ABSTRACT
The outstanding properties of graphene, a single graphite layer, render it a top candidate for substituting silicon in future electronic devices. The so far exploited synthesis approaches, however, require conditions typically achieved in specialized laboratories and result in graphene sheets whose electronic properties are often altered by interactions with substrate materials. The development of graphene-based technologies requires an economical fabrication method compatible with mass production. Here we demonstrate for the fist time the feasibility of graphene synthesis on commercially available cubic SiC/Si substrates of >300 mm in diameter, which result in graphene flakes electronically decoupled from the substrate. After optimization of the preparation procedure, the proposed synthesis method can represent a further big step toward graphene-based electronic technologies.
Subject(s)
Carbon Compounds, Inorganic/chemistry , Crystallization/methods , Electronics/instrumentation , Graphite/chemistry , Nanostructures/chemistry , Nanostructures/ultrastructure , Silicon Compounds/chemistry , Silicon/chemistry , Electric Conductivity , Equipment Design , Equipment Failure Analysis , Macromolecular Substances/chemistry , Materials Testing , Molecular Conformation , Nanotechnology/methods , Particle Size , Surface PropertiesABSTRACT
The main focus of this paper is the description of qualitatively new facilities for diagnostics of biological and medical objects and medical therapy obtained by applications of nanocrystalline scintillators. These facilities are based on abilities of nanoscintillators to selective conjugation with various biomolecular objects and noticeable variations of their atomic structures, X-ray diffraction (XRD) patterns, and light-emission characteristics induced by modifications of conditions on their external surfaces. Experimental results presented in this paper provide development of detection in vivo just inside a living organism of various viruses, cancer cells, and other pathological macromolecules by means of scanning X-ray diffractometry of nanoparticles introduced into the body. These data are produced by selective adsorption of pathological bioobjects by these nanoparticles and subsequent modifications of their XRD patterns. Application of narrow collimated X-ray beams and new types of X-ray detector matrices providing microscopic spatial resolution due to usage of nanoscintillators enables determination of the regions where these pathologies are localized with high accuracy. The procedure of detection of pathological organelles by this method improves possibilities for effective destruction of these pathologies by low-dose X-ray irradiation of the places of their localization. High effectiveness of this X-ray destruction is provided by concentrated absorption of X-ray quanta by the nanoscintillators and direct transfer of the absorbed energy to the pathological objects that are attached to the absorbing particles. Constructions of 3-D radiation detector matrices providing necessary microscopic spatial and angular resolutions of X-ray imaging are described on the basis of nanoscintillators, fiber light guides, and microcapillary matrices.
