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The MOCVD growth of Ga and In microparticles was performed on graphene/SiC substrates. The test of effectiveness of the microparticles grown for SERS was based on the observation of H–Si vibrations on hydrogenated graphene grown on SiC. It was shown by scanning electron microscopy that the Ga or In microparticles grown were in the form of hemispheres with a flat side attached to the substrate. Raman measurements have shown that the effective H–Si SERS signal arises at the edges of the hemisphere microparticles. In addition, it was found that Ga or In microparticles are covered by GaAs or InAs shells, respectively. The presence of GaAs and InAs coverage of metallic microparticles arises from the As contamination of the MOCVD system used for III–V compound growth. However, these coverages do not significantly affect the surface plasmons resonance in the metallic microparticles.

The main aim of the work was investigation of the graphene resistance on mechanical scratch after ion beam bombardment. The CVD graphene on the glass substrate was used. Bombardment of graphene by beams of helium and nitrogen ions of energy 100 keV was applied. Density of ion induced defects in graphene was evaluated using Raman spectroscopy. The polymer indenter was applied for scratch test. Increase of the scratch resistance of the graphene after ion beam bombardment was observed. Scratch resistance of the graphene layer increases with increasing density of defects induced by helium and nitrogen ions. The shape of graphene ribbons exfoliated during scratch test suggests that increase of graphene scratch resistance is accompanied with improvement of graphene adhesion to the substrate. It suggests that ion beam induced defects may be responsible for observed increasing of both graphene scratch resistance ad graphene adhesion to the substrate.

Water vapor penetrates through defects in graphene layers grown on Ge(001)/Si(001) substrates and oxidization of germanium forming GeO2 is described. The presence of trigonal GeO2 underneath of graphene has been identified by Raman measurements. It has been found that formation of blisters of GeO2 under graphene leads to dramatic increase of intensity of graphene Raman spectrum. The increase is the most likely due to screening of graphene by GeO2 from nano-faced Ge(001) surface.

The CVD graphene deposited on the glass substrate was bombarded by molecular carbon ions C 3 + C 6 + hydrocarbon ions C 3 H 4 + and atomic ions He + , C + , N + , Ar + , Kr + Yb + . Size and density of ion induced defects were estimated from evolution of relative intensities of Raman lines D (∼1350 1/cm), G (∼1600 1/cm), and D′ (∼1620 1/cm) with ion fluence. The efficiency of defect generation by atomic ions depend on ion mass and energy similarly as vacancy generation directly by ion predicted by SRIM simulations. However, efficiency of defect generation in graphene by molecular carbon ions is essentially higher than summarized efficiency of similar group of separate atomic carbon ions of the same energy that each carbon ion in a cluster. The evolution of the D/D′ ratio of Raman lines intensities with ion fluence was observed. This effect may indicate evolution of defect nature from sp3-like at low fluence to a vacancy-like at high fluence. Observed ion graphene interactions suggest that the molecular ion interacts with graphene as single integrated object and should not be considered as a group of atomic ions with partial energy.

Ion induced defect generation in graphene was analyzed using Raman spectroscopy. A single layer graphene membrane produced by chemical vapor deposition (CVD) on copper foil and then transferred on glass substrate was subjected to helium, carbon, nitrogen, argon and krypton ions bombardment at energies from the range 25 keV to 100 keV. A density of ion induced defects and theirs mean size were estimated by using Raman measurements. Increasing number of defects generated by ion with increase of ion mass and decrease of ion energy was observed. Dependence of ion defect efficiency (defects/ion) on ion mass end energy was proportional to nuclear stopping power simulated by SRIM. No correlation between ion defect efficiency and electronic stopping power was observed.

Single layer graphene grown by chemical vapor deposition (CVD) method on Cu foil and then transferred onto a borosilicate glass substrate was used in the experiments. The graphene samples were irradiated by singly charged ions of helium, nitrogen, argon or krypton at the energy of 100 keV up to fluence ranging from 1 × 1011 cm− 2 to 1 × 1016 cm− 2. Raman spectroscopy was used for the detection of defect size and density in graphene caused by ion irradiation. The ion induced defect size and density were determined from the Raman spectra measurements. The applicability of the SRIM code for simulation of defects generation by ions in graphene was tested. Finally, the controlled generation of the defects in graphene by using ion implantation was verified.

A method of growing highly oriented MoS2 is presented. First, a Mo film is deposited on a graphene/SiC(0001) substrate and the subsequent annealing of it at 750 °C leads to intercalation of Mo underneath the graphene layer, which is confirmed by secondary ion mass spectrometry (SIMS) measurements. Formation of highly oriented MoS2 layers is then achieved by sulfurization of the graphene/Mo/SiC system using H2S gas. X-ray diffraction reveals that the MoS2 layers are highly oriented and parallel to the underlying SiC substrate surface. Further SIMS experiments reveal that the intercalation process occurs via the atomic step edges of SiC and Mo and S atoms gradually diffuse along SiC atomic terraces leading to the creation of the MoS2 layer. This observation can be explained by a mechanism of highly oriented growth of MoS2: nucleation of the crystalline MoS2 phase occurs underneath the graphene planes covering the flat parts of SiC steps and Mo and S atoms create crystallization fronts moving along terraces.

We demonstrate the demodulation of a multi-Gb/s ON–OFF keying (OOK) signal on a 96 GHz carrier by utilizing a 250-nm graphene field-effect transistor as a zero bias power detector. From the eye diagram, we can conclude that the devices can demodulate the OOK signals up to 4 Gb/s.

The paper presents an interaction of Ti/Ti-oxides with: Si(100), HOPG(0001) and graphene/4H-SiC(0001) substrates. A thin layer (~3 nm) of Ti was deposited by means of DC sputtering technique on all the considered substrates. XPS, AFM and Raman spectroscopy were applied to find out the differences in interaction of Ti/Ti-oxides with selected substrates under UHV annealing. In the case of Si(100), substrate, apart from the expected TiO2, the presence of TiSi2 and TiSiOx components and the easiest reduction towards Ti2O3 was observed under UHV annealing. The sample exhibited also substantial evolution of surface morphology without the change of surface roughness which was attributed to formation of TiSi2 and TiSiOx components. This was in contrast with HOPG substrate where an annealing-induced agglomeration of the deposited material increased the surface roughness substantially. However, in the case of Ti/Ti-oxides deposited on graphene/4H-SiC(0001), UHV annealing caused no noticeable change of surface morphology. Agglomerates were not formed which was attributed to degradation of graphene (confirmed by Raman spectra) and supressing van der Waals' interactions responsible for easy surface diffusion. The differences in morphology were also discussed in the context of the surface energy of selected substrates.

Boron nitride films were grown on 2-inch sapphire substrates using the MOCVD technique. The growth was performed using a pulsed source injection mode with triethylborane (TEB) and ammonia (NH3) with a high V/III ratio, which corresponds to the self-terminated growth mode. Two different carrier gases, H2 and Ar, were used to investigate their influence on the growth mechanism, while all the other growth parameters were kept the same. The BN films thus obtained were examined using XRR, SIMS, Raman spectroscopy, ATR spectroscopy, SEM and AFM. A difference was found in the surface roughness. The BN films grown in an H2 atmosphere had a surface roughness three times smoother than those grown in Ar. However, the main difference was brought to light by SIMS measurements. The SIMS measurements revealed that growth under an H2 flow leads to a reduction in carbon concentration by more than four orders of magnitude. It was also shown that the boron distribution in the BN film grown under an H2 flow is very uniform. It is discussed that this mechanism is related to the reactions between TEB and NH3 in the presence of H2. The elimination of carbon by using hydrogen reveals its role in BN growth, which is indeed essential.

Ion bombardment of graphene leads to the formation of defects which may be used to tune properties of the graphene based devices. In this work, however, we present that the presence of the graphene layer on a surface of a sample has a significant impact on the ion bombardment process: broken sp2 bonds react with the incoming ions and trap them close to the surface of the sample, preventing a standard ion implantation. For an ion bombardment with a low impact energy and significant dose (in the range of 1014 atoms cm-2) an amorphization of the graphene layer is observed but at the same time, most of the incoming ions do not penetrate the sample but stop at the surface, thus forming a highly doped ultra-thin amorphous carbon layer. The effect may be used to create thin layers containing desired atoms if no other technique is available. This approach is particularly useful for secondary ion mass spectrometry where a high concentration of Cs at the surface of a sample significantly enhances the negative ionization probability, allowing it to reach better detection limits.

Various experimental data revealing large-area high-quality graphene films grown by the CVD method on Ge(001)/Si(001) substrates are presented. SEM images have shown that the structure of nano-facets is formed on the entire surface of Ge(001), which is covered by a graphene layer over the whole macroscopic sample surface of 1 cm(2). The hill-and-valley structures are positioned 90° to each other and run along the100direction. The hill height in relation to the valley measured by STM is about 10 nm. Raman measurements have shown that a uniform graphene monolayer covers the nano-facet structures on the Ge(001) surface. Raman spectroscopy has also proved that the grown graphene monolayer is characterized by small strain variations and minimal charge fluctuations. Atomically resolved STM images on the hills of the nanostructures on the Ge(001) surface have confirmed the presence of a graphene monolayer. In addition, the STS/CITS maps show that high-quality graphene has been obtained on such terraces. The subsequent coalescence of graphene domains has led to a relatively well-oriented large-area layer. This is confirmed by LEED measurements, which have indicated that two orientations are preferable in the grown large-area graphene monolayer. The presence of large-area coverage by graphene has been also confirmed by low temperature Hall measurements of a macroscopic sample, showing an n-type concentration of 9.3 × 10(12) cm(-2) and a mobility of 2500 cm(2) V(-1) s(-1). These important characteristic features of graphene indicate a high homogeneity of the layer grown on the large area Ge(001)/Si(001) substrates.

A Chemical Vapor Deposition graphene monolayer grown on 6H&ndash, SiC (0001) substrates was used for implantation experiments. The graphene samples were irradiated by He+ and N+ ions. The Raman spectra and electrical transport parameters were measured as a function of increasing implantation fluence. The defect concentration was determined from intensity ratio of the Raman D and G peaks, while the carrier&rsquo, s concentration was determined from the relations between G and 2D Raman modes energies. It was found that the number of defects generated by one ion is 0.0025 and 0.045 and the mean defect radius about 1.5 and 1.34 nm for He+ and N+, respectively. Hole concentration and mobility were determined from van der Pauw measurements. It was found that mobility decreases nearly by three orders of magnitude with increase of defect concentration. The inverse of mobility versus defect concentration is a linear function, which indicates that the main scattering mechanism is related to defects generated by ion implantation. The slope of inverse mobility versus defect concentration provides the value of defect radius responsible for scattering carriers at about 0.75 nm. This estimated defect radius indicates that the scattering centres most likely consist of reconstructed divacancies or larger vacancy complexes.