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Terahertz silicon-based all-dielectric metasurfaces have attracted enormous attention for their promising applications. In practice, however, their tuning ability has been limited by the stability of silicon. Herein, we propose a new way to realize thermally tunable silicon metasurfaces in the terahertz region based on InSb film. To verify the feasibility of this method, a tunable all-dielectric metasurface absorber based on hybrid dielectric waveguide resonance is designed and demonstrated. The absorber consists of sub-wavelength silicon cylinders on the polydimethylsiloxane (PDMS) substrate, and an ultra-thin InSb film is deposited on it to achieve tunability. Meanwhile, by employing the other free-standing grating structure, the universality of this method is demonstrated. Notably, when the temperature increases from 300 to 400 K, the resonance shift in the grating structure can reach 0.091 THz, and good amplitude stability in the transmission spectrum is achieved. With advantages like fine tunability and easy fabrication, these all-dielectric metasurfaces may have great potential in THz high efficiency devices.

Плівки селеніду кадмію (CdSe) були синтезовані на скляних підкладках методами хімічного поверхневого осадження (CSD) і хімічного осадження у ванні (CBD). Для цього використано водні розчини кадмій хлориду, тіосечовини, натрій селеносульфату, тринатрійцитрату та амоній гідроксиду. Проведено теоретичні розрахунки граничних умов утворення селеніду кадмію та гідроксиду кадмію в системах кадмій-селеносульфат і кадмій-селеносульфат-цитрат-аміак. Досліджено фазовий склад, спектри оптичного пропускання та морфологію поверхні осаджених плівок CdSe. Відповідно до проведеного рентгенівського аналізу, отримані зразки плівок є однофазними і складаються із сполуки CdSe у її типовій кубічній модифікації. Поверхня плівок була суцільною, гладкою та мала невелику кількість поверхневих дефектів. Оптичне пропускання плівок CdSe зростає в досліджуваній області довжин хвиль від 340 до 900 нм. Криві пропускання мають перегини в області 650 нм, що характерно для кадмій селеніду. Значення оптичної забороненої зони плівок CdSe знаходились в діапазоні 1,82-1,88 еВ. Cadmium selenide (CdSe) films were synthesized on glass substrates via chemical surface deposition (CSD) and chemical bath deposition (CBD) methods. Aqueous solutions of cadmium chloride, thiourea, sodium selenosulfate, trisodium citrate and ammonia hydroxide were used. Theoretical calculations of the boundary conditions for the formation of cadmium selenide and cadmium hydroxide were carried out in the cadmium-selenosulfate and cadmium-selenosulfate-citrate-ammonia systems. The phase composition, optical transmission spectra and surface morphology of deposited CdSe films were investigated. According to the X-ray analysis, the film samples are single phase and consist of CdSe compound in its typical cubic modification. The film surface is solid, smooth and has a small number of surface defects. The optical transmission of CdSe films increases in the investigated wavelength area from 340 to 900 nm. The transmission curves have bends in the 650 nm region, which is typical for cadmium selenide. The optical band gap values of CdSe films are found to be in the range of 1.82-1.88 eV.

This study reports the colloidal preparation FeOx, TiO2 and FeOx-TiO2 grafted on polyethylene (PE) films leading to bacterial inactivation. A fast bacterial inactivation was attained by the FeOx-TiO2 compared to the FeOx-PE film due to the interfacial charge transfer (IFCT) FeOx to the lower-lying TiO2 trapped states. A pH-decrease was observed during bacterial inactivation due to the formation of carboxylic acids on the grafted films and the recovery to the initial pH 7 after elimination of the intermediates was followed quantitatively during bacterial inactivation. The potential on the TiO2-PE, FeOx-PE and FeOx-TiO2-PE film surfaces decreased during the bacterial inactivation concomitant with the loss of the cell wall permeability. Different mechanisms for the photo-induced E. coil inactivation for random nanoparticulate FeOx-PE and FeOx-TiO2-PE films are suggested based on the experimental observations reported in this study. During the inactivation of E. coli, the Fe-ions were seen to leach out in amounts

Cu2ZnSnS4 (CZTS) is a promising semiconductor material for photovoltaic applications, with excellent optical and electronic properties while boasting a nontoxic, inexpensive, and abundant elemental composition. Previous high-quality CZTS thin films often required either vacuum-based deposition processes or the use of organic ligands/solvents for ink formulation, which are associated with various issues regarding performance or economic feasibility. To address these issues, an alternative method for depositing CZTS thin films using an aqueous-based nanoparticle suspension is demonstrated in this work. Nanoparticles of constituent binary sulfides (CuxS and ZnS) are stabilized in an ink using tin(IV)-based, metal chalcogenide complexes such as [Sn2S6]4−. This research paper provides a systematic study of the nanoparticle synthesis and ink formulation via the enabling role of the tin chalcogenide complexing power, the deposition of high-quality CZTS thin films via spin coating and annealing under sulfur vapor atmosphere, their structural characterization in terms of nanocrystal phase, morphology, microstructure, and densification, and their resultant optoelectronic properties.

Cu2ZnSnS4 (CZTS) is a promising semiconductor material for photovoltaic applications, with excellent optical and electronic properties while boasting a nontoxic, inexpensive, and abundant elemental composition. Previous high-quality CZTS thin films often required either vacuum-based deposition processes or the use of organic ligands/solvents for ink formulation, which are associated with various issues regarding performance or economic feasibility. To address these issues, an alternative method for depositing CZTS thin films using an aqueous-based nanoparticle suspension is demonstrated in this work. Nanoparticles of constituent binary sulfides (CuxS and ZnS) are stabilized in an ink using tin(IV)-based, metal chalcogenide complexes such as [Sn2S6]4−. This research paper provides a systematic study of the nanoparticle synthesis and ink formulation via the enabling role of the tin chalcogenide complexing power, the deposition of high-quality CZTS thin films via spin coating and annealing under sulfur vapor atmosphere, their structural characterization in terms of nanocrystal phase, morphology, microstructure, and densification, and their resultant optoelectronic properties.

Coplanar conductance fluctuations in a range of device quality undoped hydrogenated amorphous silicon (a-Si:H) films prepared using different deposition systems were measured in the temperature range of 440–505 K for frequencies from 2 Hz to 3 kHz. The 1/ f α type noise spectra had two different power law dependencies, one at lower frequencies with slope α 1 close to unity and a second region at higher frequencies with slope α 2 around 0.60. The noise power density decreases with increasing temperature in the high frequency region, but only increases much less with temperature at low frequencies. The results indicate that the noise in undoped intrinsic a-Si:H films is due to two independent noise mechanisms operating simultaneously.

M.Sc. Thin film solar cells based on polycrystalline indium diselenide (CulnSe₂) and amorphous silicon (a-Si:H) are promising candidates for the efficient conversion of sunlight into useable, cheap electrical energy. However, typical device structures are rather complex and consists of semiconductor/metal contacts as well as complicated p - n and p - i - n heterojunctions. In this study, CulnSe₂ absorber layers with excellent material properties were prepared by the selenization of metallic alloys. The a-Si:H thin films were deposited by radio frequency (RF) glow discharge in vacuum. The polycrystalline and amorphous absorber layers were deposited on glass and flexible substrates. In each case, a systematic study was conducted in which all the relevant processing parameters were varied over a broad range. These studies indicated that the structural features of the substrate significantly influence the structural features of the semiconductor thin films. The flexible substrate (kapton) was characterized by the presence of ridges, which distorted the growth behavior of the films. Deposition of ln/Cu/ln metallic alloys onto Mo coated glass (kapton) resulted in discontinuous metallic alloys, which were characterized by the presence of separated elongated island structures. The structural features of the precursors were maintained in the absorber film after selenization in elemental Se vapor. The morphological features of the CulnSe₂ absorber films were also critically influenced by the reaction temperature And reaction period to Se. The structural features on a-Si:H was significantly influenced by the structural features of the particular substrate used. Atomic force microscopy (AFM) imaging in combination with statistical analysis revealed higher roughness values when the amorphous semiconductor materials were deposited onto kapton, which negatively impacts on the device properties of solar cell devices.

The electrical behavior of broken down thin films of magnesium oxide (MgO) grown on indium phosphide (InP) substrates was investigated. To our knowledge, this is the first report that identifies the Soft Break Down (SBD) conduction mode in a metal gate/high-kappa/III-V semiconductor structure. It is shown that the leakage current associated with this failure mode follows the power-law model I=aVb for both injection polarities in a voltage range that largely exceeds the one reported for SiO2. We also show that the Hard Break Down (HBD) current is remarkably high, involving significant thermal effects that are believed to be at the origin of the switching behavior exhibited by the I-V characteristics.

The oxygen adsorption effects on the Schottky barriers height measurements for thick films gas sensors prepared with undoped nanometric SnO2 particles were studied. From electrical measurements, the characteristics of the intergranular potential barriers developed at intergrains were deduced. It is shown that the determination of effective activation energies from conduction vs. 1/temperature curves is not generally a correct manner to estimate barrier heights. This is due to gas adsorption/desorption during the heating and cooling processes, the assumption of emission over the barrier as the dominant conduction mechanism, and the possible oxygen diffusion into or out of the grains. Fil: Schipani, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación En Ciencia y Tecnología de Materiales (i); Argentina. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; Argentina Fil: Aldao, Celso Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación En Ciencia y Tecnología de Materiales (i); Argentina. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; Argentina Fil: Ponce, Miguel Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación En Ciencia y Tecnología de Materiales (i); Argentina. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; Argentina

In this work, we show that surface plasmon polaritons (SPPs) at terahertz (THz) frequencies can be tuned by changing the temperature in a periodically corrugated thin film of indium antimonide (InSb) sandwiched between air and dielectric. When a THz electromagnetic wave illuminates the structure, the temperature-dependent THz SPPs can be excited, and the first and second-order modes and their cross-couplings are observed in the band structure of SPPs. Reflection dips and transmission resonances are observed in those modes. By increasing temperature, transmissions decrease and reflections increase significantly. Our studies indicate that such effects may have potential applications in designing thermally controlled THz devices.