Diamond is considered as a very promising material for the development of devices for radiation detection. Unlike other conventional photoconductive detectors diamond-based devices should provide high discrimination between UV and visible radiation. In this work we present the electro-optical properties of devices based on randomly oriented diamond films, synthesized in a microwave plasma enhanced chemical vapor deposition reactor. A comparative study on devices with coplanar interdigitated Cr/Au electrodes (with different interelectrode pitches) made of films grown simultaneously on intrinsic and p-doped silicon (100) substrates has been performed. The chemical-structural, morphological, electrical and optical properties of ROD films have been studied. In particular, the optical response has been measured in air using a Xe flash lamp coupled with an optical quartz fiber and a properly tailored front-end electronics based on a charge sensitive amplifier. Experimental results gave indications on how the device performances are dependent on the two types of employed substrates. (C) 2011 Elsevier B.V. All rights reserved.

Silicon-Carbon Nanotube radiation detectors need an electrically conductive coating layer to avoid the nanotube detachment from the silicon substrate and uniformly transmit the electric field to the entire nanotube active surface. Coating material must be transparent to the radiation of interest, and must provide the drain voltage necessary to collect charges generated by incident photons. For this purpose various materials have been tested and proposed in photodetector and photoconverter applications. In this article interface properties and electrical contact behavior of Indium Tin Oxide films on Carbon Nanotubes have been analyzed. Ion Beam Sputtering has been used to grow the transparent conductive layer on the nanotubes. The films were deposited at room temperature with Oxygen/Argon mixture into the sputtering beam, at fixed current and for different beam energies. Optical and electrical analyses have been performed on films. Surface chemical analysis and in depth profiling results obtained by X-ray Photoelectron Spectroscopy of the Indium Tin Oxide layer on nanotubes have been used to obtain the interface composition. Results have been applied in photodetectors realization based on multi wall Carbon Nanotubes on silicon.

The use of silicon and the development of micro-technology made possible the transition from macro- to micro-detection systems and of very large-scale integration systems for microelectronics. The most powerful micro-detector recently developed is the Silicon PhotoMultiplier (SiPM) that allows a pixel dimension of microns in a hundred-pixel array. The use of nanotechnology opens now a new field of applications in which materials are "built" chemically up to the desired dimensions. This process allows the realization of complex structures that have finely pixelled sub-micron dimensions and that are cheap, light, and easy to produce. Between the materials suitable for nanotechnology, carbon nanotubes (CNT) play a main role because of their facility of being produced and their unique mechanical and electrical properties. They can be grown chemically in a very easy and cheap way, assembled in the desired geometry and directly connected to readout electronics devices. In addition, they can be coupled to silicon substrates to obtain mixed micro-nano structures with intermediate electronic properties. The first radiation detector using CNTs grown through a chemical vapour deposition (CVD) process has been realized using a sapphire substrate. This device, sensitive to the radiation in the range from 220 to more than 850 nm, exhibits a relevant increase in the photocurrent toward UV wavelengths both with continuous light and with pulsed radiation. This opens the door to the realization of a new kind of low-cost radiation detector with sub-micron spatial resolution and high sensitivity in the UV radiation region. In order to avoid the large dark current observed, a new detector has been realized Using an p-doped silicon substrate. Electrical and optical properties of this novel detector have been intensively studied as well as the coupling between nanotubes and silicon. The strong matching found between the two different materials suggests the possibility of realizing a single photon detector with high quantum efficiency in the UV wavelength region. (C) 2009 Elsevier B.V. All rights reserved.

Photodetectors based on polycrystalline diamond (PCD) films are of great interest to many researchers for the attractive electronic, mechanical, optical and thermal properties. PCD films are grown using the Microwave Plasma Enhanced Chemical Vapor Deposition (MWPECVD) method. First, we characterized films by means of structural and morphological analysis (Raman spectroscopy and scanning electron microscopy), then we evaporated a pattern of coplanar interdigitated Cr/Au contacts with an inter-electrode spacing of 100 mu m in order to perform the electrical characterization. We carried out measurements of dark current and impedance spectroscopy to investigate the film properties and conduction mechanisms of films and the effects of post-growth treatments. Finally we developed a charge sensing pre-amplifier to read-out the signal produced by UV photons in the detector. (C) 2009 Elsevier B.V. All rights reserved.

Diamond is an extremely interesting material for photoemission applications, due to the negative electron affinity of its surface, which can be obtained after suitable treatments. In the present work two sets of polycrystalline diamond films, characterized by different thicknesses and deposition conditions, are analyzed. In particular, in the examined films the relationship among the grain size, the amount of non-diamond carbon (sp(2)) located at the grain boundaries and their efficiency as photocathodes has been found and carefully investigated. The photoemission yield in the UV range is evaluated for all the samples, before and after hydrogenation, and after air exposure. The crucial parameter for the photocathode performances has been found not to be the film thickness, but the properties of polycrystalline diamond films, tunable with the plasma modulation and the methane percentage in the gas mixture. (C) 2011 Elsevier B.V. All rights reserved.

A new class of radiation detectors based on carbon nanostructures as the active photosensitive element has been recently developed. In this scenario the optimization of the device, both in dark and on light irradiation, is a crucial point. Here, we report on electrical measurements performed in dark conditions on carbon nanofibers and nanotubes deposited on silicon substrates. Our experimental results were interpreted in terms of a multistep tunneling process occurring at the carbon nanostructures/silicon interface. (C) 2010 Elsevier B.V. All rights reserved.

We report on a new photodetector fabricated using carbon nanostructures grown on a silicon substrate. This device exhibits low noise, a good conversion efficiency of photons into electrical current and a good signal linearity in a wide range of radiation wavelengths ranging from ultraviolet to infrared at room temperature. The maximum quantum efficiency of 37% at 880 nm has been measured without signal amplification. Such innovative devices can be easily produced on large scales by Chemical Vapour Deposition (CVD) through a relatively inexpensive chemical process, which allows large sensitive areas from a few mm2 up to hundreds of cm2 to be covered.

A new class of nano-antimicrobials was developed by Ion Beam co-Sputtering of ZnO and polytetrafluoro_ ethylene targets. The resulting nanostructured coatings combine the antimicrobial properties of ZnO nanoparticles with the water repellence and anti-stain characters of the dispersing fluoropolymer (CFx). ZnO-CFx nanocomposites were prepared varying ZnO volume fraction (φ) in the CFx matrix by tuning the sputter- ing deposition parameters. Morphological analysis confirmed the presence of homogenously distributed ZnO nanoclusters in the polymer. ZnO loadings ranging in the 0.05-0.15 interval were explored and the nano-composites were characterized by X-ray Photoelectron Spectroscopy (XPS) to investigate their surface chemical composition. XPS spectra evidenced a high degree of polymer defluorina-tion along with the formation of ZnF2 at increasing φ valu-es. Zn speciation was performed on Zn L3M45M45 Auger signal. Coatings bioactivity was assessed against Escheri-chia coli, Staphylococcus aureus, and Kluyveromyces marxianus. At φ ≥ 0.10, ZnO-CFx composites exhibited appreciable antibacterial activity, irrespective of the target organism.

Research on the nanomaterials containing one or more transition metals is growing tremendously, thanks to the large number of preparation processes available and to the novel applications that can be envisaged in several fields. This review presents an overview of the selected studies in the field of antimicrobial textiles, employing bioactive nanophases of elements/compounds such as silver, copper, or zinc oxide. In addition, the history of use of these antimicrobials and their mechanism of action are shortly reported. Finally, a short description is provided of the deposition/preparation methods, which are being used in the authors ’ labs for the development of the textiles modified by the novel nanoantimicrobials

The realization of aSilicon Carbon Nanotube heterojuntion opens the door to a new generation of photodetectors (Si-CNT detector) based on the coupling between this two materials. In particular the growth of Multiwall Carbon Nanotubes on the surface of a n-doped silicon substrate results on a Schottky diode junction with precise rectifying characteristics. The obtained device presents a low dark current, high efficiency in the photoresponsivity, high linearity and a wide stability range. The junction barrier is about 3.5 V in reverse polarity with a breakdown limit at more than 100 V. The spectral behavior reflects the silicon spectral range with a maximum at about 880 nm

In this paper a study of Multi Wall Carbon Nanotube films deposited at low temperature by means of a spray technique on different substrates is presented. Nanodispersion of nanotube powder in a non-polar 1,2-dichloroethane solvent was used as starting solution. Electron Microscopy in Scanning and Transmission modes were used in order to verify the morphological properties of the deposited films. Visible light detectors were prepared spraying Multi Wall Carbon Nanotubes on silicon substrates with different layouts. In some detectors the nanotubes were covered by an Indium Tin Oxide (ITO) layer. Electrical measurements, both in dark and under light irradiation, were performed and Current-Voltage characteristics are reported. The Indium Tin Oxide coating effect on the photoconductivity yield is presented and discussed along with device ageing test, resulting in a very good photoconduction and stability over four months.

Method for the production of high efficiency photocathodes for ultraviolet based on nanodiamonds