Camelia Florica | University of Bucharest (original) (raw)

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Papers by Camelia Florica

Research paper thumbnail of Self-connected CuO–ZnO radial core–shell heterojunction nanowire arrays grown on interdigitated electrodes for visible-light photodetectors

Scientific Reports

An original photodetector system based on self-connected CuO–ZnO radial core–shell heterojunction... more An original photodetector system based on self-connected CuO–ZnO radial core–shell heterojunction nanowire arrays grown on metallic interdigitated electrodes, operating as visible-light photodetector was developed by combining simple preparation approaches. Metallic interdigitated electrodes were fabricated on Si/SiO2 substrates using a conventional photolithography process. Subsequently, a Cu layer was electrodeposited on top of the metallic interdigitated electrodes. The CuO nanowire arrays (core) were obtained by thermal oxidation in air of the Cu layer. Afterwards, a ZnO thin film (shell) was deposited by RF magnetron sputtering covering the surface of the CuO nanowires. The morphological, structural, compositional, optical, electrical and photoelectrical properties of the CuO nanowire arrays and CuO–ZnO core–shell nanowire arrays grown on metallic interdigitated electrodes were investigated. The performances of the devices were evaluated by assessing the figures of merit of the...

Research paper thumbnail of Transparent indium zinc oxide thin films used in photovoltaic cells based on polymer blends

Thin Solid Films, 2012

Indium zinc oxide (IZO) thin films were obtained using pulsed laser deposition. The samples were ... more Indium zinc oxide (IZO) thin films were obtained using pulsed laser deposition. The samples were prepared by ablation of targets with In concentrations, In/(In+ Zn), of 80 at.%, at low substrate temperatures under reactive atmosphere. IZO films were used as transparent electrodes in polymer-basedpoly(3-hexylthiophene) and 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C61 1:1 blendphotovoltaic cells. The action spectra measurements revealed that IZO-based photovoltaic structures have performances comparable with those using indium-tin-oxide as transparent electrode.

Research paper thumbnail of Electrical Properties of ZnO Nanowires Prepared By Templateless Electrodeposition

Research paper thumbnail of Electrical properties of single CdTe nanowires

Beilstein Journal of Nanotechnology, 2015

Ion track, nanoporous membranes were employed as templates for the preparation of CdTe nanowires.... more Ion track, nanoporous membranes were employed as templates for the preparation of CdTe nanowires. For this purpose, electrochemical deposition from a bath containing Cd and Te ions was employed. This process leads to high aspect ratio CdTe nanowires, which were harvested and placed on a substrate with lithographically patterned, interdigitated electrodes. Focused ion beaminduced metallization was used to produce individual nanowires with electrical contacts and electrical measurements were performed on these individual nanowires. The influence of a bottom gate was investigated and it was found that surface passivation leads to improved transport properties.

Research paper thumbnail of Morphology-controlled synthesis of ZnO structures by a simple wet chemical method

Research paper thumbnail of Influence of Electrodeposition Conditions On the Properties of Samaria Films

Research paper thumbnail of Field Effect Transistor with Electrodeposited ZnO Nanowire Channel

Electrochimica Acta, 2014

ABSTRACT ZnO nanowires were prepared by electrochemical deposition in polycarbonate ion track tem... more ABSTRACT ZnO nanowires were prepared by electrochemical deposition in polycarbonate ion track templates. After the deposition process the polymer templates were dissolved in dichloromethane and the nanowires were harvested by ultrasonication in isopropyl. A droplet of nanowire suspension was placed on a Si/SiO2 substrate patterned with interdigitated electrodes. By means of electron beam lithography single nanowires were selected and provided with electrical contacts. We found that in order to obtain reliable electrical contacts and typical field effect characteristics the electrode deposition process needs to be adapted to the 3 D shape of the wires and that annealing and passivation treatments are necessary.

Research paper thumbnail of Zinc Oxide/Samaria Nanowires with Intense Photoluminescence

ABSTRACT Zinc Oxide is a very interesting material for its luminescent and electroluminescent pro... more ABSTRACT Zinc Oxide is a very interesting material for its luminescent and electroluminescent properties. Electrodeposition allows one to prepare ZnO with desired morphology, structural and optical characteristics. Zinc Oxide can be doped with impurities in order to tune its electrical, optical or magnetic properties. When depositiong from a bath containing both zinc and samarium ions one deposits a bilayer of nanostructured ZnO/Sm2O3 with extremely interesting properties. The luminescence of the film is at least one order of magnitude higher than for a ZnO film deposited in similar conditions. When using a nanoporous membrane as template one can deposit nanowires containing both zinc oxide and samaria and exhibiting similar unusual high photoluminescence. Such nanowires can be easily used as building blocks for fabricating ultraminiaturised optic and optoelectronic devices.

Research paper thumbnail of Superhydrophobic ZnO networks with high water adhesion

Nanoscale Research Letters, 2014

ZnO structures were deposited using a simple chemical bath deposition technique onto interdigitat... more ZnO structures were deposited using a simple chemical bath deposition technique onto interdigitated electrodes fabricated by a conventional photolithography method on SiO2/Si substrates. The X-ray diffraction studies show that the ZnO samples have a hexagonal wurtzite crystalline structure. The scanning electron microscopy observations prove that the substrates are uniformly covered by ZnO networks formed by monodisperse rods. The ZnO rod average diameter and length were tuned by controlling reactants' concentration and reaction time. Optical spectroscopy measurements demonstrate that all the samples display bandgap values and emission bands typical for ZnO. The electrical measurements reveal percolating networks which are highly sensitive when the samples are exposed to ammonia vapors, a variation in their resistance with the exposure time being evidenced. Other important characteristics are that the ZnO rod networks exhibit superhydrophobicity, with water contact angles exceeding 150° and a high water droplet adhesion. Reproducible, easily scalable, and low-cost chemical bath deposition and photolithography techniques could provide a facile approach to fabricate such ZnO networks and devices based on them for a wide range of applications where multifunctionality, i.e., sensing and superhydrophobicity, properties are required. 81.07.-b; 81.05.Dz; 68.08.Bc.

Research paper thumbnail of Self-connected CuO–ZnO radial core–shell heterojunction nanowire arrays grown on interdigitated electrodes for visible-light photodetectors

Scientific Reports

An original photodetector system based on self-connected CuO–ZnO radial core–shell heterojunction... more An original photodetector system based on self-connected CuO–ZnO radial core–shell heterojunction nanowire arrays grown on metallic interdigitated electrodes, operating as visible-light photodetector was developed by combining simple preparation approaches. Metallic interdigitated electrodes were fabricated on Si/SiO2 substrates using a conventional photolithography process. Subsequently, a Cu layer was electrodeposited on top of the metallic interdigitated electrodes. The CuO nanowire arrays (core) were obtained by thermal oxidation in air of the Cu layer. Afterwards, a ZnO thin film (shell) was deposited by RF magnetron sputtering covering the surface of the CuO nanowires. The morphological, structural, compositional, optical, electrical and photoelectrical properties of the CuO nanowire arrays and CuO–ZnO core–shell nanowire arrays grown on metallic interdigitated electrodes were investigated. The performances of the devices were evaluated by assessing the figures of merit of the...

Research paper thumbnail of Transparent indium zinc oxide thin films used in photovoltaic cells based on polymer blends

Thin Solid Films, 2012

Indium zinc oxide (IZO) thin films were obtained using pulsed laser deposition. The samples were ... more Indium zinc oxide (IZO) thin films were obtained using pulsed laser deposition. The samples were prepared by ablation of targets with In concentrations, In/(In+ Zn), of 80 at.%, at low substrate temperatures under reactive atmosphere. IZO films were used as transparent electrodes in polymer-basedpoly(3-hexylthiophene) and 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C61 1:1 blendphotovoltaic cells. The action spectra measurements revealed that IZO-based photovoltaic structures have performances comparable with those using indium-tin-oxide as transparent electrode.

Research paper thumbnail of Electrical Properties of ZnO Nanowires Prepared By Templateless Electrodeposition

Research paper thumbnail of Electrical properties of single CdTe nanowires

Beilstein Journal of Nanotechnology, 2015

Ion track, nanoporous membranes were employed as templates for the preparation of CdTe nanowires.... more Ion track, nanoporous membranes were employed as templates for the preparation of CdTe nanowires. For this purpose, electrochemical deposition from a bath containing Cd and Te ions was employed. This process leads to high aspect ratio CdTe nanowires, which were harvested and placed on a substrate with lithographically patterned, interdigitated electrodes. Focused ion beaminduced metallization was used to produce individual nanowires with electrical contacts and electrical measurements were performed on these individual nanowires. The influence of a bottom gate was investigated and it was found that surface passivation leads to improved transport properties.

Research paper thumbnail of Morphology-controlled synthesis of ZnO structures by a simple wet chemical method

Research paper thumbnail of Influence of Electrodeposition Conditions On the Properties of Samaria Films

Research paper thumbnail of Field Effect Transistor with Electrodeposited ZnO Nanowire Channel

Electrochimica Acta, 2014

ABSTRACT ZnO nanowires were prepared by electrochemical deposition in polycarbonate ion track tem... more ABSTRACT ZnO nanowires were prepared by electrochemical deposition in polycarbonate ion track templates. After the deposition process the polymer templates were dissolved in dichloromethane and the nanowires were harvested by ultrasonication in isopropyl. A droplet of nanowire suspension was placed on a Si/SiO2 substrate patterned with interdigitated electrodes. By means of electron beam lithography single nanowires were selected and provided with electrical contacts. We found that in order to obtain reliable electrical contacts and typical field effect characteristics the electrode deposition process needs to be adapted to the 3 D shape of the wires and that annealing and passivation treatments are necessary.

Research paper thumbnail of Zinc Oxide/Samaria Nanowires with Intense Photoluminescence

ABSTRACT Zinc Oxide is a very interesting material for its luminescent and electroluminescent pro... more ABSTRACT Zinc Oxide is a very interesting material for its luminescent and electroluminescent properties. Electrodeposition allows one to prepare ZnO with desired morphology, structural and optical characteristics. Zinc Oxide can be doped with impurities in order to tune its electrical, optical or magnetic properties. When depositiong from a bath containing both zinc and samarium ions one deposits a bilayer of nanostructured ZnO/Sm2O3 with extremely interesting properties. The luminescence of the film is at least one order of magnitude higher than for a ZnO film deposited in similar conditions. When using a nanoporous membrane as template one can deposit nanowires containing both zinc oxide and samaria and exhibiting similar unusual high photoluminescence. Such nanowires can be easily used as building blocks for fabricating ultraminiaturised optic and optoelectronic devices.

Research paper thumbnail of Superhydrophobic ZnO networks with high water adhesion

Nanoscale Research Letters, 2014

ZnO structures were deposited using a simple chemical bath deposition technique onto interdigitat... more ZnO structures were deposited using a simple chemical bath deposition technique onto interdigitated electrodes fabricated by a conventional photolithography method on SiO2/Si substrates. The X-ray diffraction studies show that the ZnO samples have a hexagonal wurtzite crystalline structure. The scanning electron microscopy observations prove that the substrates are uniformly covered by ZnO networks formed by monodisperse rods. The ZnO rod average diameter and length were tuned by controlling reactants' concentration and reaction time. Optical spectroscopy measurements demonstrate that all the samples display bandgap values and emission bands typical for ZnO. The electrical measurements reveal percolating networks which are highly sensitive when the samples are exposed to ammonia vapors, a variation in their resistance with the exposure time being evidenced. Other important characteristics are that the ZnO rod networks exhibit superhydrophobicity, with water contact angles exceeding 150° and a high water droplet adhesion. Reproducible, easily scalable, and low-cost chemical bath deposition and photolithography techniques could provide a facile approach to fabricate such ZnO networks and devices based on them for a wide range of applications where multifunctionality, i.e., sensing and superhydrophobicity, properties are required. 81.07.-b; 81.05.Dz; 68.08.Bc.