Hysteresis effect during reactive sputtering

In this work, we studied the effect of constant parameters of the sputtering system on the width of the hysteresis loop during reactive sputtering. The sticking coefficient of the reactive gas to the surface, the chamber pumping speed, the target area, etc. are taken as parameters. The comparative study was carried out by numerical solution of systems of algebraic equations describing the chemisorption and physicochemical models of metal target reactive sputtering in a single reactive gas. The calculations were performed for sputtering a tantalum target in an Ar + O2 mixture. The studied dependences were non-linear in all cases.

Physicochemical models: source-tailored or generic?

ABSTRACT Physicochemical models can be powerful tools to trace the chemical evolution of a protostellar system and allow to constrain its physical conditions at formation. The aim of this work is to assess whether source-tailored modelling is needed to explain the observed molecular abundances around young, low-mass protostars or if, and to what extent, generic models can improve our understanding of the chemistry in the earliest stages of star formation. The physical conditions and the abundances of simple, most abundant molecules based on three models are compared. After establishing the discrepancies between the calculated chemical output, the calculations are redone with the same chemical model for all three sets of physical input parameters. With the differences arising from the chemical models eliminated, the output is compared based on the influence of the physical model. Results suggest that the impact of the chemical model is small compared to the influence of the physical conditions, with considered time-scales having the most drastic effect. Source-tailored models may be simpler by design; however, likely do not sufficiently constrain the physical and chemical parameters within the global picture of star-forming regions. Generic models with more comprehensive physics may not provide the optimal match to observations of a particular protostellar system, but allow a source to be studied in perspective of other star-forming regions.

Problem of the modeling the filaments after laser-induced breakdown the matter

The problems of the appearance of laser-induced filamets in the matter are discussed. A detailed analysis of the formation of such structures in various media: from air to silicon carbide, is represented. The influence of the spectral composition, the number of pulses and the duration of the irradiation and the medium on the geometric dimensions of the resulting structures and on their phase states is shown. In this case, the sizes of filaments vary from several hundred nanometers for silicon carbide to several hundred meters for air. The emission spectrum is continuous, and resembles the Cherenkov radiation. Therefore, the idea was developed that the radiation of filaments and the radiation of Cherenkov are of the same nature. The problems of the mechanisms of the formation of laser-induced destruction cascades in silicon carbide are discussed. To explain the experimental results, we used modified Rayleigh models (diffraction stratification of the laser beam and critical sizes of nanovoids), physicochemical models for determining critical energy values for the corresponding processes, and models for optically-induced Cherenkov radiation.

Туннельная эмиссия электронов из наноструктурированных кремниевых катодных матриц с фтор-углеродным покрытием

Variations of the morphology and field-emission properties of surface-structured n - and p -type silicon wafers have been studied. The silicon surface has been structured by etching in a fluorine–carbon plasma and depositing subnanodimensional island carbon masks. It has been shown that surface structuring in a fluorine–carbon plasma makes it possible to reach desired field-emission currents in electric fields of different strengths. Physicochemical models of field emission mechanisms and models of destruction of surface-modified multipoint silicon array cathodes have been considered.

Albite thermal barrier and alkaline granite-syenitenepheline-syenite rock association (series, formation, assemblage)

The object of research. The main goal of the work was to resolve the problem of the existence of rock associations: alkaline granites–syenites–nepheline syenites, which is found on all continents among ancient platforms and stabilized folded regions of different ages. Beginning with 70-th. of the past century, the absolute majority of the world's petrologists do not allow the possibility of a comagmatic formation of such a rock association due to the presence of a thermal albite “barrier” between phonolitic and rhyolitic melts. Materials and methods. Numerous data were used on the Ilimaussak alkaline massif from southern Greenland as the most thoroughly studied and widely known to petrologists around the world. The main methods of research were the development of physicochemical models of phase transitions and the construction of state diagrams. Results. Earlier, thanks to the author's work in the field of constructing state diagrams, the possibility of “destruction of thermal barriers” was demonstrated at the appearance of alumosilicate melts of biotite, amphibole, analcime and other minerals on the liquidus. The developed physicochemical models of phase transitions for specific rock associations of the Ilimaussak massif allowed us to prove the possibility of a comagmatic transition from nepheline-modal syenites to quartz-modal alkaline granites. Conclusions. The validity (correctness) of the theoretical constructs is proved by an almost perfect coincidence of the model and natural trends of the rock associations. This requires a certain composition of the initial melt and the optimal fluid pressure.