As one of the approaches to improve p-HEMT, we studied the effect of misorientation of GaAs substrates on the surface morphology, structure, and electrical properties of pseudomorphic heterostructures, as well as the parameters of transistors based on them. In a single technological cycle, heterostructures were formed on vicinal substrates with (100) orientation and misoriented by 2o to (110) by the method of MOCVD (MOCVD) in a single technological cycle. It has been established that on misoriented substrates, the growth of structurally consistent and stressed epitaxial layers occurs according to a layered-step mechanism with the formation of macrosteps. On vicinal substrates, the formation of monatomic growth steps was observed. The comparative characteristics of p-HEMT obtained using two types of substrates are considered. Keywords: GaAs/InGaAs/GaAlAs heterostructures, MOCVD epitaxy, p-HEMT, substrate misorientation, comparative characteristics of structures and p-HEMT based on them.

As one of the approaches to improve p-HEMT, we studied the effect of misorientation of GaAs substrates on the surface morphology, structure, and electrical properties of pseudomorphic heterostructures, as well as the parameters of transistors based on them. In a single technological cycle, heterostructures were formed on vicinal substrates with (100) orientation and misoriented by 2° to (110) by the method of MOCVD (MOCVD) in a single technological cycle. It has been established that on misoriented substrates, the growth of structurally consistent and stressed epitaxial layers occurs according to a layered-step mechanism with the formation of macrosteps. On vicinal substrates, the formation of monatomic growth steps was observed. The comparative characteristics of p-HEMT obtained using two types of substrates are considered.

In this paper, we propose a method for predicting the refractive index variation in InGaAlAs tunnel-coupled quantum wells under the action of an electric field. Complex of mathematical and experimental studies to optimize the heterosystems design forthe semiconductor modulator construction according to a planar Mach-Zehnder interferometer scheme is demonstrated.

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 compound with beta-pyrochlore structure with rare for structure type symmetry (orthorhombic, Pnma) has been prepared recently. In polycrystalline sample Rb0.95Nb1.375Mo0.625O5.79 with beta-pyrochlore structure type prepared by solid-state reaction, the diffuse reflection and transmission spectra have been studied. The spectral dependence of the photochromic effect and the temperature dependence of its kinetics have been investigated. It was found that Rb0.95Nb1.375Mo0.625O5.79 is an indirect-gap semiconductor with band gap of 3 eV. A study of the transmission spectrum and a detailed investigation of the photochromic effect made it possible to determine some characteristics of the deep impurity defect level and make a conclusion about the energy ranges in which the Fermi level can be localized in a band gap.

In this paper, we propose a method for predicting the refractive index variation in InGaAlAs tunnel-coupled quantum wells under the action of an electric field. Complex of mathematical and experimental studies to optimize the heterosystems design forthe semiconductor modulator construction according to a planar Mach--Zehnder interferometer scheme is demonstrated. Keywords: Mach--Zehnder modulator, nanoheterostructure, quantum mechanical calculations, refractive index, transmission electron microscopy, photoelectric spectroscopy.

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.

A new series of Dion-Jacobson layered perovskite compounds A’LnNaNb3O10 (A’ = Cs, Rb, H; Ln = Nd, Pr) was synthesized for the first time. Phase and chemical purity of compounds were proved using XRD, SEM, and EDX. Compounds RbNdNaNb3O10, RbPrNaNb3O10, CsNdNaNb3O10 and CsPrNaNb3O10 were synthesized using solid-state reaction, whereas HNdNaNb3O10, HPrNaNb3O10 were obtained by ion-exchange reaction. Crystal structures of solid-state reaction products were refined using the Rietveld method. The plausibility of obtained crystal structures was studied using the bond valence sum (BVS) method. The thermal behavior of compounds was established using DTA. Ion-exchange products were found to be metastable hydrates. The presence of the crystallization water was confirmed by DTA and IR spectroscopy. Optical band gap, electronegativity, valence band (EVB), and conduction band (ECB) potentials of obtained compounds were calculated from diffuse reflectance spectroscopy data. A previously proposed correlation between band gap and structural distortions was confirmed.

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.

In polycrystalline sample KNbWO6 with beta-pyrochlore structure type prepared by solid-state reaction, the diffuse reflection and transmission spectra, as well as the spectral, kinetic, and temperature dependencies of the photochromic effect, have been investigated. The energy characteristics of deep and shallow levels in KNbWO6 band gap have been determined. A model explaining the effect of temperature on the behavior of bleaching kinetics in the photochromic effect was suggested.

Abstract The effect of neutron irradiation on the photosensitivity of the InAs/GaAs quantum dots has been investigated. It was shown that after neutron irradiation with a fluence of 1.5×1015 cm-2 the photosensitivity at the room temperature has been decreased at 3 times, whereas the shape of the photosensitivity’s temperature dependence didn’t reveal any visible changes, despite an appearance of defects in quantum dot layer. The effect was explained by the difficulty of a motion of photoexcited carriers in quantum dot layer to the recombination centres arised after irradiation.

AbstractOn the basis of a comprehensive study of the structural and electronic properties of InAs/GaAs quantum dots grown by vapor-phase epitaxy at atmospheric pressure, a structural model of the quantum dots as three truncated pyramids adjoined at their bases is chosen. The model takes into account the diffusive smearing of the composition near the base and lateral surface as well as the segregation of indium near the vertex. It is established that the wave functions of charge carriers in the ground state are localized in a comparatively small region of the quantum dot near its vertex.

On the basis of a comprehensive study of the structural and electronic properties of InAs/GaAs quantum dots grown by vapor-phase epitaxy at atmospheric pressure, a structural model of the quantum dots as three truncated pyramids adjoined at their bases is chosen. The model takes into account the diffusive smearing of the composition near the base and lateral surface as well as the segregation of indium near the vertex. It is established that the wave functions of charge carriers in the ground state are localized in a comparatively small region of the quantum dot near its vertex.

AbstractA comparative study of the effect of pulsed γ-neutron irradiation on the photosensitivity spectra of Si p – n photodiodes with active layers based on self-assembled GeSi nanoisland arrays and Ge epitaxial layers is performed. The irradiation of photodiodes with GeSi nanoislands is found to not lead to photosensitivity degradation in the spectral region of interband optical absorption in nanoislands (wavelength range of 1.1–1.7 μm). At the same time, a steady decrease in the intrinsic photosensitivity of Si and the photosensitivity of photodiodes based on Ge epitaxial layers with an increase in irradiation dose is observed. This effect is attributed to the accumulation of radiation-induced defects in the Si matrix and deep in Ge epitaxial layers, respectively.

We report on the investigation of the photoconductivity (PC) in the yttria stabilized zirconia (YSZ) films with embedded Au nanoclusters (NCs). A peak in the PC spectrum corresponding to the plasmon optical absorption resonance in the Au NCs was observed. The temperature dependence of PC near 300 K obeyed Mott law. In this case, the PC was attributed to the heating of the YSZ matrix due to the plasmon optical absorption in the Au NCs (bolometric effect). Near 77 K, the PC did not depend on temperature and was attributed to plasmon-assisted electron transport between the NCs via the vacancy α-band in YSZ.

A comparative study of the effect of pulsed γ-neutron irradiation on the photosensitivity spectra of Si p–n photodiodes with active layers based on self-assembled GeSi nanoisland arrays and Ge epitaxial layers is performed. The irradiation of photodiodes with GeSi nanoislands is found to not lead to photosensitivity degradation in the spectral region of interband optical absorption in nanoislands (wavelength range of 1.1–1.7 μm). At the same time, a steady decrease in the intrinsic photosensitivity of Si and the photosensitivity of photodiodes based on Ge epitaxial layers with an increase in irradiation dose is observed. This effect is attributed to the accumulation of radiation-induced defects in the Si matrix and deep in Ge epitaxial layers, respectively.

Заращивание массива самоорганизованных квантовых точек InAs/GaAs слоем квантовой ямы InGaAs приводит к увеличению их размера за счет обогащения области вблизи вершины квантовых точек индием, что уменьшает энергию основного оптического перехода в квантовых точках на 50 мэВ и смещает волновую функцию дырки по направлению к вершине квантовой точки. DOI: 10.21883/FTP.2017.11.45088.02

We report on the experimental observation of photoconductivity (PC) in ultrathin (≈ 40 nm thick) ZrO2(Y) films with single layered arrays of Au nanoparticles (NPs) of 1 to 3 nm in diameter. The samples were prepared by the deposition of islanded Au films of ∼1 nm in thickness sandwiched between two ZrO2(Y) layers by Magnetron Sputtering followed by annealing. The effect of PC was attributed to the photoexcitation of the collective plasmon oscillations in dense Au NP arrays. The temperature dependencies and kinetics of PC have been studied. At 300 K, the PC has been found to originate mainly from heating of ZrO2(Y) due to plasmon optical absorption in Au NPs (the bolometric effect). At 77 K, the photoresponse has been attributed to plasmon-assisted electron transport between NPs via the vacancy α-band in ZrO2(Y) barriers.

The spatial distribution of photocurrent in the plane of a Si-based p + – n junction with embedded self-assembled Ge x Si 1– x ( x ≈ 0.35) nanoislands is studied by scanning near-field optical microscopy with local photoexcitation by a microscope probe at an emission wavelength of 1310 nm (larger than the intrinsicphotosensitivity red edge for Si). Inhomogeneities related to interband optical absorption in separate GeSi nanoislands are observed in the photocurrent images (maps of the spatial distribution of the photocurrent in the input-window plane of the p + – n photodiodes). The results of this study demonstrate the possibility of visualizing individual GeSi nanoislands in images of the photocurrent with a spatial resolution of ~100 nm.