Zinc oxide is a promising candidate for use as a sensitive layer for chemiresistive gas sensors, which has many advantages due to its physical and electrical properties, namely chemical and thermal stability, low cost, etc. This work aims to clarify the possibility of controlling the electrical, structural, and photocatalytic properties of zinc oxide films by modification with platinum during the synthesis process using a polymer precursor method, as well as by manufacturing a composite of zinc and tin oxides. Morphological, optical, electrical, and sensor properties were investigated for the obtained films. All synthesized films were characterized by a thickness of 250–380 nm and had inherent semiconductor properties with a band gap within 3.1–3.7 eV and a resistivity of 1.98 × 104 to 2.52 × 105 Ω cm. Sensoric properties of the synthesized films were tested as well, with some films demonstrating a response of 4.26 to H2 and 9.15 to NO2 at room temperature and under photoactivation by UV radiation.

Solar cell heterostructures based on PEDOT:PSS/Si heterojunction with a flat and microrelief interfaces of pyramidal and inverted pyramids type, unmodified and chemically doped PEDOT:PSS films have been fabricated. The maximum efficiency of 6.14% was obtained for solar cell heterostructures with a pyramidal type interface and doped PEDOT:PSS film, which is five times higher than for structure with a flat interface. It shown that an increase in the efficiency is occurred both due to decrease in optical losses from textured Si interface and improvement of electrical parameters of the polymer layer due to chemical doping with DMSO.

This study examines the optical properties of thin Cu (Ag)-layered structures covered with protective layers based on graphene, titanium (TiO2), or aluminium (Al2O3) oxides. The objective is to investigate the impact of these coatings on the optical behaviors of underlying metallic layers, specifically in the spectral range of excitation of surface plasmon resonances. Combining the methods of spectroreflectometry and spectro-ellipsometry was used to analyze the optical characteristics of the hybrid metal-oxide-graphene films. The study shows that graphene, due to its exceptional electrical conductivity and unique optoelectronic properties, significantly modifies the optical behavior of investigated structures. It includes notable changes in refractive and absorption indices, and optical conductivity indicating potential for enhancing light-matter interactions in plasmonic-graphene layered structures with the aim to apply as biosensor. It is important that addition of TiO2 and Al2O3 layers has also strong effects on the optical properties, which are relevant to their respective applications in the fields of optoelectronics and microelectronics. Employing the effective medium approximation and the Tauc–Lorentz model promotes deeper understanding the interplay between interband and intraband electronic transitions at the nanoscale level. It was revealed that the layer thickness of constituted materials and their individual dielectric functions together with addition of a graphene monolayer commit the significance for altering the optical properties of hybrid layered structures. The obtained results are important for the fields of plasmonics and nanotechnology, providing insights for designing sensors and devices with improved optical characteristics.

The influence of magnetic field on Psi(lambda) and Delta(lambda) dependences of Al-based plasmon-polariton photodetectors (PPPD) at different magnetic flux densities (100 and 300 mT) and magnetic field directions was investigated. It was obtained that the action of the magnetic field results in the shift of the surface plasmon resonance peak (SPR) position and a change in its intensity. Particularly, in the configuration B n i ( B and E are collinear) the noted effects were the most pronounced. Additionally, it was found that the magnetic-induced effects are sensitive to the angle of incidence, particularly they enhance with decreasing the angle of incidence. Therefore, they were the most pronounced at the smallest angle in our experiment (20 degrees). The p ossible physical mechanisms of observed phenomena are discussed. The obtained results can open up new opportunities in the design of optoelectronic sensors of the magnetic field or high-speed optical modulators.

The influence of magnetic field action on (2) and A(Z) dependencies at different magnetic flux density (100 and 300 mT) and magnetic field direction: (B) over right arrow up arrow up arrow(n) over right arrow; (B) over right arrow down arrow up arrow (n) over right arrow; (B) over right arrow perpendicular to (n) over right arrow, (B) over right arrow and (E) over right arrow are collinear, (B) over right arrow perpendicular to (n) over right arrow, (B) over right arrow and (E) over right arrow are not collinear, where is normal vector to the sample's surface, for mentioned plasmon-polariton photodetectors were investigated. It was obtained, that magnetic field action results in both blue shift and altitude of characteristic SPR peaks of the structures under investigations. It was founded that in configuration (B) over right arrow perpendicular to (n) over right arrow, (B) over right arrow and (E) over right arrow are collinear noted effect was the most pronounced. For the certain experimental configuration (B) over right arrow ,(n) over right arrow and (E) over right arrow the effect was enhanced with a decrease of the angle of incidence, and for the smallest angle in our experiment (20 degrees), it was pronounced. Possible physical mechanisms of observed phenomena are discussed. The results can open up new opportunities in the design of optoelectronic sensors of the magnetic field or high-speed optical modulators.

Impact of P and Mn incorporation into G$a$As layers on their electronic and band structures as well as magnetic and structural properties has been studied. A set of the homogenous (Ga,Mn)(P,As) layers with 8% of Mn and 0-27% of P contents of high structural perfection have been grown by low-temperature molecular-beam epitaxy. Embedding P ions into the GaAs crystal lattice leads to an increase in the band gap, while Mn impurities lead to its decrease. A significant impact of Mn interstitial impurities on the structural and magnetic properties of the films was observed. We observe an enhancement of charge density in the presence of Mn. Higher energy interband transitions involving energy band structure that includes the split-off valence band and the L-point bands remained nearly unchanged.

Impact of Bi and In incorporation into (Ga,Mn)As layers on their electronic- and band-structures as well as their magnetic and structural properties has been studied. Homogenous (In,Ga,Mn)As, (Ga,Mn)(Bi,As) and (In,Ga,Mn)(Bi,As) layers of high structural perfection have been grown by the low-temperature molecular-beam epitaxy technique. Post-growth annealing treatment of the layers results in an improvement of their structural and magnetic properties and an increase in the hole concentration in the layers. Hard-x-ray angular-resolved photoemission spectroscopy (HARPES) reveals a strongly dispersed band, crossing the Fermi energy in the highly Mn-doped layers, appearing because of high concentration of Mn-induced itinerant holes residing in the valence band. Moreover, an increased density of states near the Fermi level has been revealed in these layers and attributed to additional localized Mn states. In addition to a downward shift of the chemical potential with increasing Mn-doping, we find pronounced valence-band modifications, particularly in the case of the spin-split-off band, what disagrees with the pure impurity band model. The modulation photoreflectance spectroscopy results confirm the modifications of the valence band in the investigated layers.

The influence of the addition of Bi to the dilute ferromagnetic semiconductor (Ga,Mn)As on its electronic structure as well as on its magnetic and structural properties has been studied. Epitaxial (Ga,Mn)(Bi,As) layers of high structural perfection have been grown using low-temperature molecular-beam epitaxy. Post-growth annealing of the samples improves their structural and magnetic properties and increases the hole concentration in the layers. Hard X-ray angle-resolved photoemission spectroscopy reveals a strongly dispersing band in the Mn-doped layers, which crosses the Fermi energy and is caused by the high concentration of Mn-induced itinerant holes located in the valence band. An increased density of states near the Fermi level is attributed to additional localized Mn states. In addition to a decrease in the chemical potential with increasing Mn doping, we find significant changes in the valence band caused by the incorporation of a small atomic fraction of Bi atoms. The spin-orbit split-off band is shifted to higher binding energies, which is inconsistent with the impurity band model of the band structure in (Ga,Mn)As. Spectroscopic ellipsometry and modulation photoreflectance spectroscopy results confirm the valence band modifications in the investigated layers.

The impact of P and Mn incorporation into GaAs layers on their electronic and band structures as well as magnetic and structural properties has been studied. A set of the homogenous (Ga,Mn)(P,As) layers with 8% of Mn and 0%–27% of P contents of high structural perfection have been grown by low-temperature molecular-beam epitaxy (LT-MBE). Embedding P ions into the GaAs crystal lattice leads to an increase in the bandgap, while Mn impurities lead to its decrease. A significant impact of Mn interstitial impurities on the structural and magnetic properties of the films was observed. We observe an enhancement of charge density in the presence of Mn. Higher energy interband transitions involving energy band structure that includes the split-off valence band and the L-point bands remained nearly unchanged.

To alter the characteristics of the conductive PEDOT:PSS polymer, composite films were developed by combining it with carbon nanotubes. The utilization of these films in constructing heterostructures for photoconversion was then investigated. Composite films, comprising a blend of PEDOT:PSS and carbon nanotubes, exhibited superior conductivity in comparison to the pure polymer. Moreover, the resulting solar cell structures showcased enhanced photo conversion efficiency.

The impact of incorporating Bi into (Ga,Mn)As layers on their electronic, band structure, magnetic, and structural properties has been studied. The low-temperature molecular beam epitaxy technique was employed to grow homogeneous (Ga,Mn)(Bi,As) layers with high structural perfection. Post-growth annealing treatment resulted in improved structural and magnetic properties, as well as an increase in the hole concentration in the layers. Modulation photoreflectance spectroscopy confirmed modifications to the valence and split-off band in the (Ga,Mn)(Bi,As) layers. The experimental results are consistent with the valence band model of hole-mediated ferromagnetism in the layers. The (Ga,Mn)(Bi,As) compound combines the properties of (Ga,Mn)As and Ga(Bi,As) ternary compounds, offering the possibility of tailoring the bandgap structure to the requirements of novel device functionalities for future spintronic and photonic applications.

Impact of P and Mn incorporation into GaAs layers on their electronic- and band-structures as well as their magnetic and structural properties has been studied. A set of the homogenous (Ga,Mn)(P,As) layers with 8% of Mn and 0-32% of P contents of high structural perfection have been grown by the low-temperature molecular-beam epitaxy technique. Post-growth annealing treatment of the layers results in an improvement of their structural and magnetic properties and an increase in the hole concentration in the layers. Hard-x-ray angular-resolved photoemission spectroscopy (HARPES) reveals that a strongly dispersing band crosses the Fermi energy in the highly doped samples. This is a consequence of the high concentration of Mn-induced itinerant holes residing in the valence band of the III-V semiconductor host. We find an increased density of states near the Fermi level for higher doping levels, which one may attribute to additional localized Mn states. The spectroscopic ellipsometry (SE) results confirmed the modification of the valence band of the epitaxial layers.

The dependence of conductivity of the composite PEDOT:PSS with embedded carbon nanotubes films on the method of its preparation was investigated. Especially, a method of layer-by-layer deposition of carbon nanotubes and the method of film deposition from a mixture of PEDOT:PSS with carbon nanotubes (CNT) are compared. The electrophysical film parameters were obtained from a four-point probes measurements while optical parameters from spectroscopic ellipsometry. Our results showed that the method of layer-by-layer deposition of CNT and PEDOT:PSS allows one to obtain films with higher conductivity (approximate to 170-180 S/cm) compared to the method of depositing a film from their mixture (approximate to 62-92 S/cm).

Multiple repeated procedure of spin-coating, thermal annealing and midcycle washing of the non-conductive PSS component was developed to fabricate the multilayer PEDOT:PSS films. A 4-5 times enhancement relative to single-layer PEDOT:PSS film conductivity up to 236 S/cm was observed. An increase in conductivity results from the formation of a dense film without voids and excess of insulating PSS and closer contact between the conducting PEDOT globules. The optical properties of the multilayer PEDOT films are described well in the visible-near-IR region by combining of the Cauchy and Drude models for dielectric constants. Analysis of conductivity data from optical measurements and electrical ones suggests that the photoelectric performance of PEDOT:PSS/Si solar cells can be further improved by optimization of polymer thickness and effective optical constants.

The effect of electron irradiation on the evolution of photoluminescence and optical properties of Si-doped GaN was investigated. MOCVD grown GaN thin films were irradiated with 4 MeV electrons at different doses of 1 & sdot;107, 2.5 & sdot;107 and 1 & sdot;108 rad. It was obtained that room temperature photoluminescence as well as transmittance spectra of irradiated samples changed during long-term period after treatment. The low dose effect was observed at 107 rad. Radiation memory effect was detected. Long-term modification model based on the idea of defect diffusion is proposed. Diffusion factors of migrating components are estimated. Irradiation induced effects on the defect subsystem of gallium nitride are discussed.

In this work, two methods for fabrication of composite conductive films, consisting of single walled carbon nanotubes (SWCNTs) and PEDOT:PSS, in order to obtain films with high conductivity and transparency for their use in solar cell structures based on Si have been compared. The thickness and optical parameters of the films were determined using the spectro-ellipsometric measurements within the spectral range 0.6…5.0 eV. The electrophysical parameters were obtained from the four-point probe measurements. Our results showed that the method for deposition of SWCNTs and PEDOT:PSS in layers enables to obtain films with a much higher conductivity (220…306 S/cm) as compared to the method of applying a film from their mixture (6…209 S/cm).

The electrical characteristics and deep-level transient spectroscopy of a hybrid poly(3,4-ethylene dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/GeNCs/Si heterojunction with Ge nanoclusters grown by molecular beam epitaxy on a p-type Si(001) substrate are investigated. The heterostructure shows good rectifying J–V characteristics, the dark current exhibits an activation energies of 280 meV and 550 meV, while the reverse bias leakage current is suppressed due to the coating of Ge nanoclusters with PEDOT:PSS. We show that recombination via deep hole states close to grain boundaries can be partly suppressed by the PEDOT:PSS thin films, leading to a decrease in the saturation current and an improvement of the rectification without deterioration of forward current.

The peculiarities of optical and electrical properties of organic(clonidine)/inorganic(Si) heterojunction with plasmonic Au nanoparticles have been investigated by reflection spectra, photoelectric and current-voltage characteristics measurements. Porous nanostructured surfaces of silicon wafers were obtained by the method of selective chemical etching initiated by metal (gold) nanoparticles. Nanocomposites based on nanostructured silicon, clonidine and gold nanoparticles have been made. Two types of structure, namely, solar cells and photodiodes on the basis of such heterojunction were analysed. The reflection spectra of light confirmed the excitation of the plasmon mode in nanocomposites with gold nanoparticles. Photoelectric studies have shown an increase of the photocurrent of solar cells obtained as a result of using both nanostructured silicon and gold nanoparticles in 1.5 and 7 times, respectively. Study of the injection properties of the structures showed that the clonidine layer always facilitates the injection of current carriers, while gold nanoparticles limit the current in the case of a flat surface.

The peculiarities of optical and electrical properties of organic(clonidine)/inorganic(Si) heterojunction with plasmonic Au nanoparticles have been investigated by reflection spectra, photoelectric and current-voltage characteristics measurements. Porous nanostructured surfaces of silicon wafers were obtained by the method of selective chemical etching initiated by metal (gold) nanoparticles. Nanocomposites based on nanostructured silicon, clonidine and gold nanoparticles have been made. Two types of structure, namely, solar cells and photodiodes on the basis of such heterojunction were analysed. The reflection spectra of light confirmed the excitation of the plasmon mode in nanocomposites with gold nanoparticles. Photoelectric studies have shown an increase of the photocurrent of solar cells obtained as a result of using both nanostructured silicon and gold nanoparticles in 1.5 and 7 times, respectively. Study of the injection properties of the structures showed that the clonidine layer always facilitates the injection of current carriers, while gold nanoparticles limit the current in the case of a flat surface.

Electron-beam treatment the glass substrates for sensitive elements of SPR devices causes almost two-fold narrowing their refractometric characteristics from 0.867 down to 0.453 deg. The angular shift was also changed, which made the measuring range wider by 0.37 deg. The sensitivity of SPR devices increased by 1.7 times from 1.425 up to 2.396 deg–1 as a consequence of lowering the energy expenses during propagation of surface plasmons along the boundary “metal–air”. The reason for this lowering is related to higher surface uniformity of the gold metal film, its higher density as well as lower nano-roughness of the glass surface and the thickness of heterointerface “gold–air”. In this case, the dispersion value for unevenness heights on the surface relatively to the base line was lowered from ±18 down to ±5 nm, mean-square roughness was three-fold reduced from 4.67 down to 1.64 nm, and the thickness of heterointerface gold–air was lowered from 3.26 down to 1.37 nm. It was ascertained using X-ray reflectometry that the film density increased from 17.2 up to 19.3 g/cm3 and reached the value typical for the bulk gold. It provided the changes in the refraction index and extinction coefficient of the gold film, which was ascertained using the ellipsometric method. Thus, the performed analysis of refractometric characteristics showed that electron-beam treatment the glass substrates of sensitive elements for SPR devices is able to efficiently enhance their sensitivity and to widen the range of measured resonance SPR angles.