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ABSTRACT A miniaturized capacitively coupled contactless conductivity detection (C4D) sensor based on high-k perovskite oxide of barium strontium titanate (BST) has been implemented for the first time. The BST films (∼120 nm thick) of... more
ABSTRACT A miniaturized capacitively coupled contactless conductivity detection (C4D) sensor based on high-k perovskite oxide of barium strontium titanate (BST) has been implemented for the first time. The BST films (∼120 nm thick) of Ba0.25Sr0.75TiO3 composition were prepared on a p-Si-SiO2-Pt structure by pulsed laser deposition technique using BST targets fabricated by the self-propagating high-temperature synthesis method. The Pt electrodes were buried into the SiO2 layer to obtain a planar structure. For comparison, contact-mode electrolyte-conductivity (EC) sensors without the protective BST layer were also fabricated. To study the influence of the protective BST layer, both sensors were characterized in electrolyte solutions with various conductivities using two- and four-electrode operation modes. The impedance spectra were recorded in a frequency range from 1 Hz to 1 MHz. An equivalent circuit of the C4D sensor is discussed as well. Both, the EC and C4D sensor, demonstrate nearly identical sensor characteristics. The obtained results clearly show the benefits of the use of the BST-based C4D sensor in a four-electrode configuration for contactless conductivity measurements. A linear dependence between the measured conductance and the electrolyte conductivity is obtained in a wide range of electrolyte conductivity from 0.3 mS/cm to 50 mS/cm. Moreover, typical problems associated with contact-mode EC detection such as the effect of possible redox processes, contamination and fouling of electrodes during continuous measurements can be minimized, thus, enhancing the life-time of conductivity sensors considerably.
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The on-chip integration of multiple biochemical sensors based on field-effect electrolyte-insulator-semiconductor capacitors (EISCAP) is challenging due to technological difficulties in realization of electrically isolated EISCAPs on the... more
The on-chip integration of multiple biochemical sensors based on field-effect electrolyte-insulator-semiconductor capacitors (EISCAP) is challenging due to technological difficulties in realization of electrically isolated EISCAPs on the same Si chip. In this work, we present a new simple design for an array of on-chip integrated, individually electrically addressable EISCAPs with an additional control gate (CG-EISCAP). The existence of the CG enables an addressable activation or deactivation of on-chip integrated individual CG-EISCAPs by simple electrical switching the CG of each sensor in various setups, and makes the new design capable for multianalyte detection without cross-talk effects between the sensors in the array. The new designed CG-EISCAP chip was modelled in so-called floating/short-circuited and floating/capacitively-coupled setups, and the corresponding electrical equivalent circuits were developed. In addition, the capacitance-voltage curves of the CG-EISCAP chip in...
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Research Interests: Thin Film and Inductance
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Materials Science Forum Vols. 457-460 (2004) pp 977-980 Online available since 2004/Jun/15 at www.scientific.net © (2004) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/MSF.457-460.977 ... All rights reserved. No part... more
Materials Science Forum Vols. 457-460 (2004) pp 977-980 Online available since 2004/Jun/15 at www.scientific.net © (2004) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/MSF.457-460.977 ... All rights reserved. No part of ...
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ABSTRACT It is well known [1-2] that values of the negative dynamic resistance (NDR) can be increased in transit-time structures if the phase lag of component of the current, which is in anti phase with the local electric field, is... more
ABSTRACT It is well known [1-2] that values of the negative dynamic resistance (NDR) can be increased in transit-time structures if the phase lag of component of the current, which is in anti phase with the local electric field, is increased. In some cases it can be achieved by the use of a low-mobility material in order to reduce velocities of space charge carriers in the source region. The other way to increase the phase lag is the use of hetero-junction double velocity and quantum-well structures [3-5]. The aim of the present paper is to show how to use different hetero-structures (for example, Si/SiC, 3C-SiC/6H-SiC, 3C-SiC/4H-SiC) for the fabrication of double velocity SiC-based IMPATT diodes.
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ABSTRACT Metal-semiconductor tunneling contact characteristics on the base of Silicon Carbide with trap levels in the semiconductor bandgap are theoretically examined. It is shown that the magnitude of avalanche voltage can be increased... more
ABSTRACT Metal-semiconductor tunneling contact characteristics on the base of Silicon Carbide with trap levels in the semiconductor bandgap are theoretically examined. It is shown that the magnitude of avalanche voltage can be increased under the influence of trapping charge carriers tunneling from the metal to the semiconductor. It is shown that with the increased of temperature the breakdown avalanche voltage of the contacts is decreased.
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ABSTRACT Noise characteristics of silicon carbide Schottky barrier field effect transistors (MESFET) are examined for the case of the operation in small-signal regime and the presence of deep impurity levels and electron traps in the band... more
ABSTRACT Noise characteristics of silicon carbide Schottky barrier field effect transistors (MESFET) are examined for the case of the operation in small-signal regime and the presence of deep impurity levels and electron traps in the band gap of the channel. A new model of calculations of noise is suggested. It is shown that the noise measure of the short channel MESFET can be decreased within certain high frequency range.
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(Ba,Sr)TiO3 field effect capacitive EIS sensors based on a Si/SiO2 structure are presented. In this study, the first proposed (Ba,Sr)TiO3 ceramic targets are prepared by SHS (self-propagating high-temperature synthesis) method, and... more
(Ba,Sr)TiO3 field effect capacitive EIS sensors based on a Si/SiO2 structure are presented. In this study, the first proposed (Ba,Sr)TiO3 ceramic targets are prepared by SHS (self-propagating high-temperature synthesis) method, and (Ba,Sr)TiO3 membranes for the EIS structure as a pH-sensitive layer is fabricated by PLD (pulsed laser deposition) method. These EIS structures are studied from 3 to 11 pH solutions. The pH response is the quasi-Nernstian response of 38-58mV/pH via the C-V measurements of an EIS structure. The results show the possibility to use (Ba,Sr)TiO3 perovskite oxides as a sensing material for potentiometric pH sensors.
A new construction of a miniaturised contactless electrolyte conductivity sensor based on Pt interdigitated electrodes is proposed. High dielectric permittivity perovskite-oxide films of different composition have been used as a covering... more
A new construction of a miniaturised contactless electrolyte conductivity sensor based on Pt interdigitated electrodes is proposed. High dielectric permittivity perovskite-oxide films of different composition have been used as a covering insulator material on metallic electrodes for the first time. An equivalent circuit of the sensor is developed and the impedance characteristics are theoretically calculated and experimentally investigated. The operation frequency range is evaluated analytically.
An-amorphous BaxSr1-x TiO3/ polycrystalline (pc) silicon anis-type heterojunction capacitance was evaluated theoretically and studied experimentally, taking into account the presence of oxygen vacancies in ferroelectric film as well as... more
An-amorphous BaxSr1-x TiO3/ polycrystalline (pc) silicon anis-type heterojunction capacitance was evaluated theoretically and studied experimentally, taking into account the presence of oxygen vacancies in ferroelectric film as well as non-linear dependence of the ferroelectric films dielectric permittivity on the electric field for different values of oxygen vacancies concentration and doping levels in silicon.
ABSTRACT Processes in a HTSC thin film circuit with nonlinear parametric active resistance and inductance are theoretically examined. A possibility to control values of the equivalent parameters of circuit by optical radiation modulated... more
ABSTRACT Processes in a HTSC thin film circuit with nonlinear parametric active resistance and inductance are theoretically examined. A possibility to control values of the equivalent parameters of circuit by optical radiation modulated on the intensity was shown.
ABSTRACT A generalized two-liquid model is used to analyze theoretically the parametric amplifier effects in high-Tc superconducting thin films at the irradiation of the latter by an optical radiation modulated by the intensity. The... more
ABSTRACT A generalized two-liquid model is used to analyze theoretically the parametric amplifier effects in high-Tc superconducting thin films at the irradiation of the latter by an optical radiation modulated by the intensity. The expressions of the components of surface impedance parameters-dependencies are obtained, the condition of parametric "pump" is simulated, and the gain in power is calculated. The possibility of the creation of the parametric regeneration on the modulation frequency of the surface impedance of a HTSC films is offered.
ABSTRACT Nanoscale (30–100 nm) films of BiFeO3/BaTiO3/Ni0.5Zn0.5Fe2O4 complex composition have been obtained by the pulsed-laser deposition method. Optical properties of the films were studied in the wavelength range of 250–1000 nm. It is... more
ABSTRACT Nanoscale (30–100 nm) films of BiFeO3/BaTiO3/Ni0.5Zn0.5Fe2O4 complex composition have been obtained by the pulsed-laser deposition method. Optical properties of the films were studied in the wavelength range of 250–1000 nm. It is shown that the optical properties of amorphous films deposited at room temperature are explained by the Tauc model for amorphous semiconductors. An increase in the optical gap from 1.7 to 1.95 eV was observed with decreasing film thickness. Allowed direct-band transitions (E g = 3.1 eV) were observed after annealing of films independent of their thickness.
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