Vesna Borjanović

Comparative studies of EFG poly-Si grown by different procedures

The impurity content in EFG polycrystalline silicon materials grown by different procedures from graphite and quartz crucible has been extensively studied using Fourier transform IR technique. It is shown that the oxygen content in the material is much more dependent on the growth atmosphere at meniscus than on the type of crucible. In all samples the carbon content remains supersaturated up to very high temperatures of annealing, not affected by the oxygen presence.

Influence of proton irradiation on the structure and stability of poly(dimethylsiloxane) and poly(dimethylsiloxane)-nanodiamond composite

In the present study, pure poly(dimethylsiloxane) (PDMS) polymer and PDMS-detonation nanodiamond (PDMS-DND) composite with 1wt.% of DND were irradiated under vacuum at room temperature with a 2MeV proton beam with fluences in the 1013–1015cm−2 range. Modification of the structures and properties of the pure polymer and the nanocomposite material were monitored as a function of proton fluence. Specifically, the vibrational dynamics of pure PDMS and PDMS-DND nanocomposites, both unirradiated and irradiated samples, were investigated using Raman and Fourier transform infrared spectroscopy (FTIR). The Raman and FTIR spectra of the PDMS and PDMS-DND composites exhibit an overall reduction in intensity of all vibrational bands of the irradiated samples. The changes in relative intensities of the characteristic vibrational bands as a function of irradiation fluence indicate that cleavage of the backbone (Si–O–Si) PDMS chains was most pronounced. Importantly, structural degradation of PDMS-DND composites takes pl...

Polymer nanocomposites with improved resistance to ionizing radiation

Polymer nanocomposites with improved resistance to high energy ionizing radiation. Certain embodiments involve methods for providing a nanocomposite material with resistance to high energy ionizing radiation using nanodiamond, zinc oxide and mixtures of these nanoparticles with other nanoparticles dispersed within the matrix. Other embodiments relate to methods of delivering and dispersing the nanoparticles through the material or a surface layer. Other embodiments include methods of forming chemical bonds between the nanoparticles and the material. This abstract is not to be considered limiting, since other embodiments may deviate from the features described in this abstract.

Quantitative analysis of a-Si1-xCx:H thin films

Abstract The composition of a-Si 1− x C x :H films, deposited by magnetron sputtering, was measured by AES (Auger Electron Spectroscopy), RBS (Rutherford Backscattering Spectrometry) using both, protons and α-particles, ERDA (Elastic Recoil Detection Analysis) and FTIR spectroscopy. The results obtained by all three methods show agreement in C C / C Si ratio within the experimental error. However, the AES somewhat underestimates the silicon concentrations, which is discussed as a consequence of chemical bonding and matrix effects. The hydrogen concentrations obtained by ERDA are typically about 30% higher than those estimated by FTIR, possibly due to the presence of non-bonded hydrogen in the film.

DIELECTRIC PROPERTIES OF ANNEALED ONION-LIKE CARBON COMPOSITES IN MICROWAVE REGION

The onion-like carbon composites prepared according to different technologies were studied by means of broadband dielectric/electric spectroscopy in a wide temperature range from 300 to 450 K. The value of complex dielectric permittivity of composites strongly increases after annealing. From complex dielectric spectra, complex impedance spectra and distribution of relaxation times were calculated. After annealing of composites on cooling the asymmetricity of distribution of relaxation times strongly increases. Annealed composites exhibit only a weak temperature dependence of microwave properties and are promising candidates for electromagnetic shielding materials.

Defects in polycrystalline silicon studied by IBICC

In the research of semiconducting materials, ion beam-induced charge collection (IBICC) technique can provide interesting and straightforward information about the different electronic device characteristics. This nuclear microprobe technique was used for the qualitative analysis of charge collection efficiency spatial distribution in three different types of EFG silicon material. Using IBICC technique, we studied the influence of present light impurities (oxygen, carbon) on electrical activity of extended defects. It is shown that oxygen segregating close to structural defects influences their electrical activity, while for carbon we did not observe the same effect. We demonstrated that IBICC technique could be applied to provide spatial information about the position of electrically active defects, and/or their activation or deactivation during subsequent processing.

Nanodiamond Particles in Electronic and Optical Applications

Current use of nanodiamond (ND) particles in electronic-related applications is mostly restricted to their role in seeding of substrates for growth of diamond films by chemical vapor deposition (CVD). While it is a niche application, nanometer-sized diamond particles are indispensable in this role. Seeding of substrates using a novel slurry of detonation nanodiamond particles in dimethylsulfoxide (DMSO) and methanol is one of the topics of this article. At the same time, optical applications of NDs, particularly development of photoluminescent NDs for biomedical applications is one of the most popular current research topics. In this paper perspectives for the use of detonation NDs and specifically the role of surface functionalization in imparting photoluminescent properties to detonation NDs as well as enhanced photoluminescence of proton irradiated ND-polydimethylsiloxane composites are discussed.

IBIC studies of structural defect activity in different polycrystalline silicon material

In the research of semiconducting materials, the ion beam induced charge collection (IBIC) technique can provide interesting and straightforward information about the different electronic device characteristics. This nuclear microprobe technique was used for the qualitative analysis of the spatial distribution of charge collection efficiency in several types of poly-Si material. We studied the influence of light impurities (oxygen, carbon) on electrical activity of extended defects. It is shown that oxygen segregating close to structural defects influences their electrical activity, while for carbon we did not observe the same effect. We demonstrated that IBIC can be applied to provide spatial information about the position of electrically active defects and its activation during subsequent processing.

Preparation of the Kondo Insulators FeSi by Magnetron Sputtering

The Kondo insulator FeSi was prepared by DC magnetron sputtering and the effects of sputtering parameters on the formation of FeSi were investigated in detail. The formation of monosilicide FeSi was clarified using X-ray diffraction (XRD) and its microstructure was characterized by scanning electron microscopy (SEM). The results indicate that the sputtering gas pressure, the sputtering power and the Ar flux all have significantly effects on formation of FeSi and the crystalline of the film. The sputtering gas pressure has effects on sputtering yields, depositing rate and the energy of sputtering atoms, the sputtering power has effects on the kinetic energy and the diffusion ability of deposing atoms and the gas flux has the effects on the flowing state of Ar gas. The most optimal sputtering parameters for the preparation of the Kondo insulator FeSi by DC magnetron sputtering are given: 1.5 Pa for sputtering Ar pressure, 100 W for sputtering power and 20 SCCM for sputtering Ar flux.