Thin SiCx films were fabricated by hybrid laser–magnetron deposition system. KrF excimer laser was used for deposition of carbon and
magnetron at the same time for sputtering of Si species. Films were fabricated in argon/hydrogen ambient with and without
additional RF discharge. The substrate temperature was changed up to 700°C. Films topology, crystallinity, composition, chemical
bonds and optical emission spectra were studied. Films were smooth and amorphous. Films of thickness 400–1000 nm were fabricated.
Adhesion moved from 8 to 14 N, depending on deposition conditions. 相似文献
The structure of thin films deposited by pulsed laser ablation (PLD) is strongly dependent on experimental conditions, like
laser wavelength and fluence, substrate temperature and pressure. Depending on these parameters we obtained various kinds
of carbon materials varying from dense, mainly tetrahedral amorphous carbon (ta-C), to less compact vertically oriented graphene
nano-particles.
Thin carbon films were grown by PLD on n-Si 〈100〉 substrates, at temperatures ranging from RT to 800°C, from a rotating graphite target operating in vacuum. The laser ablation of the graphite target was performed by a UV pulsed ArF excimer laser (λ=193 nm) and a pulsed Nd:YAG laser, operating in the near IR (λ=1064 nm).
The film structure and texturing, characterised by X-ray diffraction analysis, performed at grazing incidence (GI-XRD), and
the film density, evaluated by X-ray reflectivity measurements, are strongly affected both by laser wavelength and fluence
and by substrate temperature.
Micro-Raman and GI-XRD analysis established the progressive formation of aromatic clusters and cluster condensation into vertically
oriented nano-sized graphene structures as a direct function of increasing laser wavelength and deposition temperature. The
film density, negatively affected by substrate temperature and laser wavelength and fluence, in turn, results in a porous
bulk configuration and a high macroscopic surface roughness as shown by SEM characterisation. These structural property modifications
induce a relevant variation also on the emission properties of carbon nano-structures, as evidenced by field emission measurements.
This work is dedicated to our friend Giorgio who passed away 20th August. 相似文献
This letter describes the synthesis and structural characterization of monolithic carbon aerogel (CA) materials that possess both high surface areas and hierarchical porosity. Thermal activation of a macroporous CA structure, one that was derived from an acetic acid-catalyzed sol-gel polymerization reaction, yields monolithic materials with large pore volumes and surface areas exceeding 3000 m2/g. Given the flexibility of CA synthesis, this approach offers viability to engineer new materials for use as catalyst supports, electrodes, capacitors and sorbent systems. 相似文献
a-C:H films were prepared by closed-field unbalanced magnetron (CFUBM) sputtering on silicon substrates using argon (Ar) and acetylene (C2H2) gases, and the effects of post-annealing temperature on structural and mechanical properties were investigated. Films were annealed at temperatures ranging from 300 °C to 700 °C in increments of 200 °C using rapid thermal annealing equipment in vacuum ambient. Variations in microstructure were examined using Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Surface and mechanical properties were investigated by atomic force microscopy (AFM), nano-indentation, residual stress tester, and nano-scratch tester. We found that the mechanical properties of a-C:H films deteriorated with increased annealing temperature. 相似文献
Diamond-like carbon (DLC) films were deposited on Si(1 0 0) substrates using plasma deposition technique. The deposited films were irradiated using 2 MeV N+ ions at fluences of 1×1014, 1×1015 and 5×1015 ions/cm2. Samples have been characterized by using Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM). Analysis of Raman spectra shows a gradual shift of both D and G band peaks towards higher frequencies along with an increase of the intensity ratio, I(D)/I(G), with increasing ion fluence in irradiation. These results are consistent with an increase of sp2 bonding. XPS results also show a monotonic increase of sp2/sp3 hybridization ratio with increasing ion fluence. Plan view TEM images show the formation of clusters in the irradiated DLC films. HRTEM micrographs from the samples irradiated at a fluence of 5×1015 ions/cm2 show the lattice image with an average interplanar spacing of 0.34 nm, revealing that the clusters are graphite clusters. The crystallographic planes in these clusters are somewhat distorted compared to the perfect graphite structure. 相似文献
Monodisperse nanoporous carbon spheres (NCS) were synthesized in large quantities via a facile hydrothermal synthesis. It is found that the NCS have rough surfaces with a large quantity of uniformly distributed protruding and concaving zones. Large quantities of nanopores of about 0.3 nm in diameter are distributed uniformly on the whole sphere surfaces. The effects of reaction parameters on the surface roughness, sphere diameter and pore size of NCS were investigated. Taking the NCS as substrates, silver nanoparticles (NPs) were deposited onto their surfaces using a one-step ultrasonic electrodeposition procedure. The deposited silver NP has a uniform distribution, a high particle density and a narrow size range of 12-16 nm in diameter. This study demonstrates an efficient approach to fabricate noble-metal/carbon nanocomposites. 相似文献
Laser beam micromachining was applied to super-hard nano-polycrystalline diamond (NPD) synthesized by the direct conversion
of graphite at high pressure and high temperature. Three types of pulsed lasers were tested: nanosecond near-infrared, nanosecond
near-ultraviolet, and femtosecond near-infrared lasers. The latter two were also applied for synthetic single crystal of diamond
to compare the results with those of the NPD. It was demonstrated that the nanosecond near-infrared laser was the most efficient
device for rough shaping of the NPD, while the ultraviolet and femtosecond lasers give satisfactory results for precise surface
finishing of it. The properties of the laser-processed surfaces were analyzed by scanning and transmission electron microscopy,
laser scanning microscopy, and micro Raman spectroscopy. These analyses demonstrated that the three types of lasers play different
and complementary roles, and that their combination is the best suitable solution for micromachining of the hardest diamond
into any desired shapes. 相似文献
Amorphous carbon–sulfur (a-C:S) composite films were prepared by vapor phase pyrolysis technique. The structural changes in
the a-C:S films were investigated by electron microscopy. A powder X-ray diffraction (XRD) study depicts the two-phase nature
of a sulfur-incorporated a-C system. The optical bandgap energy shows a decreasing trend with an increase in the sulfur content
and preparation temperature. This infers a sulfur incorporation and pyrolysis temperature induced reduction in structural
disorder or increase in sp2 or π-sites. The presence of sulfur (S 2p) in the a-C:S sample is analyzed by the X-ray photoelectron spectroscopy (XPS). The sp3/sp2 hybridization ratio is determined by using the XPS C 1s peak fitting, and the results confirm an increase in sp2 hybrids with sulfur addition to a-C. The electrical resistivity variation in the films depends on both the sulfur concentration
and the pyrolysis temperature. 相似文献
We report on electrical measurements and structural characterization performed on boron-doped diamond-like carbon thin films
deposited by femtosecond pulsed laser deposition. The resistance has been measured between 77 and 300 K using four probe technique
on platinum contacts for different boron doping. Different behaviours of the resistance versus temperature have been evidenced
between pure DLC and boron-doped DLC. The a-C:B thin film resistances exhibit Mott variable range hopping signature with temperature.
Potential applications of DLC thin films to highly sensitive resistive thermometry is going to be discussed. 相似文献
Graphene, the two‐dimensional form of carbon presents outstanding electronic and transport properties. This gives hope for the development of applications in nanoelectronics. However, for industrial purpose, graphene has to be supported by a substrate. We focus here on the graphene‐on‐SiC system to discuss how the SiC substrate interacts with the graphene layer and to show the effect of the interface on graphene atomic and electronic structures.