Влияние никеля на время жизни носителей заряда в кремниевых солнечных элементах

It has been shown experimentally that nickel clusters on the surface of a silicon sample contain a large amount of oxygen and recombination impurities - Cu, Fe, Cr, which shows good gettering properties of clusters. The optimum temperature of nickel diffusion into silicon is determined - Т=800-850 ° С. Doping with impurity nickel atoms with the formation of clusters makes it possible to increase the lifetime of nonequilibrium charge carriers in the base of a solar cell by up to 2 times, while the formation of a nickel-enriched region in the face layer is more efficient. It is shown that the effect of additional doping with nickel weakly depends on the sequence of the processes of nickel diffusion and the creation of a working p–n-junction.

Germanium Nanowires as Sensing Devices: Modelization of Electrical Properties

In this paper, we model the electrical properties of germanium nanowires with a particular focus on physical mechanisms of electrical molecular sensing. We use the Tibercad software to solve the drift-diffusion equations in 3D and we validate the model against experimental data, considering a p-doped nanowire with surface traps. We simulate three different types of interactions: (1) Passivation of surface traps; (2) Additional surface charges; (3) Charge transfer from molecules to nanowires. By analyzing simulated I–V characteristics, we observe that: (i) the largest change in current occurs with negative charges on the surfaces; (ii) charge transfer provides relevant current changes only for very high values of additional doping; (iii) for certain values of additional n-doping ambipolar currents could be obtained. The results of these simulations highlight the complexity of the molecular sensing mechanism in nanowires, that depends not only on the NW parameters but also on the properties of the molecules. We expect that these findings will be valuable to extend the knowledge of molecular sensing by germanium nanowires, a fundamental step to develop novel sensors based on these nanostructures.

INTERMETALLIC COMPOUND AlxTi – ARE PROMISING MATERIAL FOR HIGH ELEVATED TEMPERATURES (review) Part 2. The mechanical properties of the intermetallic Al2Ti compound and the effect of alloying

Intermetallide alloys based on the Al2Ti compound are the most promising heat-resistant materials for future energy plants.The review examines the mechanical properties of the Al2Ti Intermetalide, two-phase alloys based on it and the doped niobium alloy. For use at temperatures of up to 950 °С, alloys with phase composition r-Al2Ti + γ-TiAl and platemicrostructure with additional doping of refractory elements are of interest.

Influence of electrically neutral nickel atoms on electrical and recombination parameters of silicon

The results of this study show that creation of clusters from impurity nickel atoms almost completely suppresses generation of thermal donors within the temperature range 450 to 1200 °C. The composition of these clusters was determined using the technique of energy dispersive X-ray spectroscopy, which revealed that the typical cluster consists of silicon atoms (65%), nickel atoms (15%) and oxygen atoms (19%). Based on the experimental results, the authors have suggested that the nickel atoms intensively perform the role of getter for oxygen atoms in the course of clusterization. It was shown that the additional doping of silicon with nickel at T = 1100…1200 °C enables to ensure a sufficiently high thermal stability of its electrical parameters within a wide temperature range.

Influence of nitrogen ion implantation on the electrophysical properties of the gate dielectric of power MOSFETs

Power MOS-transistors with vertical structure are investigated. Additionally, in some devices, ion implantation of nitrogen with energies of 20 and 40 keV was carried out in a dose range of 1 ⋅1013–5 ⋅ 1014 cm –2 through a sacrificial oxide 20 nm thick. For one group of wafers, rapid thermal annealing was first carried out, then oxide removal (forward order), for the other group – in the opposite sequence (reverse order). It was found that with the additional doping of nitrogen ions in doses of 1⋅1013–5 ⋅ 1013 cm –2 with energy of 20 keV, an increasing of gate dielectric charge to breakdown for both types of annealing is observed. The maximum effect occurred for the samples at a dose of nitrogen ions of 1⋅1013 cm –2 with the forward heat treatment order. This is due to the interaction of nitrogen atoms with dangling bonds of the Si – SiO2 interface during annealing, as a result of which strong chemical bonds are formed that prevent charge accumulation on the surface of the Si – SiO2 interface. It is assumed that the main contribution to the gate leakage current is made by the tunneling of charge carriers through traps.

High-temperature stable piezoelectric transducers using epitaxially grown electrodes

Piezoelectric resonators are of great importance for application in high-precision transducers. However, at elevated temperatures, the degradation of commonly used metal electrodes may affect the performance of oxide electrodes of piezoelectric transducers; with sufficiently high electrical conductivity they are expected to overcome this deficit. In the latter case, the stable operation of piezoelectric transducers could be further enhanced if the resonator and electrodes would consist of identical or at least very similar materials; thus, nearly monolithic resonators are created. The present work focuses on two major aspects: the growth of high-quality langasite (La3Ga5SiO14; LGS) and doped LGS thin-film electrode layers by pulsed laser ablation and the characterization of the developed resonator devices. To obtain epitaxial films of the correct stoichiometry, the deposition on heated substrates is performed in oxygen atmosphere in the range from 10−3 to 10 Pa. Another requirement for adjusting the stoichiometry is an increased Ga content in the sputter targets with respect to LGS to account for Ga evaporation during film deposition. Additional doping with Sr increases the electrode film conductivity; thus combined with the use of low-conductivity single-crystalline catangasite (Ca3TaGa3Si2O14; CTGS) substrates the ratio between the electrical conductivities of the substrate and the film is increased, enabling the preparation of nearly monolithic resonators. The properties of these nearly monolithic resonators are characterized in the temperature range of 600 to 1000 ∘C and compared to those of CTGS resonator blanks without electrodes. Particular attention is paid to the reproducibility of resonator properties, the electrode orientation and the quality factor. The created nearly monolithic resonator demonstrates stable operation in the temperature range from 600 to 1000 ∘C.

Characterisation of osteogenic and vascular responses of hMSCs to Ti-Co doped phosphate glass microspheres using a microfluidic perfusion platform

Using microspherical scaffolds as building blocks to repair bone defects of specific size and shape has been proposed as a tissue engineering strategy. Here, phosphate glass (PG) microcarriers doped with 5 mol % TiO2 and either 0 mol % CoO (CoO 0%) or 2 mol % CoO (CoO 2%) were investigated for their ability to support osteogenic and vascular responses of human mesenchymal stem cells (hMSCs). Together with standard culture techniques, cell-material interactions were studied using a novel perfusion microfluidic bioreactor that enabled cell culture on microspheres, along with automated processing and screening of culture variables. While titanium doping was found to support hMSCs expansion and differentiation, as well as endothelial cell-derived vessel formation, additional doping with cobalt did not improve the functionality of the microspheres. Furthermore, the microfluidic bioreactor enabled screening of culture parameters for cell culture on microspheres that could be potentially translated to a scaled-up system for tissue-engineered bone manufacturing.

First-principles investigations of the stability and electronic properties of fluorinated Janus MoSSe monolayer

The stability and electronic structures of fluorinated Janus MoSSe (MoSSe-Fx, x = 0–16) were investigated by the first-principles method. Energetically, the Setop site of Janus MoSSe is the most favorable site for F-adsorption. Based on the adsorption, binding and formation energy analysis, it seems the fluorinated Janus MoSSe is stable. The analysis of the electronic density distribution and orbital hybrid shows that the fluorinated Janus MoSSe forms stable structure as well. Then, the electronic structure and work function change with the concentration of F atoms analyzed. With the increase of adsorbed F atoms, the bandgap of Janus MoSSe-Fx decreases from 1.456 (pristine case, [Formula: see text]) to 1.073[Formula: see text]eV (semi-fluorinated case, [Formula: see text]), and changes from direct to indirect bandgap semiconductor. It is noteworthy that there are some additional doping levels near the valence band after F adsorbed, which originated from the F 2[Formula: see text] doping states. The charge population analysis shows that electrons transfer was from Se to F atoms. It is worth noting that the charge on F atom (MoSSe-F16) is two times more than Se atoms in pristine Janus MoSSe (MoSSe-F0). As a result, the built-in electric field pointed from Mo to F atoms is enhanced, resulting in the tremendous increase of the work function for fluorinated Janus MoSSe. The work function changes from 5.22[Formula: see text]eV ([Formula: see text]) in pristine case to 8.30[Formula: see text]eV after semi-fluorinated ([Formula: see text]). Therefore, due to the adjustable work function and built-in electric field, the fluorinated Janus MoSSe monolayer shows better properties for applications in the piezoelectric device, optoelectronic device or photocatalyst.