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We have examined the effect of focused nanosecond laser pulses on the formation and tribological properties of microstructures in the form of a matrix of craters produced in a – C : H : Si : O diamond-like films (DLFs), both undoped and doped with tungsten. The studies are performed by scanning probe microscopy (SPM) using SPM probes of standard design with a tip and probes without a tip (tipless-type probes). A special procedure is developed for assessing the wettability (contact angle) of individual sections of the laser-induced microstructure by the local adhesion force. According to estimates, the material inside the crater becomes softer and more hydrophobic as a result of laser irradiation. This is manifested to the greatest extent in tungsten-doped DLFs, where the crater walls are arranged like terraces formed by ‘nanoflakes’, i.e. grains of the substance. Scanning of microstructures with a tipless probe in the regime of lateral force microscopy demonstrates a decrease in friction in the crater area.

The influence of titanium doping of diamond-like nanocomposite films a-C:H,Si:O on the process of their structuring by the technique of bias-induced probe nanolithography of the scanning probe microscope (SPM) was studied. It has been found that titanium doping suppresses formation of dendritic-like structures that grow in undoped a-C:H,Si:O films at relative humidity above 50%. Instead of dendritic-like nanostructures, hill-like protrusions arise. At the same time, a decrease in the electrical conductivity and an increase in the friction forces in the modified region are close to those on films without metal. The mechanisms of the observed effects are discussed.

Changes in properties of graphene grown by chemical vapor deposition (CVD) with water adsorbate removal from the graphene–SiO2/Si substrate interface using an organic material, i.e., acetone, are studied. It is found that acetone vapor suppresses grapheme structuring under low-intensity nanosecond laser radiation (wavelength λ = 532 nm). It is found that the electron work function in graphene decreases by ∼0.2 eV, which is presumably due to a decrease in the water adsorbate layer thickness at the mentioned interface.

We have studied the effect that the substitution of an organic substance (ethanol) for water adsorbate on a CVD graphene–SiO2/Si interface has on the laser-induced modification of graphene and graphene structures on the SiO2 film. Scanning probe microscopy has been used to analyse changes in the electronic properties of graphene structures on a hydrophilic substrate in the presence of ethanol and as a result of a laser-induced spatial redistribution of a water–alcohol adsorbate on the interface. It has been demonstrated experimentally that ethanol substitution for water adsorbate leads to an increase in the surface potential of the graphene, which is equivalent to a reduction in its work function with respect to the original level under normal conditions at a relative humidity of air from 30% to 60%. In the laser irradiation zone, we observe an additional increase in surface potential by 30–50 mV. Thus, ethanol makes it possible to tune the laser-induced electronic properties of graphene on a substrate. In addition, it has been shown that the intercalation of ethanol molecules leads to severe temporal instability of the physical properties of graphene structures produced by local laser irradiation. We have demonstrated the possibility of information 'rewriting' by low-intensity laser pulses in microregions with a changed surface potential in the presence of ethanol.

Dendrite-like structure growth in ultrathin diamond-like nanocomposite a-C:H,Si:O films have been studied in the course of electrically induced scanning probe lithography in the presence of a water adsorbate. The threshold magnitude of the electrical action is about 2 V, which is close to the potential of water electrolysis—1.23 V. The environment humidity crucially influences the growth of dendrite-like structures. Therefore, at a relative humidity of ~20%, hill-like protrusions occur, whereas, at a relative humidity of ~40%, some radially directed protrusions (ridges) appear and, at a relative humidity of ~60%, some branches arise from the ridges. It is established that the surface of the dendrite-like nanostructures is characterized by a higher friction force in the nanoscale when compared with the initial material under AFM testing. The growth mechanism and friction properties of the dendrite-like nanostructures are discussed.

The role of the electric field during manipulations with diamond nanoparticles on a silicon substrate by a scanning probe microscope (SPM) tip is studied. It is found that the attractive force appearing in the contact between nanodiamond and an electrically charged tip is sufficient to detach and displace a chosen nanoparticle from initial to goal position under moderate mechanical stresses of the probe to nanoparticle. The problem of the control of the tip motion trajectory during manipulations is solved by visualizing the tip trace of the sample surface. The results obtained will be used for precision positioning of single-photon emitters based on luminescent nanodiamonds in microcavities.

A complex technique of scanning probe microscopy/spectroscopy (SPM/SPS) based on the microscopy of lateral forces and registration of a local electrical conductivity in combination with measurements of the microrelief has been developed for studies of laser-graphitized carbon microstructures. The method includes multiple direct and reverse probe scanning with the subsequent correction of the map position, their pixel-by-pixel subtraction and averaging, and a statistical processing of resulting data arrays concerning the distribution of lateral forces (friction forces). In addition, based on the measurements of currentvoltage (I–V) characteristics, a distribution of the electrical conductivity is built in the probe-sample circuit. Carbon structures based on hydrogenated diamond-like films of a-C:H type, which were deposited onto Si substrates, are used as the objects for studies. A local graphitization of the surface has been carried out by the irradiation of the films with an excimer KrF laser according to a preset microscopic pattern. Based on the resulting data, it is found that the reaction of the lateral forces (friction forces) in the laser-graphitized region is reversed to the temperature variations: when the temperature increases (from room to ∼120°C), the distribution of the friction forces shifts towards higher values and returns practically to the initial values when the temperature decreases to the initial level, which proves the influence of a water adsorbate on the friction properties of laser-graphitized regions on the film surface. It is also found that the laser-graphitized region is structurally inhomogeneous, which is proven by a decrease in the electrical conductivity from the center to the periphery.

Surface modification of conductive boron-doped diamond has been conducted using the electrical field of the probe of a scanning probe microscope (SPM) at varying relative humidity (RH) of the ambient environment. It has been found that, under the action of positive polarity pulses applied to the sample via a grounded SPM probe, the sample material undergoes modification. The modification pattern depends on atmospheric RH: low (up to 32%) and high humidity values (above 35%) lead to the formation of cavities and protrusions, respectively. It has been found that the resulting protrusions exhibit temporary instability; that is, a protrusion is partially transformed into an array of nanoobjects. The mechanism of modification of boron-doped diamond–local anodic oxidation–has been discussed.

We have investigated the role of adsorption water in the local transformation of multilayer graphene deposited on an oxidised silicon substrate, which was exposed to nanosecond low-intensity focused laser radiation with a wavelength of 532 nm in the air. Experimental data obtained for a laser energy density E = 0.04 J cm-2 suggest that the formation of micropits (craters) is a consequence of the multipulse removal of the layer of a water adsorbate, which is intercalated between graphene and the substrate, from the zone of laser irradiation of the graphene sheet. The energy threshold of graphene damage in the regions devoid of water was found to be higher in comparison with the initial one (0.058 against 0.048 J cm-2). According to computer simulations of the heating dynamics of the sample and the heat distribution in the substrate – adsorbate – graphene multilayer system, at energy densities corresponding to the experimental ones the water adsorbate layer heats to a temperature sufficiently high to form an increased-pressure vapour cavity under the graphene film.

To study the role of laser surface graphitization in the friction behavior of laser-patterned diamond-like carbon (DLC) films, we apply the scanning probe microscopy (SPM) in the lateral force mode (LFM) which allows to obtain simultaneously the lateral force and topography images and to determine local friction levels in laser-irradiated and original surface areas. Based on this approach in the paper, we report on (1) laser surface microstructuring of hydrogenated a-C:H and hydrogen-free ta-C films in the regime of surface graphitization using UV laser pulses of 20-ns duration and (2) correlation between the structure and friction properties of the laser-patterned DLC surface on micro/nanoscale using SPM/LFM technique. The SPM/LFM data obtained for the surface relief gratings of graphitized microstructures have evidenced lower friction forces in the laser-graphitized regions. For the hydrogenated DLC films, the reversible frictional behavior of the laser-graphitized micropatterns is found to take place during LFM imaging at different temperatures (20 and 120 °C) in ambient air. It is revealed that the lateral force distribution in the laser-graphitized areas is shifted to higher friction levels (relative to that of the unirradiated surface) at temperature 120 °C and returned back to the lower friction during the sample cooling to 20 °C, thus confirming an influence of adsorbed water layers on the nanofriction properties of laser-graphitized micropatterns on the film surface.

Experimental data on laser ablation of highly oriented pyrolitic graphite by nanosecond pulsed UV ( $$\lambda =193$$ nm) and green ( $$\lambda =532$$ nm) lasers are presented. It was found that below graphite vaporization threshold $$\approx $$ 1 J/cm $$^{2}$$ , the nanoablation regime can be realized with material removal rates as low as 10 $$^{-3}$$ nm/pulse. The difference between physical (vaporization) and physical–chemical (heating + oxidation) ablation regimes is discussed. Special attention is paid to the influence of laser fluence and pulse number on ablation kinetics. Possibility of laser-induced graphite surface nanostructuring has been demonstrated. Combination of tightly focused laser beam and sharp tip of scanning probe microscope was applied to improve material nanoablation.

We report the atomic-force-microscopy (AFM)-based nanolithography writing of surface patterns on ultrathin (4 V, and (3) the contact pressures in the GPa range results in the formation of a novel carbon phase in a nm-thick surface layer characterized by the lower density, lower mechanical strength, lower electrical conductivity, and increased nanofriction as compared to the original film. The structure of the tip-modified nm-thick layer on the ta-C film is assumed to be a structure of graphite oxide which can be further modified in the presence of water under high contact pressures.

We present the results of the study of graphene nanoablation under mechanical stress of an ultrasharp (the rounding radius is ∼2 nm) tip of a scanning probe microscope (SPM)). It was found that the SPM probe contact with graphene results in average removal of 7 · 10−3−5 · 10−2 nm of film per scan, i.e., only a few carbon atoms or clusters, in the impact area. The capability of this precision nanoablation process was shown in developing graphene nanoislands and nanoribbons ∼1 µm long and ∼10 nm wide.

A new statistical method for determining the key factors of the process of field electron emission (FEE) from nanostructures based on a comparison of the microscopic measurements of the work function of electrons with the results of a macroscopic characterization of the FEE is presented. Using the example of nanocrystalline carbon films, the possibilities of this statistical method for a quantitative estimation of the influence of the local field enhancement and the work function reduction on the FEE threshold decrease are demonstrated.

In this paper, we have studied field emission properties of highly dense arrays of multi-walled carbon nanotubes (CNTs) used as cathodes in diode-type field emission devices with a phosphor screen. For the high-density CNT emitters it is demonstrated that the emission sites are located on the CNT-cathode edges, which is direct experimental evidence of the ‘edge effect’. The results of computer simulations (using ‘ANSYS Electromagnetic’ software) are presented to confirm the experimental data and to analyze the effect of patterning on the electric field distribution for high-density CNT arrays. It is shown that selective-area removal of nanotubes in the arrays leads to the formation of additional edges characterized by the high field enhancement factor and enhanced emission from the CNT cathodes. In addition, scanning probe microscopy techniques are employed to examine surface properties of the high-density CNT arrays. For CNT arrays of ‘short’ nanotubes, the work function distribution over the sample surface is detected using a scanning Kelvin microscopy method.

The measurement data on visible and UV light reflection spectra of diamondlike a-C:H:Si films and their structural modifications caused by electrical influences in a scanning probe microscope (SPM)-lithograph are presented. Numerical evaluations of the experimental data, taking into account interference effects, show that modification is of the bulk character and causes a change in the material refractive index from n ∼ 2.2 to ∼ 1.5. A decrease in the optical density of the modified material is attributed to an increase in the film porosity in the region of SPM influences.

The results of comparative studies of laser ablation of highly oriented pyrolytic graphite in air and in an inert medium upon exposure to nanosecond pulsed laser irradiation with an energy density in the range E = 0.4 − 3 J/cm2 are presented. It is found that the nanoablation mode is established below the evaporative ablation threshold (E < Ea ≈ 1 J/cm2) in both cases (the average ablation rate is lower than 10−3 nm/pulse); in this case, the nanoablation rate in argon is lower than in air by a factor to 6. The experimental data count in favor of the oxidation mechanism of graphite nanoablation.

Scanning probe microscopy, spectroscopic ellipsometry, local reflection spectroscopy, and Raman spectrometry were used to determine the correlation between the optical and structural properties of amorphous carbon-silicon a-C:H:Si films and to study the role of the atomic structure during the formation of conical nanoobjects under an electric field in a scanning probe microscope (SPM) lithograph. Based on an analysis of the experimental data, it was shown that films in the initial state are distinguished by a high disorder of the clus- ter structure. The film material is restructured during the SPM exposure, which is accompanied by the formation of the sp 3 -bound atomic structure and nanostructuring of the sp 2 -bound carbon; in this case, the refractive index decreases by a factor of ~0.6. The latter is explained by the presence of voids in the modified material.

The present article presents the results of triboengineering tests of polycrystalline diamonds deposited chemically from the gaseous phase together with intermetallides of the Al-Ti system. The conditions are determined when the diamond wears intensively; these conditions appear due to the use of a metallic catalysis precursor as a counterbody. The study results are expected to contributed to the development of techniques for machining of diamonds of industrial dimensions.

In this paper we report on investigations of field emission (FE) properties of semiconducting (SiC, ZnO) one-dimensional (1D) nanostructures – nanowire/nanorod arrays, and fabrication of low-voltage field emission display (FED) devices based on these 1D nanomaterials. SiC nanowires were grown on Ni-coated Si substrates using a thermal metal-organic chemical vapor deposition (MOCVD) technique, and ZnO nanostructures were grown on gold-coated Si substrates by a thermal CVD method. Electron field emission properties of SiC and ZnO nanostructures were examined in plane geometry using a flat phosphor screen. The interrelation between the FE characteristics (emission thresholds, current density, surface uniformity, etc.) and microstructure and surface morphology of the produced 1D nanostructures was established. Diode-type FED devices (flat vacuum lamps) with SiC-nanowire-based cathodes were developed and fabricated. The FEDs are characterized by low threshold and operating electric fields – lower 2 V/μm and 5 V/μm, respectively, high current density and brightness, and stable performance of the nanowire-based cathodes.

The results of a study of a new type of regular carbon nanostructures, namely, nanocones on the film surfaces of carbon-silicon composites of the (a-C:H):Si type are given in this paper. Nanocones appear under the action of the electric field of the probe of an air-operated scanning probe microscope (SPM) in the case where the values of the voltage amplitude and the exposure times exceed the threshold ones. The produced nanoobjects preserve their shapes at thermal annealing up to 700°C. It is assumed that the process of nanocone formation is related to the local transformation of the carbon-silicon composite structure from the amorphous to the nanocrystalline state in the electric field of the SPM probe.

Some aspects of Scanning Probe Microscopy (SPM) — based nanostructuring of (a-C:H):Si composite films, including (i) correlations between geometrical and electrical properties of modified regions during SPM actions, (ii) deviations of the nanocone shape under heat treatment, and (iii) the influence of ambient humidity on the nanocone growth, were studied. The investigations revealed an initial period of SPM actions, during which no modification of the film surface was registered. On finishing this period, the film conductivity was found to rapidly decrease, and just at this moment the nanocone growth started. The formed nanocone kept its shape after heat treatments up to 700 °C under vacuum conditions of ∼ 100 Pa. It was also found that the higher the humidity, the faster was the nanocone growth. The latter was accompanied by the formation of a corrugated pedestal. The nature of the observed phenomenon is discussed.

Structural properties of carbon–silicon composite films, grown by PE CVD technique on Si substrates, were examined using Auger electron spectroscopy (AES), X-ray diffraction (XRD) and scanning probe microscopy (SPM) before and after SPM tip-induced actions. Metal-free (a-C:H):Si films were found to be considered as a polymer-like material with either amorphous or nanocrystalline structure, consisting of hydrocarbon chains with different molecular masses and lengths. For Mo-doped films, a higher content of structurally ordered atomic groups was registered as compared to the metal-free films. A new effect of nanostructuring, i.e. the formation of nanocones under the action of local electric field in the metal-free films, was observed. Evidence was obtained in favor of local recrystallization of the nanoscale regions of the amorphous material under the SPM actions.

Low-conducting hydrogenated diamond-like carbon (a-C:H) films were examined for the purpose of nanometer-scaled modifications under the action of local electrical field. To create the modifications, a series of voltage pulses (either positive or negative, or bipolar) was applied between the sample and the cantilever at regular points along a given line while scanning the probe in contact mode under ambient conditions. It was established that both geometrical and electrical properties of the obtained nano-objects strongly depended on the pulse shape. A nanocavity with a well-conducting bottom was reproducibly formed under the bipolar voltage pulses. Otherwise, the actions mostly resulted in the formation of poorly conducting nanoprotrusions. Evidence was obtained that, in the case of monopolar voltage pulse actions, local heating of the surface layer underneath the probe is a dominant process in the mechanism of the nanoprotrusion formation. We consider that the bipolar pulse actions additionally involve the tip-surface electrostatic interaction which plays an important role in the formation of nanocavities.

This work reports on electronic properties of nitrogen-doped, n-type ultrananocrystalline diamond (UNCD) films grown on p-type Si substrates from CH 4 -Ar-N 2 gas mixtures using a microwave plasma chemical vapor deposition technique. Films ∼1 μm thick were grown with 5%N 2 and 10%N 2 in the plasmas. Charge-based deep-level transient spectroscopy showed a shallow level of point defects with an activation energy of ∼0.05 eV. The density of these shallow defects was increased with increasing nitrogen content in the plasma. Complex scanning probe microscopy methods were applied to study the film microstructure. Generally it was found that the nitrogen-doped UNCD films showed a periodic 'cell-like' structure in which the cell with a lateral size of several nanometers was less conducting than the boundary between the cells. The boundary width was found to be 0.5-1 nm. The observed details of the periodic structure can be associated with diamond nanocrystallites (grains) and grain boundaries, respectively. In addition, 2-5 nm high-conducting inclusions clustered on the film surface were observed. It was noted that the emission field was inversely proportional to the film electroconductivity, and the lowest emission field of F ∼ 10 V μm -1 was detected near the high-conducting inclusions. Moreover, the surface electron potential at the emission sites was lowered. The reasons why the shallow donor center is predominantly introduced by nitrogen incorporated into the grain boundaries and the possible mechanisms of low-field electron emission from the nitrogen-doped UNCD films have been discussed.

Low-threshold field electron emission (FEE) is reported for periodic arrays of micro-tips produced by laser ablation of Si wafers. The best samples show emission at threshold fields as low as 4–5 V/μm for n-type Si substrates and of 1–2 V/μm for p-doped Si substrates, as measured with a flat-screen technique. Auger electron spectroscopy and X-ray electron spectroscopy reveal island-like deviation of the SiO2 stoichiometry on the tip surfaces, with lateral dimensions of less than 100 nm. Microscopic studies using a special field-emission STM show that the emission originates from well-conducting regions of sub-micron size. The experimental data suggest FEE from the tip arrays by a geometric field enhancement of both the individual micro-tip and the narrow conducting channels in the tip body.

Local ablation of graphitic layers by SPM probe was investigated. The gap between the tip and sample surface was varied. Mono and bipolar electric impulses were applied. Influence of various processing parameters on graphite ablation rates was investigated. Shallow craters and structures with halfwidth as low as 15 nm were produced. Electromechanical mechanism of graphite nanoablation is discussed.

Results on a complex study of macroscopic and microscopic electronic properties of nanocrystalline diamond and related material (BN, GaN, CN) films are presented. It was found that all the samples studied showed similar dependencies of macroscopic emission parameters (the Fowler–Nordheim work function, the effective emitting area) on the film emissivity. Also, some microscopic properties were found to be common for all the films tested. It was generally observed that field electron emission occurred at nanosized regions on the boundary of high and low resistivity areas, and peaks of the emission intensity were associated with a lowered surface electron potential. Based on the experimental data, a mechanism of field electron emission from the surface of nanocrystalline films is proposed. We suppose that electrons are transported from narrow conducting channels into vacuum through specific low-dimensional regions, the electronic properties of which, due to the quantum size effect, are different from the bulk material. In this case the base material grains play a role of the conductive channel-containing matrix as well as a heat sink. Details of the new low-field emission mechanism including the filling of discrete energy states, and the decrease in the work function under the action of electric field are discussed.

Properties of the field electron emission for different diamond/sp2-bonded carbon nanostructures including chemical vapor deposition (CVD) diamond films and diamond/pyrocarbon composites are considered with respect to their structure. It is noted that the samples showing the emission at low threshold fields of 1–3 V/μm with satisfactory spatial uniformity typically contain a lot of sp2-bonded carbon phase, while samples which have a predominant diamond phase emit poorly. Studying the microscopic properties of the emission centers with special STM device it was found, that the emission is associated just with diamond/sp2-bonded carbon interfaces and thin conducting layers. Possible mechanisms of the emission including local field enhancement and reducing of the tunneling barrier due to NEA are analyzed. It is proposed to describe the emission from the samples using quantum well effects at thin carbon nanolayers and insulator/graphite interfaces. The mechanism does not suggest taking into account specific diamond properties, and it could be suitable for wide range of objects.

X-ray induced modification of the electronic properties of nanocrystalline boron nitride (BN) films with different compositions and carbon impurity contents is reported. The related changes of the surface composition and valence band structures of the irradiated films are discussed. X-ray irradiation of nanocrystalline BN films is shown to widen areas with intermediate values of electroconductivity (associated with areas of high emission density) and to increase the average value of electroconductivity by redistributing surface potentials and electron emission sites. Improvement of the field emission is observed with both increasing electron current and diminishing thresholds. Longer x-ray irradiation times yield greater improvement.

Using the functional capabilities of a special scanning tunneling field emission microscope (STFEM), a new measuring procedure for studying the electronic properties of the emission sites of low-field emitting materials has been developed. The position of intensive, separately situated emission sites (‘individual’ emission centres) was determined over a large surface area, whereupon both an electron escape and a surface electron potential at the ‘individual’ centre were investigated in detail. We report on the experimental results of the STFEM study of electronic properties of low-field emitting diamond films which have a composite structure consisting of diamond and nanocrystalline graphite phases, and show stable electron emission at fields 3–8 V/μm. We observed a non-monotonous dependence of the electron escape from the emission site on the bias voltage — i.e. in a certain voltage range, the electron escape decreased with increasing voltage. Also, in the same voltage range, the effective surface potential barrier at the emission site shows a peak value. It is supposed that such anomalous electronic properties are due to resonant tunneling through the grain boundary region near the interface of the diamond and graphite phases. In addition, the results of energy resolved electron emission measurements are analyzed. The emission spectra show a cut-off at high energies and a tail towards low energies. The best approximation of the spectrum tail is reached if electron tunneling through a triangular potential barrier of 0.1–0.2 eV relative to the Fermi level of the diamond film substrate, and the emission field of 50–100 V/μm are taken into account. It thus can be supposed that the electrons are emitted from the valence band, and the electric field at the emission site is enhanced. A possible mechanism for the low-field electron emission from chemical vapor deposited (CVD) diamond films, including both the geometric field enhancement and the quantum well effect at the grain boundary, is discussed.

We propose closed analytic expressions reducing the stresses typical of a physically inadmissible state obtained as a result of the numerical solution of a quasistatic elastoplastic problem to the state corresponding to the yield surface. The Lagrange functional is modified to remove the excess stresses at the points where the condition of yield is violated, which enables one to maintain the equilibrium state of the elastoplastic body in each stage of loading.

A special scanning tunneling-field emission microscope (STFEM) has been used for studying field electron emission from thin nanocrystalline diamond films grown by a DC plasma CVD. These are characterized by turn-on electric fields as low as 3.5 V/μm and by long-term stability of the emission current. Comparing different surface properties (topography, field electron emission intensity, surface potential and local electroconductivity distributions) on a large surface area it was found that, in most cases, emission centre position is not coincident with peaks of the surface profile. It has been noted that the diamond films studied are composed from nano-grained phases distinguished by their physical properties. These are thought to be diamond and graphitic phases. The low-field electron emission from the samples studied is considered to be associated with the presence of these phases. The results of the STFEM mapping have been compared with data on macroscopic current/field field emission characterization. The mechanisms governing low-field electron emission from nanoscale diamond films are discussed.

Diamond–carbon nanocomposites (DCN) containing diamond and graphitic particles, both a few nanometers in size, were studied as the material for field electron emission. Diamond–carbon mass ratio and grain size were varied to optimize field emission properties. The stable and uniform electron emission was observed at fields E=10 V μm−1 with a negligible hysteresis of I–V curves. Treatment in microwave hydrogen plasma was found to reduce the threshold field for emission owing to preferential etching of carbon component and surface relief sharpening. Ultrathin chemical vapour deposition diamond films can be easily grown on DCN due to the very high nucleation density inherent to this composite.

We have investigated the electron field emission characteristics of BN and CN on highly conductive silicon thin films deposited by End-Hall ion source and electron cyclotron resonance plasma source-assisted physical vapor deposition. The thermal processing and surface laser modification effects on the field emission properties were investigated. Current density-field emission characteristics Iη(E) were tested in a high vacuum environment. Mg-doped BN thin films on silicon exhibited a turn-on field as low as 25 V/μm and a current density higher than 1 A/cm2. The deposition of a thin BN layer on copper lithium (CuLi) metallic substrate yields surfaces with a 75 V/μm onset field and a current density 1000 times higher than that obtained from uncoated surfaces. Under high vacuum laser annealing BN coated CuLi showed no enhancement but more stable emission characteristics. Our results show also that pulsed ultraviolet laser irradiation of CN films in vacuum results in an increase of the field emission current ...

Results are reported on microscopic study of electronic and structural properties of field emission centers for chemical vapor deposition diamond films. The field electron emission (FEE) for the best films studied was observed at >3 V μm−1, and ultralow (

For ultrathin carbon films with controllable graphite nanophase contents, direct experimental evidence is found that the work function of electrons decreases with reduction of characteristic dimensions (thickness). The observed effect is associated with the splitting of the electron states in ultrathin films, as in the 2D quantum well.

The principles of scanning tunnelling microscopy (STM) are extended to the study of field electron emission from metal, semiconducting and semi-insulating materials. A specially designed, high-vacuum STM device called a scanning tunnelling field emission microscope (STFEM) is constructed, and new measuring procedures are developed to examine complex physical properties of emission centres. Providing high bias voltages and fast mapping of large squares, the STFEM allows one to obtain reliable statistical data on surface properties, namely topography, emission intensity, surface potential distribution and local electroconductivity. Results from a study of low-field electron emission from CVD diamond films are described to illustrate the functional capabilities of the new STM device. It was found that the diamond films studied are composed of nanograined phases distinguished by their physical properties. It has also been noted that the low-field electron emission from the studied samples is associated with the interfaces of these phases.

The effects of the surface modification of diamond films with thin Ni layers and of the influence of the Ni/diamond structures, on photoelectron emission induced by KrCl excimer laser (222 nm wavelength) pulses of a nanosecond duration, were studied. The Ni/diamond structures were prepared by deposition of ultrathin nickel coatings (≈2 nm thick) onto 1 μm thick diamond films on Si. The photocurrent induced by the UV laser pulses from a Ni-coated diamond surface was found to increase as compared with the photocurrent from the original film surface. Using Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) techniques, the electronic structure of the Ni-coated and as-grown surfaces, and the chemical state of nickel and surface band bending, were investigated. It is discussed that the formation of the downwards band bending and a lowering of the surface work function are responsible for the observed enhancement of laser-induced electron emission from the Ni-coated diamond films.

Two-dimensional calculations by the TIGR code [Izv. Sib. Otd. Akad. Nauk SSSR 8, 74 (1967); Vop. Atom. Nauk Tekh. Met. Prog. Chisl. Resh. Zad. Mat Fiz. 3, 34, (1984)] have verified the main result of the theoretical research on the limitation of perturbation growth at the ablation front, which appeared in the planar foils irradiated by laser flow in the regime of accelerated motion of the ablation front. It is shown by calculations that the growth rate γ, characterizing the perturbation growth, achieves its maximal value γm at some wave number km, which is defined by initial parameters of the problem—acceleration at the ablation front g and velocity of ablation ua. It is in good agreement qualitatively and quantitatively, with theoretical results obtained earlier by some authors. It is shown by calculations that for k>km, as it proceeds from the theory, the growth rate decreases down to zero. Simulations of turbulent mixing on the basis of the Ke model is implemented. For the thin foil case considered, an analytic estimate of the effect of turbulent mix, which included Takabe’s formula, showed ablation reduced in the coefficient in the mixing equation by a factor of 25. Theoretical and numerical research on the influence of turbulent mixing on the performance of the compressed part of the plate has been conducted.

Diamond-like carbon (DLC) films 4–400 nm thick were deposited on conductive n -Si and metal substrates using direct ion beam deposition from an RF inductively coupled CH 4 -plasma (ICP) source. The field electron emission of the films was examined as a function of deposition conditions and post-deposition surface modification by Ni ultrathin coatings. Electrical properties of the films were studied as well. A specially designed high vacuum scanning tunnelling-field emission microscope was employed for simultaneous mapping of the topography, work function and local field electron emission intensity. Stable, low voltage emission was observed after the emission electric field/current activation process. The activation mechanism was probably the formation of conductive channels in the films to supply electrons for emission from low work function surface areas. Deposition of ultrathin metal coatings on the DLC films reduced both the effective barrier height and the field emission threshold. The DLC films surface coated with ultrathin Ni films resulted in electron emission at fields as low as 20–25 V μm −1 . It was shown that DLC films with thicknesses in the range 5–15 nm demonstrated efficient field emission long-term stability. The results are interpreted based on the reduced electrical resistivity of nanometer scale thick films, and deviation of resistivity over the surface.

The results of ID-ERA and 2D-TIGR, OMEGA codes calculations of compression and burn of indirect-driven targets for the thermonuclear ignition and Engineering Test Facility are presented. The possibility to obtain high-energy yield of G > 100 with driver energy of Ed = 5−10 MJ by using the heavy-ion one-beam accelerator as the main driver and powerful laser for fast ignition of thermonuclear detonation of cylindrical targets is pointed out.

Single nanoemitters of electrons – hill-shaped carbon nano-objects – were fabricated with various sizes and configurations on thin diamond-like films by means of a local chemical vapor deposition (CVD) technique in a scanning tunneling microscope (STM) lithograph. A definite correlation between the nano-object height and surface electron potential has been established with the STM. It was found that, below a critical object thickness of about 15 nm, the surface electron potential was substantially lowered for smaller nano-objects (twice the decrease in the information signal for the 3-nm-thick features). The data obtained is considered to be strong evidence of low-dimensional effects in the process of low-threshold field electron emission observed earlier for nanostructured carbon materials.

This article discusses mechanisms of scanning-tunneling-microscopy-based nanolithography of ultrathin diamond-like α-C:H films. Results of films modification by short voltage pulses in scanning tunneling microscope (STM) was verified in constant current STM and conductive atomic force microscope (AFM). Critical parameters for STM-nanolithography by this method were determined. Results of modification in ambient conditions and in low vacuum are compared.

In this paper, experimental data are presented on the synthesis and properties of nanocrystalline diamond (NCD) films grown by a dc plasma CVD technique from various gas mixtures (CH4-H2, CH4-H2-Ar, CH4-Ar, CH4-H2-N2, CH4-Ar- N2). The interrelation between the CVD conditions, the film microstructure and film properties is established using Raman spectroscopy, XRD, XPS, AES, SEM, TEM, AFM/STM, spectroscopic ellipsometry and optical transmission spectroscopy techniques. Experimental methods for laser assisted fabrication of ultrathin and highly smooth NCD films are described. Effects of the deposition parameters (substrate temperature, CH4 content, addition of Ar gas to CH/H2 gas mixtures) on the grain size, surface roughness and optical properties of NCD films are discussed. Results of nitrogen doping of nanocrystalline diamond films are presented and discussed.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Presented in this paper is a new effect of nanostructuring, namely the formation of nano-cones under the action of local electric field induced in carbon-silicon composite films underneath the SPM probe

Low-conducting hydrogenated diamond-like carbon (DLC) a-C:H films were examined for the purpose of nanometer-scaled modifications under the action of local electrical field. The capabilities of SPM technique for preparation of conducting nanostructures in the low-conducting a-C:H films have been demonstrated for the first time.

Diamond deposition on patterned substrate surfaces is considered, primarily as the step to produce CVD diamond components by molding technique. The importance of substrate seeding process to obtain high diamond nucleation density and conformal coatings is underlined. In case of free-standing films the morphology, defects and impurities of fine-grained nucleation (substrate) side are different from those on growth side. Examples of the molding technique for manufacturing of various diamond shapes, from micron-scale pyramidal arrays for optics and field electron emitters to centimeter size X-ray refractive lenses, are presented.

Results are presented on a complex study of field electron emission (FEE) and structural correlations for nanocrystalline diamond and nitride films. It was found that all the samples studied showed similar dependences of the Fowler–Nordheim work function and effective emitting area on the threshold emission field. Besides it was generally observed that FEE occurred at nanosized regions on the boundary of high and low conducting areas, and peaks of the emission intensity were associated with a lowered surface electron potential. Based on the experimental data, the following mechanism of low-FEE from the materials studied can be supposed. Electrons are transferred from the conducting channel into a vacuum through the low-dimensional region where the emission probability is high due to the quantum well effect. A physical model of the electron escape from a quantum well was analyzed. As follows from the estimations, the quantum size effect, being combined with a moderate field enhancement (the field enhancement factor β =10–100), allows us to explain the observed variation in the energetic parameters for the samples studied. The function of the insulating grains is mainly to support the conducting channels in the sample body. Also, the grains can fulfill an additional function of the heat sink.