We report geometry, energy, and some electronic properties of [n,4]- and [n,5]prismanes (polyprismanes): a special type of carbon nanotubes constructed from dehydrogenated cycloalkane C4- and C5-rings, respectively. Binding energies, interatomic bonds, and the energy gaps between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) have been calculated using density functional approach and nonorthogonal tight-binding model for the systems up to thirty layers. It is found that polyprismanes become more thermodynamically stable as their effective length increases. Moreover, they may possess semiconducting properties in the bulk limit.

In this article we present the results of micro-Raman studies of graphene grown on copper foil surface by atmospheric pressure CVD using decane as precursor, nitrogen as carrier gas with zero flow of hydrogen. Analysis of Raman spectroscopy data showed that film contains spots with single layer thick graphene. We observed significant blue shift of 2D and G bands positions for mono-atomically thick graphene on copper foil. Following literature we relate this shift to the strain induced by the presence of copper substrate. Moreover, we observed changes in the defectiveness of graphene layers after the transfer, which was related to the appearance of chemically-induced defects and defects induced by changes in the mechanical strain.

The results of quantum mechanical calculations of elementary prismanes-hexaprismane C 12 H 12 and octaprismane C 16 H 16 -have been presented. Their stability has been investigated in terms of the density functional theory and nonorthogonal tight binding model, and the heights of potential barriers pre venting isomerization and decay have been determined. It has been established based on the analysis of the molecular dynamics data and the hypersurface of the potential energy of these metastable compounds that hexaprismane and octaprismane have a rather high kinetic stability, which indicates the possibility of the for mation of carbon polyprismanes for applications in microelectronics and nanoelectronics, power engineer ing, pharmaceutics, metrology, and information technologies.

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Abstract. This paper is dedicated to the experimental investigation of Ohmic contacts to the n + -doped region of AlGaN/GaN transistor heterostructure based on Ti/Si/Ti/Al/Ni/Au metallization. Effect of annealing temperature on the specific resistance of Ohmic contact was studied. Ohmic contact with the resistance of 3.4·10 -6 Ω·cm 2 was formed by optimization of the annealing temperature and introduction of the additional doping silicon layer.

Near-interfacial oxide traps and chemical impurities on the graphene surface or at the graphene-dielectric interface can be a source of intentional or unintentional doping of graphene sheet. The efficiency of such chemical doping can vary in a wide range depending on parameters of graphene field effect devices. Mechanisms of such sensitivity of doping efficiency to the device characteristics need to be understood. The objective of this paper is to theoretically derive the analytical relations, adapted to the explicit calculation of graphene chemical doping.

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