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This paper introduce the formation of alumina matrix composites reinforced with multilayered graphene, graphene oxide and nickel-phosphorus coated multilayered graphene. The powder metallurgy technique followed by the Spark Plasma Sintering (SPS) method were utilized to fabricate the specimens. The influence of graphene-family material additions on microstructure was investigated, and correlated with measurements of mechanical properties. The emphasis of the research has been placed on the tribological performance conducted with the use of the ball-on-disc method under loads of 10 N and 30 N. Both the wear tracks of composites and the corresponding counterparts were carefully analysed, to evaluate the combined influence of mechanical properties and tribofilm formation on the measured wear rates. All results were compared to pure alumina as a reference specimen.

The effect of graphene-based materials: multilayer graphene (MLG), graphene oxide (GO), and nickel-coated graphene (Gn-Ni-P) addition on the mechanical properties of commercial Al2O3–ZrO2 and Al2O3–Ti(C,N) materials is discussed in this paper. The influence of used reinforcements on relative density, microstructure, hardness, and fracture toughness was investigated. Moreover, the combination of strengthening effects deriving from the addition of graphene-based materials and the presence of zirconia or carbon nitride titanium particles was analysed. In order to determine the wear resistance of the obtained composites, tribology test was conducted. The added reinforcement had an evident effect on hardness of the obtained composites in both series, an almost 150 HV5 increase was observed for the TAZ+0.2 wt%GO composites. Fracture toughness remained unchanged or decreased, which was related to the complexity of the Al2O3 + ZrO2 + Ti (CN) + Graphene Family Nanomaterials system. Moreover, an almost 800% decrease of wear rate for the TACN based composite with a 0.2 wt% addition of GO was noted. Other composites also showed an increase in wear resistance depending on the type of matrix, the type of reinforcements and the load applied during the tribology test.

This paper describes the effects of phosphorus implantation into n-type 4H-SiC substrate prior to standard dry oxidation process. Phosphorus incorporation has been reported to be one of the most efficient means of increasing SiC MOSFET field mobility however the physical basis of this phenomenon is still not clear. The aim of this research is to investigate the influence of phosphorus implantation on trap density profile close to conduction band of silicon carbide and to gain understanding of physical processes responsible for observed trap density improvement in phosphorus related oxidation technologies of silicon carbide.

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.

3C-SiC epitaxial layers were grown on on-axis (100)- and (110)-oriented silicon substrates in a RF heated horizontal hot-wall CVD reactor. We focused on the relationship between the pressure used during carbonization growth and the crystalline quality of obtained layers. A comprehensive analysis of the surface morphology of the 3C-SiC carbonization layer was performed, after which two pressure values guaranteeing top crystalline quality were determined. The carbonization layer with the lowest surface roughness was obtained at around 20 mbar, while for 30 mbar, the surface roughness was slightly worse but more homogenous. To sum up, we successfully grew 1.5 µm thick 3C-SiC layers on silicon substrates with both orientations using the said pressure conditions.

The effect of the presence of CeO2 in the source material on the properties of SiC crystals grown by Physical Vapor Transport (PVT) method is investigated. The doping efficiency and, indirectly, the presence of the cerium vapour in the growth atmosphere were examined by study of structural, electrical and optical properties of the crystals. X-ray photoelectron spectroscopy shows that Ce2O3 and CeO2 coexist on the SiC post-growth surfaces. A detectable Ce incorporation is observed only in the last grown part of the crystal.

In this work results of nitrogen doping in the amount of 0 vol.%, 3 vol.% and 10 vol.% on the growth of the 4H polytype on the 6H-SiC seed are presented. SiC crystals grown by PVT method on the (000-1) C-face of 6H seeds using the open seed backside design have been investigated. Structural and electrical properties of the crystals were studied by different experimental methods.

A good selection of growth parameters (in-situ etching, C/Si ratio, growth rate) enables obtaining of ~1nm high steps of epitaxial layers, which are comparable to the size of an elementary cell (8°off-axis) and achieve the density of BPD=8•103/cm2. Due to crystallization on substrates with low misorientation (

Polytype instability of SiC epitaxial films was the main focus of attention in the experiment performed since this factor has a decisive influence on graphene growth, which was the second stage of the experiment. Layers deposited in various initial C/Si ratios were analyzed. Our observations indicate that the initial C/Si ratio in epitaxial growth is a crucial parameter determining which polytype will be grown, in particular for cubic (3C) or hexagonal (4H) polytypes. If the initial C/Si ratio was close to its final value, the dominant polytype was 4H. On the other hand, when the initial C/Si ratio was close to zero, 3C became the major polytype in spite of a non favourable growth temperature. The results for graphene growth on an epi-SiC layer and a bulk substrate, in which case the dominant polytype was 4H, are also presented. These results indicate that layers on epitaxial 4H-SiC are thicker, more relaxed and have better quality in comparison with samples on 4H-SiC substrates. Morphology and defects in SiC epilayers were analyzed using Nomarsky optical microscopy, scanning electron microscopy (SEM) and high resolution X-ray diffraction (XRD). Graphene quality was characterized by Raman spectroscopy.

Graphene grown by a sublimation technique was studied by Scanning Electron Microscopy (SEM) and micro-Raman spectroscopy. The measurement area of a sample was marked and investigated using both systems, as a result of which SEM images were directly compared with Raman maps. In this work we show that a correlative analysis of Energy Selective Backscattered electrons detector (EsB), In-Lens figures and Raman maps of shape and intensity of the 2D band is adequate to determine graphene layer thickness with the precision of SEM and reliability of Raman spectroscopy.

This paper provides an overview of the process of 4H-SiC pn junction fabrication and characterization. The samples used in this study were fabricated in a resistively heated horizontal hot-wall Chemical Vapor Deposition reactor. The homo-epitaxial layers were grown on commercially available 4H-SiC substrates (Cree). In order to obtain p-type epilayers, they were intentionally doped with aluminum. In this work, we present our recently developed 4H-SiC pn junctions fabrication and characterization results. The ohmic contacts were formed using evaporation, etching, lift-off and high temperature annealing. Current-voltage characteristics of the devices were demonstrated.