Silvia Orlanducci | Università di Roma Tor Vergata (original) (raw)
Uploads
Papers by Silvia Orlanducci
Deposits of individual diamond grains and continuous polycrystalline diamond layers have been gen... more Deposits of individual diamond grains and continuous polycrystalline diamond layers have been generated by means of a HFCVD technique onto different types of untreated or seeded NbN surfaces. To test the feasibility of using diamond layers as protective coatings for aerospace applications, we carried out diamond deposition onto the lithographically defined NbN microelectrodes of a NbN/SiO2 multifinger device. The morphological and structural features of the diamond deposits and of the substrates were characterized by FE-SEM, XRD and Raman spectroscopy. The preferential growth of diamond on the superconductive NbN enables the selective coating of the NbN microstripes sputtered on the insulating SiO2. Moreover the diamond coating procedure is able to preserve the structural integrity of the substrate material and to retain the shaped architecture of the device. For the polycrystalline diamond layers grown on NbN a residual stress of -9.8 GPa, largely due to thermal stress, has been estimated by Raman analysis. The diamond coatings of the NbN-based architectures result to be mechanically stable.
Acta Crystallographica Section A Foundations of Crystallography, 2005
Current development in miniature optical components leads to extensive study of single crystal la... more Current development in miniature optical components leads to extensive study of single crystal layers because of a number additional benefits such as ability to use materials with high doping levels or to obtain high gain with modest pump powers. New crystals of solid solutions based on the YAl 3 (BO 3) 4-RAl 3 (BO 3) 4 (YAB-RAB) systems are promising solids for self-frequency doubling lasers [1]. In this report, our recent results on liquid-phase epitaxy (LPE) of RAB and R:YAB single crystal layers are discussed. Variations of growth rates of these layers were determined, in order to control crystal growth mechanism. Relations between the growth rate V and relative supersaturation were found. It is also shown that primarily volume and surface processes occur simultaneously although evidence is presented for kinetic limitation of the growth rate on the later stage. Besides, growth spirals epilayers frequently exhibit irregularities such as cusps and corrugations, but flat areas may also present on the surface. Micromorphological features as well as growth kinetics greatly depend on the substrate perfection.
Nanoscience and Nanotechnology Letters, 2013
ABSTRACT Arrays of conical-shaped nanodiamond structures are formed on silicon substrate by a sin... more ABSTRACT Arrays of conical-shaped nanodiamond structures are formed on silicon substrate by a single-step CVD process from CH4/H2 mixtures. The formation of these nanocones has been found to depend on interplay between growing and etching during the CVD process carried out in a dual-mode MW/RF plasma reactor. Morphology and structure of the conical-like systems can be controlled by varying the process parameters, and have been investigated by scanning electron microscopy (SEM), reflection high energy electron diffraction (RHEED) and micro-Raman spectroscopy. The Field Emission (FE) properties of different diamond nanocones arrays have been investigated and compared with those of analogous systems in order to assess the feasibility of the present nanomaterials as electron emitters for cold cathodes. The FE behavior is discussed taking into account the structure of the different diamond nanocones.
We investigated the influence of both electrolyte nature and concentration on the kinetics of ele... more We investigated the influence of both electrolyte nature and concentration on the kinetics of electropolymerization of several monomers and on the resulting morphology of the produced nanotubules. The investigated monomers were: 1,2- and 1,4-diaminobenzene, 2,3- and 1,8-diaminonaphthalene, o-anisidine. Finally, the morphology and structure of the different template-synthesized nanostructured materials has been carefully analyzed by scanning electron microscopy (SEM) and Raman
Chemical Physics Letters, 2012
ABSTRACT We studied the coupling of diamond Si color centers with size-controlled Au nanoparticle... more ABSTRACT We studied the coupling of diamond Si color centers with size-controlled Au nanoparticles obtained by chemical routes. The diamond samples, synthesized by Chemical Vapor Deposition, were polycrystalline films or isolated grains. The plasmonic responses of the Au nanoparticles were found to couple with the Ar+ laser frequency or with the frequency of the Si-defects photoluminescence (PL). When the PL of Si optical centers is resonant with the maximum of the Au extinction spectrum, a threshold behavior and a decrease of the PL band FWHM with increasing laser energy is detected, suggesting the transition from spontaneous to stimulated emission.
Carbon, 2005
The preparation and electrical characterization of a new class of composite layers formed by disp... more The preparation and electrical characterization of a new class of composite layers formed by dispersing single-walled carbon nanotubes (SWNT) in 1,8-diaminonaphthalene polymer, the poly(1,8-DAN), are described.
We demonstrate efficient NH 3 detection in single wall carbon nanotubes (SWCNT) ordered by mean o... more We demonstrate efficient NH 3 detection in single wall carbon nanotubes (SWCNT) ordered by mean of dielectrophoretical process. The employed approach was to disperse the nanotubes, treated following a specific protocol, in CHCl 3 and to distribute the suspension between the tracks of multifinger Au electrodes (40 m spacing) on SiO 2 /Si substrates. The control of arrangement and alignment of the SWCNT bundles was achieved by applying an alternate voltage (frequency 1 MHz, 10 V pp ) during the solvent evaporation. The sensitivity for NH 3 detection resulted to be strongly enhanced by the degree of SWCNT alignment between the electrodes. The sensitivity resulted enhanced also by increasing up to 80 • C the temperature of the devices. We investigated also the effect induced on the NH 3 absorption/desorption processes by a gate voltage applied to the Si substrate beneath the interdigitated electrodes on the NH 3 . The results indicate that the sensitivity of the SWCNT-based sensor can be increased applying a negative gate voltage.
Applied Physics Letters, 2009
... In particular, the grain boundaries can influence the emission properties of micro e nanostru... more ... In particular, the grain boundaries can influence the emission properties of micro e nanostructured diamond films. ... applications for such robust electron sources include industrial welders and space operations (thrusters, tethers), but also the use as injectors in plasma ...
Miniaturized gas-sensing devices that use single-walled carbon nanotubes as active material have ... more Miniaturized gas-sensing devices that use single-walled carbon nanotubes as active material have been fabricated using two different electrode materials, namely, Au/Cr and NbN. The resistive sensors have been assembled aligning by dielectrophoresis the nanotube bundles between 40 µm spaced Au/Cr or NbN multifinger electrodes. The sensing devices have been tested for detection of the H 2 S gas, in the concentration range 10-100 ppm, using N 2 as carrier gas. No resistance changes were detected using sensor fabricated with NbN electrodes, whereas the response of the sensor fabricated with Au/Cr electrodes was characterized by an increase of the resistance upon gas exposure. The main performances of this sensor are a detection limit for H 2 S of 10 ppm and a recovery time of few minutes. The present study suggests that the mechanism involved in H 2 S gas detection is not a direct charge transfer between molecules and nanotubes. The hypothesis is that detection occurs through passivation of the Au surfaces by H 2 S molecules and modification of the contact resistance at the Au/nanotube interface.
ABSTRACT The exceptional structural, mechanical, chemical and electronic properties of single-wal... more ABSTRACT The exceptional structural, mechanical, chemical and electronic properties of single-wall carbon nanotubes (SWCNTs) make them suitable for the development of a completely new class of sensors and actuators, biosensors, electrochemical capacitors and supercapacitors. As a result, the study of CNT-based nanostructured and functional materials has become an interesting theme. In particular, the formation of CNT/polymer composites, besides possible improvements in the mechanical and electrical properties of polymers, is considered as a promising approach for the assembling of hybrid CNTs-polymer devices. However, manipulation and processing of SWCNTs is generally limited by their insolubility in most common solvents. Considerable effort has therefore been devoted to the chemical modification and derivation of carbon nanotubes. In this work, we described different treatments of carbon nanotube materials and a FT-IR study to demonstrate the functionalization of SWCNTs.
4th IEEE Conference on Nanotechnology, 2004., 2004
'Francesca Brunetti, 'Pietro Regoliosi, 'Andrea Reale, 'Aldo Di Carlo, *Maria... more 'Francesca Brunetti, 'Pietro Regoliosi, 'Andrea Reale, 'Aldo Di Carlo, *Maria Letizia Terranova, 'S. Orlanducci, 'Angelamaria Fiori, 'Emanuela Tambuni, *%to Sessa, 'Alessandro Ciorba, 'Marc0 Rossi, 4Matteo Cirillo, 4Vitt0ri0 Merlo. ... 'Dept. of Electronic Engineering, ...
Deposits of individual diamond grains and continuous polycrystalline diamond layers have been gen... more Deposits of individual diamond grains and continuous polycrystalline diamond layers have been generated by means of a HFCVD technique onto different types of untreated or seeded NbN surfaces. To test the feasibility of using diamond layers as protective coatings for aerospace applications, we carried out diamond deposition onto the lithographically defined NbN microelectrodes of a NbN/SiO2 multifinger device. The morphological and structural features of the diamond deposits and of the substrates were characterized by FE-SEM, XRD and Raman spectroscopy. The preferential growth of diamond on the superconductive NbN enables the selective coating of the NbN microstripes sputtered on the insulating SiO2. Moreover the diamond coating procedure is able to preserve the structural integrity of the substrate material and to retain the shaped architecture of the device. For the polycrystalline diamond layers grown on NbN a residual stress of -9.8 GPa, largely due to thermal stress, has been estimated by Raman analysis. The diamond coatings of the NbN-based architectures result to be mechanically stable.
Acta Crystallographica Section A Foundations of Crystallography, 2005
Current development in miniature optical components leads to extensive study of single crystal la... more Current development in miniature optical components leads to extensive study of single crystal layers because of a number additional benefits such as ability to use materials with high doping levels or to obtain high gain with modest pump powers. New crystals of solid solutions based on the YAl 3 (BO 3) 4-RAl 3 (BO 3) 4 (YAB-RAB) systems are promising solids for self-frequency doubling lasers [1]. In this report, our recent results on liquid-phase epitaxy (LPE) of RAB and R:YAB single crystal layers are discussed. Variations of growth rates of these layers were determined, in order to control crystal growth mechanism. Relations between the growth rate V and relative supersaturation were found. It is also shown that primarily volume and surface processes occur simultaneously although evidence is presented for kinetic limitation of the growth rate on the later stage. Besides, growth spirals epilayers frequently exhibit irregularities such as cusps and corrugations, but flat areas may also present on the surface. Micromorphological features as well as growth kinetics greatly depend on the substrate perfection.
Nanoscience and Nanotechnology Letters, 2013
ABSTRACT Arrays of conical-shaped nanodiamond structures are formed on silicon substrate by a sin... more ABSTRACT Arrays of conical-shaped nanodiamond structures are formed on silicon substrate by a single-step CVD process from CH4/H2 mixtures. The formation of these nanocones has been found to depend on interplay between growing and etching during the CVD process carried out in a dual-mode MW/RF plasma reactor. Morphology and structure of the conical-like systems can be controlled by varying the process parameters, and have been investigated by scanning electron microscopy (SEM), reflection high energy electron diffraction (RHEED) and micro-Raman spectroscopy. The Field Emission (FE) properties of different diamond nanocones arrays have been investigated and compared with those of analogous systems in order to assess the feasibility of the present nanomaterials as electron emitters for cold cathodes. The FE behavior is discussed taking into account the structure of the different diamond nanocones.
We investigated the influence of both electrolyte nature and concentration on the kinetics of ele... more We investigated the influence of both electrolyte nature and concentration on the kinetics of electropolymerization of several monomers and on the resulting morphology of the produced nanotubules. The investigated monomers were: 1,2- and 1,4-diaminobenzene, 2,3- and 1,8-diaminonaphthalene, o-anisidine. Finally, the morphology and structure of the different template-synthesized nanostructured materials has been carefully analyzed by scanning electron microscopy (SEM) and Raman
Chemical Physics Letters, 2012
ABSTRACT We studied the coupling of diamond Si color centers with size-controlled Au nanoparticle... more ABSTRACT We studied the coupling of diamond Si color centers with size-controlled Au nanoparticles obtained by chemical routes. The diamond samples, synthesized by Chemical Vapor Deposition, were polycrystalline films or isolated grains. The plasmonic responses of the Au nanoparticles were found to couple with the Ar+ laser frequency or with the frequency of the Si-defects photoluminescence (PL). When the PL of Si optical centers is resonant with the maximum of the Au extinction spectrum, a threshold behavior and a decrease of the PL band FWHM with increasing laser energy is detected, suggesting the transition from spontaneous to stimulated emission.
Carbon, 2005
The preparation and electrical characterization of a new class of composite layers formed by disp... more The preparation and electrical characterization of a new class of composite layers formed by dispersing single-walled carbon nanotubes (SWNT) in 1,8-diaminonaphthalene polymer, the poly(1,8-DAN), are described.
We demonstrate efficient NH 3 detection in single wall carbon nanotubes (SWCNT) ordered by mean o... more We demonstrate efficient NH 3 detection in single wall carbon nanotubes (SWCNT) ordered by mean of dielectrophoretical process. The employed approach was to disperse the nanotubes, treated following a specific protocol, in CHCl 3 and to distribute the suspension between the tracks of multifinger Au electrodes (40 m spacing) on SiO 2 /Si substrates. The control of arrangement and alignment of the SWCNT bundles was achieved by applying an alternate voltage (frequency 1 MHz, 10 V pp ) during the solvent evaporation. The sensitivity for NH 3 detection resulted to be strongly enhanced by the degree of SWCNT alignment between the electrodes. The sensitivity resulted enhanced also by increasing up to 80 • C the temperature of the devices. We investigated also the effect induced on the NH 3 absorption/desorption processes by a gate voltage applied to the Si substrate beneath the interdigitated electrodes on the NH 3 . The results indicate that the sensitivity of the SWCNT-based sensor can be increased applying a negative gate voltage.
Applied Physics Letters, 2009
... In particular, the grain boundaries can influence the emission properties of micro e nanostru... more ... In particular, the grain boundaries can influence the emission properties of micro e nanostructured diamond films. ... applications for such robust electron sources include industrial welders and space operations (thrusters, tethers), but also the use as injectors in plasma ...
Miniaturized gas-sensing devices that use single-walled carbon nanotubes as active material have ... more Miniaturized gas-sensing devices that use single-walled carbon nanotubes as active material have been fabricated using two different electrode materials, namely, Au/Cr and NbN. The resistive sensors have been assembled aligning by dielectrophoresis the nanotube bundles between 40 µm spaced Au/Cr or NbN multifinger electrodes. The sensing devices have been tested for detection of the H 2 S gas, in the concentration range 10-100 ppm, using N 2 as carrier gas. No resistance changes were detected using sensor fabricated with NbN electrodes, whereas the response of the sensor fabricated with Au/Cr electrodes was characterized by an increase of the resistance upon gas exposure. The main performances of this sensor are a detection limit for H 2 S of 10 ppm and a recovery time of few minutes. The present study suggests that the mechanism involved in H 2 S gas detection is not a direct charge transfer between molecules and nanotubes. The hypothesis is that detection occurs through passivation of the Au surfaces by H 2 S molecules and modification of the contact resistance at the Au/nanotube interface.
ABSTRACT The exceptional structural, mechanical, chemical and electronic properties of single-wal... more ABSTRACT The exceptional structural, mechanical, chemical and electronic properties of single-wall carbon nanotubes (SWCNTs) make them suitable for the development of a completely new class of sensors and actuators, biosensors, electrochemical capacitors and supercapacitors. As a result, the study of CNT-based nanostructured and functional materials has become an interesting theme. In particular, the formation of CNT/polymer composites, besides possible improvements in the mechanical and electrical properties of polymers, is considered as a promising approach for the assembling of hybrid CNTs-polymer devices. However, manipulation and processing of SWCNTs is generally limited by their insolubility in most common solvents. Considerable effort has therefore been devoted to the chemical modification and derivation of carbon nanotubes. In this work, we described different treatments of carbon nanotube materials and a FT-IR study to demonstrate the functionalization of SWCNTs.
4th IEEE Conference on Nanotechnology, 2004., 2004
'Francesca Brunetti, 'Pietro Regoliosi, 'Andrea Reale, 'Aldo Di Carlo, *Maria... more 'Francesca Brunetti, 'Pietro Regoliosi, 'Andrea Reale, 'Aldo Di Carlo, *Maria Letizia Terranova, 'S. Orlanducci, 'Angelamaria Fiori, 'Emanuela Tambuni, *%to Sessa, 'Alessandro Ciorba, 'Marc0 Rossi, 4Matteo Cirillo, 4Vitt0ri0 Merlo. ... 'Dept. of Electronic Engineering, ...