Ferroelectric materials possess unique properties such as pyroelectricity and piezoelectricity us... more Ferroelectric materials possess unique properties such as pyroelectricity and piezoelectricity useful for a wide range of technological applications, from non-volatile memories to sensors and actuators. Maintaining the continual rate of miniaturization of such devices presents many challenges, and requires a fundamental understanding of the behaviour of ferroelectrics at nanoscopic scales revealing a fascinating new physics
The synthesis of two new types of nanocomposite matrices, the first based on polyallylamine (PAA)... more The synthesis of two new types of nanocomposite matrices, the first based on polyallylamine (PAA) and aminocarbon nanotubes, the second on polyethyleneimine (PEI) and aminocarbon nanotubes, are reported. The surface acoustic wave (SAW) sensors, coated with the two selected nanocomposites, showed good sensitivities when varying the CO2 concentrations in the range (500-5000) ppm. The sensor sensitivity is larger when using
We report on the fabrication of a novel surface acoustic wave device based on piezoelectric inter... more We report on the fabrication of a novel surface acoustic wave device based on piezoelectric interdigital transducers designed in high quality films of Pb(Zr0.2Ti0.8)O3 grown by RF magnetron sputtering. The approach followed is to replace the conventional metallic interdigital transducers by piezoelectric ones consisting of a series of ferroelectric domains with alternating polarization states. The artificial modification of the ferroelectric
ABSTRACT (110) oriented YBa2Cu3O7-delta thin films have been epitaxially grown on vicinal (110)Sr... more ABSTRACT (110) oriented YBa2Cu3O7-delta thin films have been epitaxially grown on vicinal (110)SrTiO3 substrates by pulsed-laser deposition. Films with different oxygen deficiencies were obtained by annealing under various oxygen ambient. These films have very smooth surface and with their c axis aligned in one direction in the substrate plane. Electronic transport and polarized far-infrared reflectivity measurements reveal the unique features of the c-axis charge dynamics. A c-axis far-infrared reflectivity edge associated with the Josephson plasma in the superconducting state is observed. Our results demonstrate the potential usage of (110) thin films for the investigation of intrinsic interlayer charge dynamics as well as device application of high Tc superconductors.
CAS 2011 Proceedings (2011 International Semiconductor Conference), 2011
Two CO2 sensing mechanisms, based on the Hard Soft Acids Bases (HSAB) and Bronsted-Lowry theories... more Two CO2 sensing mechanisms, based on the Hard Soft Acids Bases (HSAB) and Bronsted-Lowry theories, are discussed and compared. They are evaluated by selecting amino groups-based coating layers, which are deposited on Surface Acoustic Wave (SAW) devices for CO2 detection. Experimentally measured CO2 sensitivities of different coating layers, such as polyallylamine (PAA), polyethyleneimine (PEI), nanocomposite matrix based on PAA-aminocarbon nanotubes and PEI-aminocarbon nanotubes, emeraldine, 4-sulfocalix[4]arene-doped polyaniline, matrix based emeraldine and carbonic anhydrase (PACA) are compared and evaluated according to their corresponding sensing mechanism.
One of the problems with the c-axis in-plane aligned YBa2Cu3O7-delta films on different substrate... more One of the problems with the c-axis in-plane aligned YBa2Cu3O7-delta films on different substrates is the cracking perpendicular to the c-axis, which should be avoided if such films are to be used for device applications. The devices based on the Josephson plasma phenomenon, which is a phase collective oscillation of the Cooper pair through the insulating barriers of the intrinsic Josephson junctions, requires carrier controlled (Tc = 60 K), c-axis in-plane aligned and crack-free YBa2Cu3O7-delta films. Here we propose that overdoping of the YBa2Cu3O7-delta films by substituting Ca at the Y site can help to produce crack free, c-axis in-plane aligned films. This would help to anneal the YBa2Cu3O7-delta films at a lower oxygen partial pressure than the pristine YBa2Cu3O7-delta and thus to obtain the 60 K phase with an elongated c-axis. This is because substantial oxygen incorporation into the films during annealing followed by the compression of the c-axis are the main causes of the crack formation. We designed an experiment to get crack free, 60 K phase YBa2Cu3O7-delta films with the c-axis in the substrate plane and we verified our design by fabricating c-axis in-plane aligned (110) oriented Y0.7Ca0.3Ba2Cu3O7- y films on SrTiO3 (110) substrates.
ABSTRACT In-plane c-axis aligned (1 1 0) YBa2Cu3O7−δ thin films on (1 1 0) SrTiO3 substrates have... more ABSTRACT In-plane c-axis aligned (1 1 0) YBa2Cu3O7−δ thin films on (1 1 0) SrTiO3 substrates have been successfully fabricated by pulsed laser deposition, using the self-template method. The oxygen deficiency of the films is controlled in situ by adjusting the annealing oxygen partial pressure PO2. Electronic transport and c-axis far-infrared reflectivity measurements have been conducted on these thin films. It is revealed that in the normal state the carriers are confined in the CuO planes and that their transport across the c-axis is incoherent. A pseudogap develops in the normal state at temperatures well above Tc and it persists in the superconducting state. Upon decreasing the temperature below the critical transition temperature Tc, coherence is built up for the carrier transport along the c-axis and a reflectivity edge associated with the Josephson plasma is observed.
Abstract. The CO2 sensing performance of several coating layers deposited on piezoelectric device... more Abstract. The CO2 sensing performance of several coating layers deposited on piezoelectric devices (Surface and Bulk Acoustic waveSAW/BAW) are discussed and compared. The layers are amino groupsbased polymers and their selection was based on two principles ...
Abstract. The synthesis of two new types of nanocomposite matrices, the first based on polyallyla... more Abstract. The synthesis of two new types of nanocomposite matrices, the first based on polyallylamine (PAA)and amino-carbon nanotubes (amino-CNTs), the second on polyethyleneimine (PEI) and amino-carbon nanotubes, are reported. The surface acoustic wave (SAW) sensors, ...
Ferroelectric materials possess unique properties such as pyroelectricity and piezoelectricity us... more Ferroelectric materials possess unique properties such as pyroelectricity and piezoelectricity useful for a wide range of technological applications, from non-volatile memories to sensors and actuators. Maintaining the continual rate of miniaturization of such devices presents many challenges, and requires a fundamental understanding of the behaviour of ferroelectrics at nanoscopic scales revealing a fascinating new physics
The synthesis of two new types of nanocomposite matrices, the first based on polyallylamine (PAA)... more The synthesis of two new types of nanocomposite matrices, the first based on polyallylamine (PAA) and aminocarbon nanotubes, the second on polyethyleneimine (PEI) and aminocarbon nanotubes, are reported. The surface acoustic wave (SAW) sensors, coated with the two selected nanocomposites, showed good sensitivities when varying the CO2 concentrations in the range (500-5000) ppm. The sensor sensitivity is larger when using
We report on the fabrication of a novel surface acoustic wave device based on piezoelectric inter... more We report on the fabrication of a novel surface acoustic wave device based on piezoelectric interdigital transducers designed in high quality films of Pb(Zr0.2Ti0.8)O3 grown by RF magnetron sputtering. The approach followed is to replace the conventional metallic interdigital transducers by piezoelectric ones consisting of a series of ferroelectric domains with alternating polarization states. The artificial modification of the ferroelectric
ABSTRACT (110) oriented YBa2Cu3O7-delta thin films have been epitaxially grown on vicinal (110)Sr... more ABSTRACT (110) oriented YBa2Cu3O7-delta thin films have been epitaxially grown on vicinal (110)SrTiO3 substrates by pulsed-laser deposition. Films with different oxygen deficiencies were obtained by annealing under various oxygen ambient. These films have very smooth surface and with their c axis aligned in one direction in the substrate plane. Electronic transport and polarized far-infrared reflectivity measurements reveal the unique features of the c-axis charge dynamics. A c-axis far-infrared reflectivity edge associated with the Josephson plasma in the superconducting state is observed. Our results demonstrate the potential usage of (110) thin films for the investigation of intrinsic interlayer charge dynamics as well as device application of high Tc superconductors.
CAS 2011 Proceedings (2011 International Semiconductor Conference), 2011
Two CO2 sensing mechanisms, based on the Hard Soft Acids Bases (HSAB) and Bronsted-Lowry theories... more Two CO2 sensing mechanisms, based on the Hard Soft Acids Bases (HSAB) and Bronsted-Lowry theories, are discussed and compared. They are evaluated by selecting amino groups-based coating layers, which are deposited on Surface Acoustic Wave (SAW) devices for CO2 detection. Experimentally measured CO2 sensitivities of different coating layers, such as polyallylamine (PAA), polyethyleneimine (PEI), nanocomposite matrix based on PAA-aminocarbon nanotubes and PEI-aminocarbon nanotubes, emeraldine, 4-sulfocalix[4]arene-doped polyaniline, matrix based emeraldine and carbonic anhydrase (PACA) are compared and evaluated according to their corresponding sensing mechanism.
One of the problems with the c-axis in-plane aligned YBa2Cu3O7-delta films on different substrate... more One of the problems with the c-axis in-plane aligned YBa2Cu3O7-delta films on different substrates is the cracking perpendicular to the c-axis, which should be avoided if such films are to be used for device applications. The devices based on the Josephson plasma phenomenon, which is a phase collective oscillation of the Cooper pair through the insulating barriers of the intrinsic Josephson junctions, requires carrier controlled (Tc = 60 K), c-axis in-plane aligned and crack-free YBa2Cu3O7-delta films. Here we propose that overdoping of the YBa2Cu3O7-delta films by substituting Ca at the Y site can help to produce crack free, c-axis in-plane aligned films. This would help to anneal the YBa2Cu3O7-delta films at a lower oxygen partial pressure than the pristine YBa2Cu3O7-delta and thus to obtain the 60 K phase with an elongated c-axis. This is because substantial oxygen incorporation into the films during annealing followed by the compression of the c-axis are the main causes of the crack formation. We designed an experiment to get crack free, 60 K phase YBa2Cu3O7-delta films with the c-axis in the substrate plane and we verified our design by fabricating c-axis in-plane aligned (110) oriented Y0.7Ca0.3Ba2Cu3O7- y films on SrTiO3 (110) substrates.
ABSTRACT In-plane c-axis aligned (1 1 0) YBa2Cu3O7−δ thin films on (1 1 0) SrTiO3 substrates have... more ABSTRACT In-plane c-axis aligned (1 1 0) YBa2Cu3O7−δ thin films on (1 1 0) SrTiO3 substrates have been successfully fabricated by pulsed laser deposition, using the self-template method. The oxygen deficiency of the films is controlled in situ by adjusting the annealing oxygen partial pressure PO2. Electronic transport and c-axis far-infrared reflectivity measurements have been conducted on these thin films. It is revealed that in the normal state the carriers are confined in the CuO planes and that their transport across the c-axis is incoherent. A pseudogap develops in the normal state at temperatures well above Tc and it persists in the superconducting state. Upon decreasing the temperature below the critical transition temperature Tc, coherence is built up for the carrier transport along the c-axis and a reflectivity edge associated with the Josephson plasma is observed.
Abstract. The CO2 sensing performance of several coating layers deposited on piezoelectric device... more Abstract. The CO2 sensing performance of several coating layers deposited on piezoelectric devices (Surface and Bulk Acoustic waveSAW/BAW) are discussed and compared. The layers are amino groupsbased polymers and their selection was based on two principles ...
Abstract. The synthesis of two new types of nanocomposite matrices, the first based on polyallyla... more Abstract. The synthesis of two new types of nanocomposite matrices, the first based on polyallylamine (PAA)and amino-carbon nanotubes (amino-CNTs), the second on polyethyleneimine (PEI) and amino-carbon nanotubes, are reported. The surface acoustic wave (SAW) sensors, ...
Uploads