Papers by Nicoletta Baldini
Archivio Storico Italiano, 2012
E MARMI ANTICHI» le viceNde della collezioNe di opere d'arte di GiorGio vasari attraverso Nuovi d... more E MARMI ANTICHI» le viceNde della collezioNe di opere d'arte di GiorGio vasari attraverso Nuovi documeNti d'archivio *
Surface and Coatings Technology, 2013
Diamond and Related Materials, 2010
Enhanced nucleation behavior for ultra-nanocrystalline diamond on Si-substrates via the utilizati... more Enhanced nucleation behavior for ultra-nanocrystalline diamond on Si-substrates via the utilization of Mo-coating was observed. Spectroscopic examinations indicated that the mechanism of enhancement is the formation of Mo 2 C phase, which hindered the inward diffusion of carbon species into the substrate materials. The diamonds may either nucleate directly on Mo 2 C-layer or via the formation of transition phases, the graphite. The incoming carbons may also react with Mo 2 C phase to form MoC phase or form the graphite phase prior to the induction of diamond nuclei. In all cases, the carbons accumulated rapidly due the presence of a Mo 2 C (or MoC) layer, triggering the formation of diamond nuclei.
Journal of Applied Physics, 2002
An infrared photodetector that contains a superlattice structure and a blocking barrier was inves... more An infrared photodetector that contains a superlattice structure and a blocking barrier was investigated. The photodetector shows advantages including a low operating voltage ͑Ͻ0.7 V͒, wide detection bandwidth, flexible miniband engineering, and in particular, voltage-tunable spectral responsivity. The blocking barrier not only prohibits the dark current but also acts as a high-pass energy filter to tune the spectral responsivity. The zero background peak detectivity of our detector is 3.7ϫ10 9 cm Hz 0.5 /W ͑9.7 m͒ at Ϫ0.5 V and 2.2ϫ10 10 cm Hz 0.5 /W ͑6.7 m͒ at Ϫ0.1 V. Since the spectral responsivity at different biases is independent, temperature sensing is feasible by taking the ratio of the measured photocurrent at different biases. A demonstration of temperature sensing by using our superlattice infrared photodetector with a blocking barrier is also shown in this article. Those results show the superlattice is a simple and efficient structure for the design of a multicolor infrared photodetector.
Science of Advanced Materials, 2013
ABSTRACT The diamond nanowires (DNW) films have been deposited by N2-based microwave plasma enhan... more ABSTRACT The diamond nanowires (DNW) films have been deposited by N2-based microwave plasma enhanced chemical vapor deposition. Hydrogen plasma treatment is carried out on these films for various treatment times which result in microstructural and chemical modification. Morphology of as-grown DNW films resemble symmetry of dense grains composed in nanowires; however the wires break into ultrasmall, randomly distributed spherical shaped grains after 15 minutes of H2 plasma treatment. Transmission electron microscopy depicts that as-grown DNW films mainly consist of diamond nanocrystals with graphitic sp2C—C bonded grain boundaries. However, the graphitic grain boundaries do not exist after H2 plasma treatment on DNW films. Raman spectroscopy and near edge X-ray absorption fine structure spectroscopy studies reveal that after H2 plasma treatment the films possess large fraction of sp3 C—C and C—H bonding in the form of trans-polyacetylene symmetry of sp2 CH x . Interestingly, the friction coefficient of 0.0001 is obtained for the 15 minutes H2 plasma treated DNW films. Such an extent of low valued friction coefficient is described by the passivation of uncompensated carbon dangling bonds by hydrogen content and adsorption of H2 O molecules. Furthermore, in low humid atmosphere, the friction coefficient is found to be consistently increased which confirms the insufficient chemical passivation of carbon dangling bonds.
Journal of Applied Physics, 2013
Microstructural evolution of ultrananocrystalline diamond (UNCD) films as a function of substrate... more Microstructural evolution of ultrananocrystalline diamond (UNCD) films as a function of substrate temperature (T S) and/or by introducing H 2 in Ar/CH 4 plasma is investigated. Variation of the sp 2 and sp 3 carbon content is analyzed using UV-Raman and near-edge X-ray absorption fine structure spectra. Morphological and microstructural studies confirm that films deposited using Ar/CH 4 plasma at low T S consist of a random distribution of spherically shaped ultra-nano diamond grains with distinct sp 2-bonded grain boundaries, which are attributed to the adherence of CH radicals to the nano-sized diamond clusters. By increasing T S , adhering efficiency of CH radicals to the diamond lattice drops and trans-polyacetylene (t-PA) encapsulating the nano-sized diamond grains break, whereas the addition of 1.5% H 2 in Ar/CH 4 plasma at low T S induces atomic hydrogen that preferentially etches out the t-PA attached to ultra-nano diamond grains. Both cases make the sp 3-diamond phase less passivated. This leads to C 2 radicals attaching to the diamond lattice promoting elongated clustered grains along with a complicated defect structure. Such a grain growth model is highly correlated to explain the technologically important functional property, namely, plasma illumination (PI) of UNCD films. Superior PI properties, viz. low threshold field of 0.21 V/lm with a high PI current density of 4.10 mA/cm 2 (at an applied field of 0.25 V/lm) and high c-coefficient (0.2604) are observed for the UNCD films possessing ultra-nano grains with a large fraction of grain boundary phases. The grain boundary component consists of a large amount of sp 2-carbon phases that possibly form interconnected paths for facilitating the transport of electrons and the electron field emission process that markedly enhance PI properties.
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Papers by Nicoletta Baldini