The films fabricated by heat treatment at 600–800°C of a material based on sp carbon synthesized by polyvinylidene fluoride dehydrofluorination are studied. The structure of the films is studied by scanning electron microscopy, X-ray diffraction, infrared spectroscopy, and Raman spectroscopy. For the electron emission of the films, the turn-on field is 0.3–1.5 V/μm. The influence of the structure of the polyene and graphite phases having formed upon annealing on the emission characteristics of the material is considered. The emission is found to be caused by field emission and thermionic mechanisms.

The coatings comprised of the nanodiamond-based and amorphous-carbon-based phases (a-C:ND coatings) are investigated. The a-C:ND coatings were synthesized by chemical vapor deposition in the arc discharge plasma (by plasma chemical deposition) at various concentrations of Ar/H2/CH4. Raman spectroscopy showed that, apart from the diamond substructure, studied coatings contain amorphous-carbon-based and polyene-based phases, while diamond phase is passivated by hydrogen to different degrees. The interplay between the deposition parameters and materials' structure is analysed. It was shown that the ordering of the amorphous substructure and the formation of the phase boundaries affect the electron transport and secondary electron emission properties. The subject of the investigation of the true secondary electron spectra for the analysis of the nanostructured carbon materials is analysed. It was shown that the change of the polyene fraction in the structure of the samples leads to the variation of the ratio of field emission and thermionic emission. The influence of the structure and phase composition of the samples on their electron emission properties is investigated. In particular, their effect on the turn on-field, which value varied in the 9-18 V/μm range for the studied samples, is analysed.

The coatings comprised of the nanodiamond-based and amorphous-carbon-based phases (a-C : ND coatings) are investigated. The a-C : ND coatings were synthesized by chemical vapor deposition in the arc discharge plasma (by plasma chemical deposition) at various concentrations of Ar/H 2 /CH 4 . Raman spectroscopy showed that, apart from the diamond substructure, studied coatings contain amorphous-carbon-based and polyene-based phases, while diamond phase is passivated by hydrogen to different degrees. The interplay between the deposition parameters and materials' structure is analysed. It was shown that the ordering of the amorphous substructure and the formation of the phase boundaries affect the electron transport and secondary electron emission properties. The subject of the investigation of the true secondary electron spectra for the analysis of the nanostructured carbon materials is analysed. It was shown that the change of the polyene fraction in the structure of the samples leads to the variation of the ratio of field emission and thermionic emission. The influence of the structure and phase composition of the samples on their electron emission properties is investigated. In particular, their effect on the turn on field, which value varied in the 9-18 V/μm range for the studied samples, is analysed. Keywords: nanodiamond composites, polyene-like materials, electron transport, hydrogen passivation, turn-on field.

Представлены результаты исследования аморфных углеродных покрытий с инкапсулированными серебряными наночастицами (a-C : Ag). Методом просвечивающей электронной микроскопии показано, что введение низкоэнергетического (100-300 eV) ионного ассистирования в процесс импульсно-плазменного осаждения может в различных случаях привести как к унимодальному, так и к бимодальному распределению серебряных включений по размерам. Установлено, что характер распределения определяется мощностью импульсно-плазменного источника. Рассмотрено влияние вариации потока осаждающихся частиц на процесс ионно-индуцированной поверхностной диффузии на поверхности покрытий. Показано, что данный процесс в совокупности с ионно-индуцированным формированием центров зародышеобразования оказывает влияние на характер распределения серебряных включений по размерам. С помощью спектроскопии характеристических потерь энергии электронов установлено, что изменение поверхностной концентрации серебряных наночастиц коррелирует с соотношением sp2- и sp3-гибридизованных атомов углерода. Ключевые слова:импульсно-плазменное напыление; ионная стимуляция; углерод-серебряный композит; бимодальное распределение частиц; соотношение sp2- и sp3-гибридизованного углерода.

Amorphous carbon coatings with encapsulated silver nanoparticles (a-C:Ag) are studied. It is shown by transmission electron microscopy that the introduction of low-energy (100–300 eV) ion assistance into the process of pulse-plasma deposition in different cases lead to either the unimodal or bimodal size distributions of silver inclusions. It is established that the type of distribution is determined by the power of the pulse-plasma source. The effect of the variation of the flow of deposited particles on the process of ion induced surface diffusion over the coating surface is analyzed. It is shown that this process along with the ion induced formation of nucleation sites affects the nature of size distribution of silver inclusions. It is found using the spectroscopy of characteristic electron energy losses that the change in the surface concentration of silver nanoparticles correlates with the ratio of sp 2 and sp 3 hybridized carbon atoms.

The technique of ion-plasma pulse-arc sputtering of graphite in a methane atmosphere has been employed to produce carbon films with different phase composition. Raman spectroscopy and transmission electron microscopy showed that increase of methane concentration in the vacuum deposition chamber leads to the growth of fraction containing sp-hybridized chains. In the investigated films structure, resistivity strongly correlates with the content of sp-hybridized carbon.

Carbon films with different extents of sp hybridization have been grown by ion–plasma pulsed arc sputtering of graphite in a methane atmosphere. Using Raman scattering and transmission electron microscopy data, it has been shown that the content of the phase including carbon chains with sp hybridization grows with increasing methane concentration in the working volume. The resistivity of carbon films correlates well with the fraction of sp-hybridized carbon in the films.

Thin carbon films prepared by pulsed plasma ion-assisted deposition of graphite in an atmosphere of a mixture of argon and nitrogen are studied. The results of characteristic electron energy loss spectroscopy and electron diffraction indicate the increase in the graphite component with increasing ion assistance energy. The use of ion assistance during the film deposition makes it possible to control their resistivity by changing it from 10 5 to 10 2 Ω cm.

In the paper, thin carbon films deposited by pulse-plasma ion-assisted sputtering of graphite in argon-nitrogen gas mixture are discussed. The EELS and electron diffraction showed the graphite phase enlargement with the ion assistance energy increase. Application of ion assistance during the deposition process made it possible to control the films specific resistivity, altering it from 10^5 to 10^2 Ohm⋅cm.

Изучены эффекты зарядки диэлектрических мишеней при облучении электронами средних энергий в сканирующем электронном микроскопе. Установлены существенные различия кинетики зарядки для исходных образцов и образцов, предварительно облученных электронами и ионами. Эти различия объясняются радиационно-стимулированным дефектообразованием в образцах Al2O3 (сапфир) и SiO2, имеющим, однако, различную природу. Показана роль модификации структуры поверхности и изменения электрофизических характеристик поверхности, в частности эффекта растекания зарядов. Обнаружены критические значения дозы облучения как ионами Ar+, так и электронами, при которых начинается активное дефектообразование в диэлектрических мишенях, а также критические значения внутренних полей зарядов, вносящих существенный вклад во временные характеристики зарядки Al2O3 и SiO2. Работа выполнена при финансовой поддержке РФФИ (грант N 15-02-07819а). DOI: 10.21883/FTT.2017.08.44749.460

The dependence of secondary electron emission coefficient σ on the angle α of primary electron incidence onto single crystals of metals with different crystalline lattice has been studied for undisturbed surface and for disturbed one by sputtering. We used the single crystals of Cu (fcc), Mo (bcc), Zn (hcp) and Ni4Mo (tetragonal lattice). It was shown that the coefficient σ is smaller for the disturbed surface, than for initial one due to absorption of secondary and scattered electrons by the lateral surfaces of hills and cones which are formed as a result of sputtering. For the initial surfaces (of Cu, Mo and Ni4Mo) the maxima of σ(α) in the low-index directions of the crystal lattice arise as a result of primary and secondary electron scattering on the atoms in open channels. At the same time, for the preliminary highly oxidized single crystal surface (of Zn) the minimum of σ in the direction of open channel was observed. The last can be explained by a reduction of work function of surface, and increase in penetration depth of electrons in open channel and by a rise of electron-phonon interaction. Angular dependences of secondary electron emission for a sputtered surface have a more complicated structure with the additional maxima and minima caused by interaction of secondary and scattered electrons with a cone-shaped relief.

The effects of charging of dielectric targets irradiated with moderate-energy electrons in a scanning electron microscope are examined. Considerable differences in the kinetics of charging of the reference samples and the samples preirradiated with ions and electrons are reported. These differences are attributed to the processes of radiation-induced defect formation in Al2O3 (sapphire) and SiO2 that are, however, dissimilar in nature. The contributions of surface structure modification and changes in the electrophysical parameters of the surface (specifically, the charge spreading effect) are revealed. Critical doses of irradiation with Ar+ ions and electrons inducing active defect formation in dielectric targets and critical values of internal charge fields producing a significant contribution to the temporal parameters of Al2O3 and SiO2 charging are determined.

Lightning inside the chamber of a scanning electron microscope (SEM), caused by electrons being scattering from a sample (and parts of the chamber), is observed and analyzed. These electrons generate the luminescence in a Thornly–Everhart collector. This parasitic effect (artifact) must be considered and eliminated in all experiments with the cathodoluminescent (CL) mode of SEM. A new technique for measuring surface potential on dielectric samples is proposed. It is based on variations in the CL signal during electron irradiation of a sample in SEM.

The difference between the forms and positions of the maximum of the energy spectrum of secondary 63Cu+ ions emitted from the (100) face of a Cu single crystal in close-packed <110> directions and between them at different target temperatures is revealed. For a sample at room temperature, it is established that the most probable ion energy E max and the width h of the energy spectra at half-height increase with the polar emission angle, θ, measured from the normal to the surface. The opposite tendency, namely, a decrease in E max with increasing θ, is obtained for ions emitted from a single crystal heated to several hundred degrees Celsius. Based on modern models of secondary ion emission, the observed regularities, which must be taken into account in the theoretical description of the process and in the practical application of secondary ions in mass spectroscopy, are discussed.

The change in the structure and composition of deformed regions hidden beneath the surface of samples are studied experimentally upon their identification by the method of successive processes of polishing and sputtering. Two present-day steel coins coated with different binary alloys, a 1-ruble coin (coated with the alloy Ni1%Fe) and a 50-kopeck coin (coated with the tompak alloy Cu10%Zn), and also a 5-kopeck coin minted in 1990 consisting of brass L60 are used as the samples. It is found that a change in the surface structure (different for the studied coins) and an increase in the light-component concentration take place in the region of increased deformation by pressing due to its diffusion to the side of greater deformation. The obtained results can be used for improving the means of determining hidden deformed regions using sputtering and stage-like analysis of the surface composition.

The present paper is devoted to experimental investigation of electron-stimulated desorption from a single-crystal sapphire surface. Using Auger electron spectroscopy metallization of the sapphire surface, the character of which is dependent on the electron beam parameters, is observed under low-energy electron bombardment,. Using atomic-force microscopy, images of metal island films with a diameter of 50–100 nm are obtained.