L. Schiavulli | Università degli Studi di Bari (original) (raw)
Papers by L. Schiavulli
Journal of Non-Crystalline Solids, 1992
... Non-Crystalline Solids 139 (1992) 60-66 ;OVRNA L Or North-Holland NON-CRYSTALLINE SOLIDS Urba... more ... Non-Crystalline Solids 139 (1992) 60-66 ;OVRNA L Or North-Holland NON-CRYSTALLINE SOLIDS Urbach tail in amorphous gallium arsenide films Roberto Murri, Luigi Schiavulli, NicolaPinto and Teresa ... [5\] R. Murri, F. Gozzo, N. Pinto, L. Schiavulli, C. De Blasi and ...
Solid-State Electronics, 2005
The use of GaN as an alternative interlayer for stable passivation of gallium arsenide surface is... more The use of GaN as an alternative interlayer for stable passivation of gallium arsenide surface is investigated. To this aim remote N 2 -H 2 plasma nitridation of the n-doped gallium arsenide surface has been performed. The exposure time to N 2 -H 2 plasmas has been varied in order to form ultrathin GaN layers with different thickness. Gallium nitride layer thickness and composition analysis have been determined by in situ spectroscopic ellipsometry. The changes of the electronic properties of GaAs surface induced by nitridation process have been studied by means of DC and AC electrical characterizations on Schottky barrier diodes tailored on gallium nitride/gallium arsenide structure. The evidence of achievement of GaAs surface electronic passivation under short time plasma treatment will be provided.
InP films have been deposited on amorphous sapphire substrate by means of the metallorganic chemi... more InP films have been deposited on amorphous sapphire substrate by means of the metallorganic chemical vapour deposition technique with and without PH3/H2 plasma preactivation. Polycrystalline materials, having average grain sizes of about 40 nm, which, however, vary according to the growth parameters, were obtained. The structural and compositional disorder strongly influence the optical and electrical properties. The most structurally disordered films present the largest photoluminescence (PL) efficiency and a blue-shift of the whole PL spectra. Radiative recombinations of carriers confined in crystallites having the smallest sizes are proposed to explain such an anomalous behaviour. The temperature dependence of the bandgap follows the well known phenomenological models except for the hydrogenated samples, in which a blue-shift of the intrinsic luminescence band is observed with increasing temperature. This anomalous effect is related to phonon-assisted transitions between nanoclusters with different sizes. Electrical conductivity measurements show different conductivity mechanisms in two different ranges of temperature. In particular, for temperatures lower than 200 K the conduction mechanism is due to a variable-range hopping process.
Thin Solid Films, 2006
A study of the structural, optical and electrical properties of synthetic and natural melanin by ... more A study of the structural, optical and electrical properties of synthetic and natural melanin by means of X-ray diffraction, absorption and photocurrent techniques is reported. The model of the natural melanin film as a network of nano-aggregates of polymeric units based on the indolic structure is proposed to explain the X-ray diffraction results. The shape of the absorption spectra is
Applied Surface Science, 2004
Journal of Luminescence, 2003
The passivation of GaAs (1 0 0) surface has been performed by using remote N 2 -H 2 (3% in H 2 ) ... more The passivation of GaAs (1 0 0) surface has been performed by using remote N 2 -H 2 (3% in H 2 ) RF plasma nitridation. The samples, consisting of n-doped GaAs wafers, show photoluminescence enhancement when the nitridation time and exposure to the plasma are in a narrow temporal window, so that a very thin (about 10 ( A) GaN layer is deposited on the GaAs surface. Pure N 2 nitridation does not provide an efficient passivation, because it results in GaN layers with As and AsN x segregation at the GaN/GaAs interface. Increase of Au-GaAs Schottky barrier with the insertion of GaN interlayer and improvement of current-voltage characteristic have been observed. r
Thin Solid Films, 2001
Page 1. Jpn. J. Appl. Phys. Vol. 38 (1999) pp. 658663 Part 1, No. 2A, February 1999 c 1999 Publi... more Page 1. Jpn. J. Appl. Phys. Vol. 38 (1999) pp. 658663 Part 1, No. 2A, February 1999 c 1999 Publication Board, Japanese Journal of Applied Physics Optical Absorption and Electrical Conductivity of Amorphous Carbon Thin Films from Camphor: A Natural Source Sharif Md. ...
Annals of Geophysics, 2012
ABSTRACT In 2008, a radio receiver that works in very low frequency (VLF; 20-60 kHz) and LF (150-... more ABSTRACT In 2008, a radio receiver that works in very low frequency (VLF; 20-60 kHz) and LF (150-300 kHz) bands was developed by an Italian factory. The receiver can monitor 10 frequencies distributed in these bands, with the measurement for each of them of the electric field intensity. Since 2009, to date, six of these radio receivers have been installed throughout Europe to establish a 'European VLF/LF Network'. At present, two of these are into operation in Italy, and the remaining four are located in Greece, Turkey, Portugal and Romania. For the present study, the LF radio data collected over about two years were analysed. At first, the day-time data and the night-time data were separated for each radio signal. Taking into account that the LF signals are characterized by ground-wave and sky-wave propagation modes, the day-time data are related to the ground wave and the night-time data to the sky wave. In this framework, the effects of solar activity and storm activity were defined in the different trends. Then, the earthquakes with M ≥5.0 that occurred over the same period were selected, as those located in a 300-km radius around each receiver/transmitter and within the 5th Fresnel zone related to each transmitter-receiver path. Where possible, the wavelet analysis was applied on the time series of the radio signal intensity, and some anomalies related to previous earthquakes were revealed. Except for some doubt in one case, success appears to have been obtained in all of the cases related to the 300 km circles in for the ground waves and the sky waves. For the Fresnel cases, success in two cases and one failure were seen in analysing the sky waves. The failure occurred in August/September, and might be related to the disturbed conditions of the ionosphere in summer
Progress In Electromagnetics Research, 2009
Abstract: A system generating 1.8 GHz electromagnetic fields for bio-medical and behavioral study... more Abstract: A system generating 1.8 GHz electromagnetic fields for bio-medical and behavioral study on laboratory animals was designed and implemented. The system is based on a reverberation chamber. An input power up to 5 W can be sent to an indoor transmitting ...
Journal of Instrumentation, 2011
In a previous study, an apparatus generating 1.8 GHz electromagnetic radiation for ``in vivo&... more In a previous study, an apparatus generating 1.8 GHz electromagnetic radiation for ``in vivo'' biomedical study was designed and implemented. The apparatus consisted of a reverberation chamber and it reproduced a habitat similar to the usual one for the laboratory animals. Plexiglas boxes with 300 cc physiological liquid were utilized as simple phantoms. For the measurements a small Electric Field
Materials Science Forum, 1996
Thin Solid Films, 2004
... Structural and optical characterization of undoped and indium-doped CdS films grown by pulsed... more ... Structural and optical characterization of undoped and indium-doped CdS films grown by pulsed laser ... vary the Cd:S ratio [4], or the doping with Silver [5] or Indium [1] atoms. ... to obtain undoped and n-doped CdS films, like chemical bath deposition [6], electrodeposition [7], spray ...
Natural Hazards and Earth System Science, 2008
ABSTRACT On 22 August 2005 an earthquake with magnitude M =4.7 occurred in the Anzio (central Ita... more ABSTRACT On 22 August 2005 an earthquake with magnitude M =4.7 occurred in the Anzio (central Italy) offshore area. From 2002, a VLF-LF radio receiver is into operation in Bari (southern Italy). The intensity and the phase of the signals transmitted by GB ( f =16 kHz, United Kingdom), FR ( f =20.9 kHz, France), GE ( f =23.4 kHz, Germany), IC ( f =37.5 kHz, Island) and IT ( f =54 kHz, Sicily, Italy) has been monitored with a 5 s sampling rate. The previous epicenter is near enough to some of the radio paths and the data collected were studied in order to reveal possible seismic effects. The raw analysis revealed a clear drop in the intensity of the FR radio signal on 19 August. Then the wavelet analysis was applied to the intensity and the phase data of the different radio signals. In the mentioned day an increase in the band 60–120 min was revealed in the spectra of the FR signal. Then the principal component analysis was applied and again the 19 August stood up as an anomalous day for the FR radio signal. The path of this signal, among the paths of the five radio signals collected by the Bari receiver, is the nearest to the mentioned epicentre and the anomaly revealed on 19 August appears as a precursor of the earthquake. This result confirms the possible precursor revealed by other researchers in the air Rn content in a site located 5 miles far from the epicenter.
Journal of Non-Crystalline Solids, 2009
Natural and synthetic melanin have been investigated by means of optical, electrical and photoele... more Natural and synthetic melanin have been investigated by means of optical, electrical and photoelectronic measurements. Optical measurements evidence absorption curves which allow to estimate optical gap for synthetic melanin, by using Tauc's method. Dark conductivity and photoconductivity measurements were performed as a function of temperature and for different duration of thermal treatments. It has been evidenced that both quantities are thermally activated and thermal treatments play a very important role as far as gap states are concerned.
Electrical characteristics of hydrogen-terminated diamond metal-oxide-semiconductor with atomic l... more Electrical characteristics of hydrogen-terminated diamond metal-oxide-semiconductor with atomic layer deposited HfO2 as gate dielectric Appl. Phys. Lett. 102, 112910 (2013) Efficient reduction of defects in non-polar and (1122) semi-polar GaN grown on nanorod templates Appl. Phys. Lett. 102, 101906 (2013) Compensation effects in GaN:Mg probed by Raman spectroscopy and photoluminescence measurements J. Appl. Phys. 113, 103504 (2013) Structural analysis of Au/TiO2 thin films deposited on the glass substrate Appl. Phys. Lett. 102, 091603 (2013) Epitaxial growth of radial Si p-i-n junctions for photovoltaic applications Appl. Phys. Lett. 102, 093113 (2013) Additional information on J. Appl. Phys.
Diamond and Related Materials, 2010
Polycrystalline diamond films with a thickness of about 2µm were deposited by chemical vapour dep... more Polycrystalline diamond films with a thickness of about 2µm were deposited by chemical vapour deposition on silicon substrates in continuous and pulsed wave regimes with duty cycle between 25% and 100%. The thermoluminescent behaviour of these films was analysed in the temperature range 323–723K after β irradiation with doses in the range 7–107Gy. All the films exhibit a dosimetric peak
Journal of Non-Crystalline Solids, 1992
... Non-Crystalline Solids 139 (1992) 60-66 ;OVRNA L Or North-Holland NON-CRYSTALLINE SOLIDS Urba... more ... Non-Crystalline Solids 139 (1992) 60-66 ;OVRNA L Or North-Holland NON-CRYSTALLINE SOLIDS Urbach tail in amorphous gallium arsenide films Roberto Murri, Luigi Schiavulli, NicolaPinto and Teresa ... [5\] R. Murri, F. Gozzo, N. Pinto, L. Schiavulli, C. De Blasi and ...
Solid-State Electronics, 2005
The use of GaN as an alternative interlayer for stable passivation of gallium arsenide surface is... more The use of GaN as an alternative interlayer for stable passivation of gallium arsenide surface is investigated. To this aim remote N 2 -H 2 plasma nitridation of the n-doped gallium arsenide surface has been performed. The exposure time to N 2 -H 2 plasmas has been varied in order to form ultrathin GaN layers with different thickness. Gallium nitride layer thickness and composition analysis have been determined by in situ spectroscopic ellipsometry. The changes of the electronic properties of GaAs surface induced by nitridation process have been studied by means of DC and AC electrical characterizations on Schottky barrier diodes tailored on gallium nitride/gallium arsenide structure. The evidence of achievement of GaAs surface electronic passivation under short time plasma treatment will be provided.
InP films have been deposited on amorphous sapphire substrate by means of the metallorganic chemi... more InP films have been deposited on amorphous sapphire substrate by means of the metallorganic chemical vapour deposition technique with and without PH3/H2 plasma preactivation. Polycrystalline materials, having average grain sizes of about 40 nm, which, however, vary according to the growth parameters, were obtained. The structural and compositional disorder strongly influence the optical and electrical properties. The most structurally disordered films present the largest photoluminescence (PL) efficiency and a blue-shift of the whole PL spectra. Radiative recombinations of carriers confined in crystallites having the smallest sizes are proposed to explain such an anomalous behaviour. The temperature dependence of the bandgap follows the well known phenomenological models except for the hydrogenated samples, in which a blue-shift of the intrinsic luminescence band is observed with increasing temperature. This anomalous effect is related to phonon-assisted transitions between nanoclusters with different sizes. Electrical conductivity measurements show different conductivity mechanisms in two different ranges of temperature. In particular, for temperatures lower than 200 K the conduction mechanism is due to a variable-range hopping process.
Thin Solid Films, 2006
A study of the structural, optical and electrical properties of synthetic and natural melanin by ... more A study of the structural, optical and electrical properties of synthetic and natural melanin by means of X-ray diffraction, absorption and photocurrent techniques is reported. The model of the natural melanin film as a network of nano-aggregates of polymeric units based on the indolic structure is proposed to explain the X-ray diffraction results. The shape of the absorption spectra is
Applied Surface Science, 2004
Journal of Luminescence, 2003
The passivation of GaAs (1 0 0) surface has been performed by using remote N 2 -H 2 (3% in H 2 ) ... more The passivation of GaAs (1 0 0) surface has been performed by using remote N 2 -H 2 (3% in H 2 ) RF plasma nitridation. The samples, consisting of n-doped GaAs wafers, show photoluminescence enhancement when the nitridation time and exposure to the plasma are in a narrow temporal window, so that a very thin (about 10 ( A) GaN layer is deposited on the GaAs surface. Pure N 2 nitridation does not provide an efficient passivation, because it results in GaN layers with As and AsN x segregation at the GaN/GaAs interface. Increase of Au-GaAs Schottky barrier with the insertion of GaN interlayer and improvement of current-voltage characteristic have been observed. r
Thin Solid Films, 2001
Page 1. Jpn. J. Appl. Phys. Vol. 38 (1999) pp. 658663 Part 1, No. 2A, February 1999 c 1999 Publi... more Page 1. Jpn. J. Appl. Phys. Vol. 38 (1999) pp. 658663 Part 1, No. 2A, February 1999 c 1999 Publication Board, Japanese Journal of Applied Physics Optical Absorption and Electrical Conductivity of Amorphous Carbon Thin Films from Camphor: A Natural Source Sharif Md. ...
Annals of Geophysics, 2012
ABSTRACT In 2008, a radio receiver that works in very low frequency (VLF; 20-60 kHz) and LF (150-... more ABSTRACT In 2008, a radio receiver that works in very low frequency (VLF; 20-60 kHz) and LF (150-300 kHz) bands was developed by an Italian factory. The receiver can monitor 10 frequencies distributed in these bands, with the measurement for each of them of the electric field intensity. Since 2009, to date, six of these radio receivers have been installed throughout Europe to establish a 'European VLF/LF Network'. At present, two of these are into operation in Italy, and the remaining four are located in Greece, Turkey, Portugal and Romania. For the present study, the LF radio data collected over about two years were analysed. At first, the day-time data and the night-time data were separated for each radio signal. Taking into account that the LF signals are characterized by ground-wave and sky-wave propagation modes, the day-time data are related to the ground wave and the night-time data to the sky wave. In this framework, the effects of solar activity and storm activity were defined in the different trends. Then, the earthquakes with M ≥5.0 that occurred over the same period were selected, as those located in a 300-km radius around each receiver/transmitter and within the 5th Fresnel zone related to each transmitter-receiver path. Where possible, the wavelet analysis was applied on the time series of the radio signal intensity, and some anomalies related to previous earthquakes were revealed. Except for some doubt in one case, success appears to have been obtained in all of the cases related to the 300 km circles in for the ground waves and the sky waves. For the Fresnel cases, success in two cases and one failure were seen in analysing the sky waves. The failure occurred in August/September, and might be related to the disturbed conditions of the ionosphere in summer
Progress In Electromagnetics Research, 2009
Abstract: A system generating 1.8 GHz electromagnetic fields for bio-medical and behavioral study... more Abstract: A system generating 1.8 GHz electromagnetic fields for bio-medical and behavioral study on laboratory animals was designed and implemented. The system is based on a reverberation chamber. An input power up to 5 W can be sent to an indoor transmitting ...
Journal of Instrumentation, 2011
In a previous study, an apparatus generating 1.8 GHz electromagnetic radiation for ``in vivo&... more In a previous study, an apparatus generating 1.8 GHz electromagnetic radiation for ``in vivo'' biomedical study was designed and implemented. The apparatus consisted of a reverberation chamber and it reproduced a habitat similar to the usual one for the laboratory animals. Plexiglas boxes with 300 cc physiological liquid were utilized as simple phantoms. For the measurements a small Electric Field
Materials Science Forum, 1996
Thin Solid Films, 2004
... Structural and optical characterization of undoped and indium-doped CdS films grown by pulsed... more ... Structural and optical characterization of undoped and indium-doped CdS films grown by pulsed laser ... vary the Cd:S ratio [4], or the doping with Silver [5] or Indium [1] atoms. ... to obtain undoped and n-doped CdS films, like chemical bath deposition [6], electrodeposition [7], spray ...
Natural Hazards and Earth System Science, 2008
ABSTRACT On 22 August 2005 an earthquake with magnitude M =4.7 occurred in the Anzio (central Ita... more ABSTRACT On 22 August 2005 an earthquake with magnitude M =4.7 occurred in the Anzio (central Italy) offshore area. From 2002, a VLF-LF radio receiver is into operation in Bari (southern Italy). The intensity and the phase of the signals transmitted by GB ( f =16 kHz, United Kingdom), FR ( f =20.9 kHz, France), GE ( f =23.4 kHz, Germany), IC ( f =37.5 kHz, Island) and IT ( f =54 kHz, Sicily, Italy) has been monitored with a 5 s sampling rate. The previous epicenter is near enough to some of the radio paths and the data collected were studied in order to reveal possible seismic effects. The raw analysis revealed a clear drop in the intensity of the FR radio signal on 19 August. Then the wavelet analysis was applied to the intensity and the phase data of the different radio signals. In the mentioned day an increase in the band 60–120 min was revealed in the spectra of the FR signal. Then the principal component analysis was applied and again the 19 August stood up as an anomalous day for the FR radio signal. The path of this signal, among the paths of the five radio signals collected by the Bari receiver, is the nearest to the mentioned epicentre and the anomaly revealed on 19 August appears as a precursor of the earthquake. This result confirms the possible precursor revealed by other researchers in the air Rn content in a site located 5 miles far from the epicenter.
Journal of Non-Crystalline Solids, 2009
Natural and synthetic melanin have been investigated by means of optical, electrical and photoele... more Natural and synthetic melanin have been investigated by means of optical, electrical and photoelectronic measurements. Optical measurements evidence absorption curves which allow to estimate optical gap for synthetic melanin, by using Tauc's method. Dark conductivity and photoconductivity measurements were performed as a function of temperature and for different duration of thermal treatments. It has been evidenced that both quantities are thermally activated and thermal treatments play a very important role as far as gap states are concerned.
Electrical characteristics of hydrogen-terminated diamond metal-oxide-semiconductor with atomic l... more Electrical characteristics of hydrogen-terminated diamond metal-oxide-semiconductor with atomic layer deposited HfO2 as gate dielectric Appl. Phys. Lett. 102, 112910 (2013) Efficient reduction of defects in non-polar and (1122) semi-polar GaN grown on nanorod templates Appl. Phys. Lett. 102, 101906 (2013) Compensation effects in GaN:Mg probed by Raman spectroscopy and photoluminescence measurements J. Appl. Phys. 113, 103504 (2013) Structural analysis of Au/TiO2 thin films deposited on the glass substrate Appl. Phys. Lett. 102, 091603 (2013) Epitaxial growth of radial Si p-i-n junctions for photovoltaic applications Appl. Phys. Lett. 102, 093113 (2013) Additional information on J. Appl. Phys.
Diamond and Related Materials, 2010
Polycrystalline diamond films with a thickness of about 2µm were deposited by chemical vapour dep... more Polycrystalline diamond films with a thickness of about 2µm were deposited by chemical vapour deposition on silicon substrates in continuous and pulsed wave regimes with duty cycle between 25% and 100%. The thermoluminescent behaviour of these films was analysed in the temperature range 323–723K after β irradiation with doses in the range 7–107Gy. All the films exhibit a dosimetric peak