizes of 2020 & mu;m2 were defined by standard photolithography with wet etching. A shift of the switching voltages from the high resistance state into the low resistance one and back has been observed under the photoexcitation at the wavelength of 650 nm corresponding to the collective plasmon resonance in the dense Au NP array. The effect was related to the charging of the Au NPs due to the internal photoemission of the electrons from the Au NPs into the ZrO2(Y) matrix enhanced by the plasmon resonance. It leads to the redistribution of the electric field near the Au NPs that, in turn, stimulates the switching process. The optically-controlled memristors investigated are promising for applica-tion in various fields of memristive photonics.

Annealing of amorphous TiOx films obtained by electron-beam evaporation under atmospheric conditions at temperatures from 300 to 400°C is found to lead to the formation of an anatase crystalline phase. According to Raman spectroscopy data, the increase in the fraction of the the crystalline phase stops at an annealing temperature above 350°C. According to the results of X-ray phase analysis, the average crystallite diameter is about 23 nm. Electron microscopy studies have shown that, upon annealing, the near-surface layer (15 nm thick) crystallizes in the films, and TiO2 nanocrystals with sizes from 4 to 10 nm are formed in the bulk. As the depth increases, the number of nanocrystals decreases.

The annealing of amorphous TiO x films obtained by electron-beam evaporation under atmospheric conditions at temperatures from 300 to 400°C is found to lead to the formation of an anatase crystalline phase. According to Raman spectroscopy data, the increase in the fraction of the crystalline phase stops at an annealing temperature above 350°C. According to the results of X-ray diffraction analysis, the average crystallite diameter is about 23 nm. Electron-microscopy studies show that, upon annealing, the surface layer (15 nm thick) crystallizes in the films, and TiO 2 nanocrystals with sizes from 4 to 10 nm are formed in the bulk. As the depth increases, the number of nanocrystals decreases.

The effect of optical radiation in the visible and near-infrared bands on resistive switching of a MOS stack based on ZrO2(Y) film on an n-Si(001) substrate with self-assembled Ge nanoislands on its surface has been studied. An increase in the resistive switching logical gap was observed upon the photoexcitation, in particular, when the photon energies were smaller than the Si band gap. The effect was associated with the impact of the photovoltage at the Si/Ge/ZrO2(Y) interface. In the latter case, the effect is associated with spatially indirect interband optical transitions in Ge nanoislands.

The effect of optical radiation in the visible and near-infrared bands on resistive switching of a MOS stack based on ZrO2(Y) film on an n-Si(001) substrate with self-assembled Ge nanoislands on its surface has been studied. An increase in the resistive switching logical gap was observed upon the photoexcitation, in particular, when the photon energies were smaller than the Si band gap. The effect was associated with the impact of the photo-emf at the Si/Ge/ZrO2(Y) interface. In the latter case, the effect is associated with spatially indirect interband optical transitions in Ge nanoislands. Keywords:: memristor, photo-induced resistive switching, yttria-stabilized zirconia, MIS-structure, Ge/Si nanoislands.

The effect of optical illumination in the visible band on the resistive switching in ITO/ZrO2(Y)/n-Si metal-oxide-semiconductor (MOS) structures (including those with Au nanoparticles embedded in the ZrO2(Y) layer) is studied. It is found that the dependence of the logical gap between the resistance states on the photoexcitation intensity had a threshold nature. The logical gap decreases with further increasing photoexcitation intensity above the threshold. This effect is ascribed to the heating of active layers of the MOS structure due to interband optical absorption in the Si substrate. The suppression of resistive switching by photoexcitation at a wavelength of 650 nm (corresponding to plasmon resonance in Au nanoparticles) due to plasmon optical absorption in nanoparticles is observed.

Multi-layered nanosized Al2O3/Ge/Si structures manufactured by electron-beam evaporation and annealed at a temperature within the range 700−900◦C are examined using transmission electron microscopy, Raman spectroscopy and X-ray diffraction techniques. The periodic structure with a good layer planarity is confirmed to retain after heat treatment up to 900◦C. At an annealing temperature above 700◦C, nanocrystallites with a bimodal size distribution start to form within initially amorphous Ge layers, the mean size of small crystallites being determined by Ge layer thickness and annealing temperature. An essential loss of Ge from multi-layered structure after 900oC anneal and development of Ge1−x Six solid solution with x up to 0.07 in the nanocrystallites is revealed.

Исследовано влияние оптического излучения видимого диапазона на резистивное переключение в МДП-структурах ITO/ZrO2(Y)/n-Si, в том числе с наночастицами Au, встроенными в слой ZrO2(Y). Обнаружено, что зависимость ширины логического коридора резистивных состояний от интенсивности фотовозбуждения имеет пороговый характер. При увеличении интенсивности фотовозбуждения выше порогового значения наблюдалось уменьшение ширины логического коридора, предположительно, связанное с разогревом активных слоев МДП-структуры при межзонном поглощении излучения в Si-подложке. Обнаружено подавление резистивных переключений при фотовозбуждении на длине волны 650 нм (соответствующей плазмонному резонансу в наночастицах Au) за счет плазмонного оптического поглощения в наночастицах. Ключевые слова: мемристор, резистивное переключение, МДП-структуры, стабилизированный диоксид циркония, наночастицы Au, фоточувствительность.

The paper presents the results of the microstructure and morphology study of two-dimensional Ge QD arrays in a Si/Al2O3 matrix formed by annealing multilayer periodic structures with Ge nanolayers in a Si/Al2O3 matrix. The distinctive features of samples in the series are the location and thickness of the Si barrier layers between Ge and aluminium oxide matrix. X-ray reflectometry and diffractometry and transmission electron microscopy studies have shown that large Al 6 Ge 5 crystallites are formed and the multilayer structure is destroyed after annealing of the multilayer sample Al 2 O 3 /Ge without Si. It was found that the presence of Si barrier layers in multilayer Al 2 O 3 /Si/Ge structures reduces the interdiffusion of Al and Ge, but Ge 1-x Si x nanocrystallites are formed as a result of Si and Ge interdiffusion. Thus, the introduction of Si barrier layer into the Al 2 O 3 /Ge structure allowed obtaining of two-dimensional arrays of Ge 1-x Si x nanocrystallites with the penetration of Si up to 0.64.

Structures with Ge/Si nanoparticles (quantum dots) in an aluminum-oxide matrix are of interest due to the combination of two basic semiconductors and the use of a matrix with a high permittivity and strong oxygen–metal bonding. In this study, multilayer nanoperiodic structures in the form of a substrate/Al 2 O 3 /Ge/Si/Al 2 O 3 …Al 2 O 3 sequence of layers (with the period Al 2 O 3 /Ge/Si and the number of periods up to 20) are produced and then annealed at different temperatures. It is shown that, after annealing, the structures contain both Ge and Si crystalline particles, whose dimensions and number are defined by the deposited-layer thicknesses and the annealing temperature. The results obtained by different optical techniques suggest that the structures exhibit the quantum-confinement effect. This inference is supported by high-resolution microscopy.

A method is proposed for the determination of the surface density of layers in the X-ray fluorescence analysis of bilayer V−Cr systems on polikor substrates. Easy-to-make unified film layers obtained by the deposition of vanadium on polymer film substrates are used. Correction coefficients taking into account the level of intensity attenuation of the primary radiation of an X-ray tube and of the analytical line of an element of the lower layer in the upper layer, and also the enhancement of the fluorescence intensity of atoms of the upper layer by the radiation of atoms of the lower layer are calculated.

The properties of multilayer α-Si(Ge)/SiO2 nanostructures deposited onto p-Si substrates and annealed at various temperatures are investigated. The total nanolayer thickness is no larger than 300–350 nm. It is found that despite the formation of crystals in a nanolayer, the quantum-size effect does not manifest itself in the photoelectric properties of the nanolayer–substrate heterojunction in the studied temperature range of 300–900 nm. At the same time, the photocurrent efficiency (A/W) in this range becomes constant. The found results are explained by a small nanolayer thickness. When applying a sufficiently large lock bias, the electric field of the nanolayer–substrate junction reaches the outer nanolayer boundary, which abruptly decreases the surface carrier recombination. Just this recombination usually suppresses the photodetector sensitivity in the short-wavelength spectral region. The constant efficiency of the studied heterostructures in a broad spectral range makes them attractive for use in various photoelectric devices.

Structures with Ge/Si nanoparticles (quantum dots) in an alumina matrix are interesting for researchers due to the combination of two main semiconductors, as well as the use of a matrix with high dielectric permittivity and strong oxygen oxygen–metal bonding. Nanoperiodic multilayer structures in the sequence substrate/Al2O3/Ge/Si/Al2O3 . . .Al2O3 (period — Al2O3/Ge/Si, the number of periods was up to 20) annealed at different temperatures were prepared in this work. It was shown that nanocrystalline particles of both Ge and Si were observed in the structures after annealing. Nanocrystal sizes and quantity were determined by the thicknesses of deposited layers and the annealing temperatures. The results obtained by various optical techniques indicate a quantum-size effect in the structures, which is confirmed by high-resolution microscopy.

The properties of multilayer alpha-Si(Ge)/SiO(2)nanostructures deposited ontop-Si substrates and annealed at various temperatures are investigated. The total nanolayer thickness is no larger than 300-350 nm. It is found that despite the formation of crystals in a nanolayer, the quantum-size effect does not manifest itself in the photoelectric properties of the nanolayer-substrate heterojunction in the studied temperature range of 300-900 nm. At the same time, the photocurrent efficiency (A/W) in this range becomes constant. The found results are explained by a small nanolayer thickness. When applying a sufficiently large lock bias, the electric field of the nanolayer-substrate junction reaches the outer nanolayer boundary, which abruptly decreases the surface carrier recombination. Just this recombination usually suppresses the photodetector sensitivity in the short-wavelength spectral region. The constant efficiency of the studied heterostructures in a broad spectral range makes them attractive for use in various photoelectric devices.

Исследованы свойства многослойных наноструктур alpha-Si(Ge)/SiO 2 , осажденных на подложки p-Si и отожженных при разных температурах. Общая толщина нанослоя не превышала 300-350 нм. Обнаружено, что, несмотря на образование кристаллов в нанослое, в фотоэлектрических свойствах гетероперехода нанослой--подложка в исследованном диапазоне 300-900 нм не проявляется квантово-размерный эффект. В то же время эффективность фототока (А/Вт) в этом диапазоне становится постоянной. Полученные результаты мы объясняем малой толщиной нанослоя. При приложении достаточно большого запорного смещения электрическое поле перехода нанослой--подложка достигает внешней границы нанослоя, что резко уменьшает поверхностную рекомбинацию носителей. Именно эта рекомбинация обычно подавляет чувствительность фотодетекторов в коротковолновой области спектра. Постоянная в широком спектральном диапазоне эффективность исследованных гетероструктур делает их привлекательными для использования в различных фотоэлектрических приборах. Ключевые слова: многослойные наноструктуры, нанокристаллы полупроводника в диэлектрической матрице, нанослой, эффективность фототока.

We propose a new method for determining the thickness of layers in x-ray fluorescence analysis of two-layer Ti/V systems, using easily fabricated standardized film layers obtained by sputter deposition of titanium on a polymer film substrate. We have calculated correction factors taking into account the level of attenuation for the intensity of the primary emission from the x-ray tube and the analytical line for the element of the bottom layer in the top layer, and the enhancement of the fluorescence intensity for the top layer by the emission of atoms in the bottom layer.