Room- and low-temperature electroluminescence (EL) in the visible range was observed from a single layer of silicon nanocrystals in between two thin ${\mathrm{SiO}}_{\mathrm{2}}$ layers. The EL peak wavelength exhibited tunability from the red (∼800 nm) to the yellow (∼600 nm) depending on the excitation voltage. By decreasing the temperature while keeping the excitation voltage constant, an increase in EL intensity was observed together with a blueshift in EL peak position. This blueshift was much larger than that observed under optical excitation. Nonradiative Auger recombination, Coulomb charging effects, and/or the quantum-confined Stark effect are considered accountable for this behavior.

${\mathrm{Si/SiO}}_{\mathrm{2}}$ superlattices on oxidized silicon wafers were fabricated by successive cycles of silicon deposition and high-temperature thermal oxidation. Silicon films were deposited by low-pressure chemical vapor deposition at $\text{580\hspace{0.05em}°}\mathrm{C}.$ As-deposited silicon was amorphous, and it exhibited two weak photoluminescence (PL) peaks in the visible range, a stable one at $\text{≅650\hspace{0.05em}}\mathrm{nm}$ and an unstable one at 530–550 nm. By oxidation at $\text{900\hspace{0.05em}°}\mathrm{C},$ a drastic increase of the stable PL peak was observed with an initial redshift from 650 to 800–900 nm and a subsequent blueshift down to 680–700 nm. Its position and intensity depended on the oxidation time. For prolonged oxidation, PL disappeared. The observed PL is attributed to silicon crystallites passivated by oxygen. Localized states at the ${\mathrm{Si/SiO}}_{\mathrm{2}}$ interface limit the emitted wavelength. The PL peak from superlattices was at the same position as from one bilayer, while a superlinear increase in PL intensity was observed by increasing the number of bilayers.

The massive transition from in-person to remote teaching increased the impact of technology on the everyday life of the universities. Without the face-to-face component, learning and teaching became a completely different experience for students and teachers. Recording the attitudes and perceptions of the undergraduate students on the new situation became necessary for the faculties to support them effectively. This research collected quantitative and qualitative data from 336 students of all the years of studies. The students preferred in-person teaching and reported higher engagement, learning, and understanding during classroom teaching. More senior students, who had developed face-to-face ties with their colleagues before the pandemic, found it easier to continue their interactions remotely. They were interested in matching learning with the duties and needs at the particular period of their life, despite their beliefs concerning the effectiveness of in-person teaching. The first-year students found it challenging to develop relationships remotely, and they were the most frustrated. Overall, students in the first years of their studies perceived remote teaching as dissatisfactory compared to the more senior students. Similar to other publications, the respondents of this study challenged the effectiveness of remote teaching and the concomitant transition from in-person to remote social relationships.

In this work, a novel Ag nanoparticle self-assembly process based on plasma-induced two-dimensional Ostwald ripening is demonstrated. Ag nanoparticles are deposited on p-doped Si substrates using a DC magnetron sputtering process. With the assistance of O(2)/Ar plasma treatment, different sizes and patterns of Ag nanoparticles are formed, due to the Ostwald ripening. The evolution of plasma-induced nanoparticle ripening is studied and a clear increase in particle size and a decrease in particle density are observed with increasing plasma treatment. From the experiments, it is concluded that the initial nanoparticle density and the plasma gas mixture (Ar/O(2) ratio) are important factors that affect the ripening process. The proposed plasma-directed Ag nanoparticle self-assembly provides a rapid method of tailoring the nanoparticle distribution on substrates, with potential applications in the fields of solar cells, biosensors, and catalysis.

This work reports on Raman scattering of rhodamine (R6G) molecules absorbed on either randomly distributed or grating-like arrays of approximately 8-nm Ag nanoparticles developed by inert gas aggregation. Optimal growth and surface-enhanced Raman scattering (SERS) parameters have been obtained for the randomly distributed nanoparticles, while effects related to the aging of the silver nanoparticles were studied. Grating-like arrays of nanoparticles have been fabricated using line arrays templates formed either by fracture-induced structuring or by standard lithographic techniques. Grating structures fabricated by both methods exhibit an enhancement of the SERS signal, in comparison to the corresponding signal from randomly distributed Ag nanoparticles, as well as a preferential enhancement in the areas of the sharp features, and a dependence on the polarization direction of the incident exciting laser beam, with respect to the orientation of the gratings structuring. The observed spectroscopic features are consistent with a line-arrangement of hot-spots due to the self- alignment of metallic nanoparticles, induced by the grating-like templates.