Polycrystalline lead selenide thin film has now emerged as a promising choice for low-cost and uncooled MWIR detectors and arrays operating at room temperature within the 3~5 µm wavelength range. LCDG (Laser Components Detector Groups) has successfully fabricated a new version of PbSe thin films using the chemical bath deposition (CBD) method on quartz substrates, enabling the development of infrared detectors and arrays with robust and high production yield. To achieve efficient activation of the PbSe thin film, LCDG investigates PbSe material from chemical reaction of the bath deposition to final packaging to meet various customer specifications and establishes PbSe detectors based on nano- and micro-particles embedded PbSe thin film, resulting in exceptional MWIR photoconductive response at room temperature. The characterization of PbSe thin film reveals the presence of various nanostructures, such as nano- and micro-particles as well as Pb-oxide phases and Pb-iodine phase carrier transporting channels. This paper reports the MWIR performance of the uncooled LCDG’s PbSe detector, focusing on responsivity, EQE, 1/f noise and FTIR spectral response (77K-340K), and D*.
The transport properties of W-doped thermochromic V1-xWxO2 (x=0 and 0.0074) thin films prepared by pulsed laser deposition were studied to understand the effect of doping on the electrical properties of these films. Temperature dependent magneto-transport measurements (Hall effect) in magnetic fields up to 9 Tesla were performed on thin film vanadium dioxide (VO2) across the Mott metal-insulator transition (MIT). The Hall carrier density increases by 4 orders of magnitude at MIT. The Hall mobility varies little across the MIT and remains low at ~ 0.05 cm2 /V sec. The majority carriers are electrons. Magneto-resistance is small and positive. Comparison of the three Hall parameters including carrier concentration, conductivity and mobility between various doping levels on both metallic and insulating state are reported and a model has been proposed. A correlation between carrier concentration and conductivity of VO2 films is observed but doesn’t exist between carrier concentration and mobility.
Vanadium dioxide (VO2) is a well-known phase change material that shows a metal to insulator transition at temperatures near 68 °C. It has many potential applications in science and engineering. In this study, VO2 thin film based planar spiral tunable inductors were designed and fabricated on a sapphire substrate. This approach can be a potential solution for reconfigurable RF/microwave wireless communication systems. According to the experimental results, fabricated inductors show a 43.4 % (from 2.19 nH to 1.24 nH) tuning range at 2 GHz when the VO2 thin film layer undergoes the insulator-to-metal transition from room temperature to temperatures above the transition. This result confirms that the proposed inductor structure was fully functional with the successful inductance tuning capability.
Analog phase shifters are investigated with a periodic structure that includes Barium Strontium Titanate ferroelectric thin film varactors in shunt or serial connection to the coplanar waveguide transmission line. The phase shift is achieved by applying a DC bias to the varactors and changing the reactance in the circuit. The goal of this paper is to characterize the shunt capacitive varactors regarding the voltage dependence of the capacitance, loss tangent, and insertion losses at different bias voltages. Quality factor analysis is also conducted taking the parasitic effects into account. Repeated measurements show that the capacitance of a single cell is tuned from 0.8pF to 0.2pF under a DC bias of 0-10V while the loss tangent is kept under 0.01 in the frequency range of 0-40GHz. Insertion loss is tuned from -4dB to less than -0.6dB from 0 to 10V with a Figure of Merit of 14 degrees/dB at 10GHz and the total quality factor of the unit cell is around 6.7 to 10 at 10GHz with matched port impedance. By cascading 10-25 single unit cells, the phase shift is expected to reach 360 degrees with minimum insertion loss.
A resonant circuit combining a 3D inductor with the barium strontium titanate thin film varactor, is presented in this work. The filter was fabricated using a 3D inductor fabrication process. The modeling of the filter was examined using the Advanced Design System (ADS). The measurement results showed that the resonant frequencies were around 10 GHz and correlated to different number of turns of 3D inductor. The inductances extracted from the equivalent circuit varied from 0.28 nH to 0.37 nH.
In this study, we demonstrated the use of DNA-CTMA (DC) in combination with PolyVinylidene Fluoride (PVDF)
as a host matrix or separator for Lithium based electrolyte to form solid polymer/gel like electrolyte for potential
application in Li-ion batteries. The addition of DC provided a better thermal stability of the composite electrolyte as
shown by the thermos-gravimetric analysis (TGA). The AC conductivity measurements suggest that the addition of
DC to the gel electrolyte had no effect on the overall ionic conductivity of the composite. The obtained films are
flexible with high mechanical stretch-ability as compared to the gel type electrolytes only.
Due to their excellent electrical, optical, and mechanical properties, nanosized single wall carbon nanotubes (SWNTs)
have attracted significant attention as a transducing element in nano-bio sensor research. Controlled assembly, device
fabrication, and bio-functionalization of the SWNTs are crucial in creating the sensors. In this study, working biosensor
platforms were created using dielectrophoretic assembly of single wall carbon nanotubes (SWNTs) as a bridge between
two gold electrodes. SWNTs in a commercial SDS surfactant solution were dispensed in the gap between the two gold
electrodes, followed by applying an ac voltage across the two electrodes. The dielectrophoresis aligns the CNTs and
forms a bridge between the two electrodes. A copious washing and a subsequent annealing of the devices at 200 ᵒC
remove the surfactants and create an excellent semiconducting (p-type) bridge between the two electrodes. A liquid
gated field effect transistor (LGFET) was built using DI water as the gate dielectric and the SWNT bridge as the channel.
Negative gate voltages of the FET increased the drain current and applying a positive gate voltage of +0.5V depleted the
channel of charges and turned the device off. The biosensor was verified using both the two terminal and three terminal
devices. Genomic salmon DNA dissolved in DI water was applied on the SWNT bridge in both type of devices. In the
two terminal device, the conductance of the bridge dropped by 65x after the binding of the DNA. In the LGFET, the
transconductance of the device decreased 2X after the binding of the DNA. The binding of the DNA also suppressed
hysteresis in the Drain Current vs Gate Voltage characteristics of the LGFET.
Many papers have been published on the properties of deoxyribonucleic acid (DNA) and DNAhexadecyltrimethylammonium
chloride (CTMA) and their applications in electronics and photonics. This paper is a
review of some of the properties and their related applications for other types of naturally occurring materials,
nucleic acid bases or nucleobases which make up the DNA molecules. Nucleobases under investigation included
guanine, cytosine, adenine and thymine. Potential applications include electron blocking layers for organic light
emitting diodes, gate dielectrics for organic thin film transistors and protective layers for polymer-based capacitors.
The potential of bio-dielectrics for space applications was explored using deoxyribonucleic acid (DNA)-based biopolymers.
Un-doped DNA, as well as titanium dioxide (TiO2) nanoparticle (rutile form)-doped DNA were processed
and evaluated. Characterized parameters were temperature stability, resistivity, dielectric constant, dielectric loss and
radiation tolerance. The dielectric constant and dielectric loss of un-doped DNA and TiO2-doped DNA were measured
for both pre- and post- exposure to approximately100 krad Gamma-ray radiation. There was little change in the
dielectric constant and dielectric loss of the un-doped DNA sample with exposure to radiation. However, there was a
significant reduction in the dielectric constant of the TiO2-doped DNA sample.
DNA-CTMA is an attractive material to explore for reconfigurable optical and electronic devices. Its dielectric
constant at microwave frequencies can be tuned by applying a DC electric field. In this work, the origin of dielectric
tunability and other ferroelectric-like behavior observed in DNA-CTMA films is investigated. Results suggest that
the dominant polarization mechanism is ionic in nature and is caused by intentionally retaining excess ions in the
DNA-CTMA precipitate during processing.
This paper presents a memristor based unit cell design for a readout integrated circuit (ROIC). The memristor is a nonvolatile
nanoscale circuit component that has dynamic resistance dependent on the total charge applied between the
positive and negative terminals. In the circuit presented, the memristor acts as the integrator in the unit cell. This
eliminates the need for a large integrating capacitor. Simulations demonstrate the functionality of the unit cell, where the
memristor is accurately modeled according to previously published device characterization data. The results show that
memristors can potentially be used to reduce the unit cell area, which could increase the fill factor of the photodetector in
single chip detector and readout designs.
The memristor, experimentally verified for the first time in 2008, is one of four fundamental passive circuit elements (the
others being resistors, capacitors, and inductors). Development and characterization of memristor devices and the design
of novel computing architectures based on these devices can potentially provide significant advances in intelligence
processing systems for a variety of applications including image processing, robotics, and machine learning. In
particular, adaptive coded aperture (diffraction) sensing, an emerging technology enabling real-time, wide-area
IR/visible sensing and imaging, could benefit from new high performance biologically inspired image processing
architectures based on memristors. In this paper, we present results from the fabrication and characterization of
memristor devices utilizing titanium oxide dielectric layers in a parallel plate conuration. Two versions of memristor
devices have been fabricated at the University of Dayton and the Air Force Research Laboratory utilizing varying
thicknesses of the TiO2 dielectric layers. Our results show that the devices do exhibit the characteristic hysteresis loop in
their I-V plots.
Adaptive coded aperture (diffraction) sensing, an emerging technology enabling real-time, wide-area IR/visible sensing
and imaging, could benefit from new high performance biologically inspired image processing architectures. The
memristor, a novel two terminal passive device can enable significantly powerful biologically inspired processing
architectures. This device was first theorized by Dr. Leon Chua in 1971. In 2008, HP Labs successfully fabricated the
first memristor devices. Due to its unique properties, the memristor can be used to implement neuromorphic functions as
its dynamics closely model those of a synapse, and can thus be utilized in biologically inspired processing architectures.
This paper uses existing device models to determine how device parameters can be tuned for the memristor to be used in
neuromorphic circuit design. Specifically, the relation between the different models and the number of states the device
can hold are examined.
In this paper we present our current research in developing non-conductive, optically transparent electromagnetic
interference (EMI) or radio frequency (RF) shielding. It uses metallic nanopowders blended with deoxyribonucleic acid
(DNA) based host materials. Recent results of this DNA-based EMI shielding demonstrate 18-27dB over a frequency
range of 18 - 6 GHz, respectively, with an electrical resistivity measuring > 20MΩ for a 20 μm dielectric spacing. These
films were optical transparent in the visible wavelength range.
Deoxyribonucleic acid (DNA)-based biopolymers posses unique electronic and self assembly properties that render them suitable organic semiconductors for organic field effect transistors. Doping DNA molecules with conductive guests has resulted in a significant decrease of the overall resistivity of the blend with effective free charge carrier mobilities comparable to other conductive polymers such as pentacene and poly(3-hexylthiophene) (P3HT). In this paper we discuss doping DNA with single wall carbon nanotubes (SWCNTs) and transistor behavior.
This paper demonstrates the use of DNA based biopolymers as semiconducting thin films in organic field effect
transistors. The "doping" of the DNA molecules with conductive polymers leads to a significant decrease of the
overall resistivity in the blend with effective free charge carrier mobilities comparable to other conductive polymers
such as Pentacene and P3HT. Baytron P as well as single wall carbon nanotubes (SWCNT) have been explored as "doping" conductive polymers.
This paper reports on the use of new DNA-based biopolymers as the semiconducting layer in field effect transistors. Thin-film field effect transistor (FET) structures are fabricated with two different DNA-biopolymers as semiconductor layers, and two different field effect transistor structures are studied. Current voltage characteristics of the FETs show that the devices are operating in depletion mode.
A new capacitive test structure is used to characterize biopolymers at microwave frequencies. The new test
structure is comprised of a parallel plate capacitor, combined with coplanar waveguide-based input and output feed
lines. This allows electrical measurements to be taken easily under an applied DC electric field and at various
temperatures. The dielectric properties are characterized for two biopolymer thin films: a deoxyribonucleic acid
(DNA)-based film and a bovine serum albumin (BSA)-based film. These bio-dielectric thin films are compared
with a standard commercial polymer thin film, poly[Bisphenol A carbonate-co-4,4'(3,3,5-trimethyl
cyclohexylidene) diphenol], also known as amorphous polycarbonate (APC).
A new capacitive test structure is used to characterize biopolymers at microwave frequencies. The new test structure is comprised of a parallel plate capacitor, combined with coplanar waveguide-based input and output feed lines. This allows microwave measurements to be taken easily under an applied DC electric field. The microwave dielectric properties are characterized for two biopolymer thin films: a deoxyribonucleic acid (DNA)-based film and a bovine serum albumin (BSA)-based film. These bio-dielectric thin-films are compared with a standard commercial polymer thin film, poly[Bisphenol A carbonate-co-4,4'(3,3,5-trimethyl cyclohexylidene) diphenol], or amorphous polycarbonate (APC).
Polymers have a number of attributes that make them highly desirable for use in the design and fabrication of optical
waveguide devices, such as modulators and directional couplers. They have relatively low (1.5-1.7) refractive indices,
low (~4) dielectric constants at gigahertz frequencies, stable at high (150-190oC) temperatures, resistivities that can be
tailored by adding guest molecules and electro-optical responses via the addition of chromophore molecules. These
materials are easily spin-coated on glass, quartz or silicon wafers to form optically conducting films that have low (1-2
dB/cm) optical loss at the near-IR communication wavelengths. In this paper we update resistivity, dielectric, electrooptic
coefficient and waveguide loss characterization methods and improvements that we are using to provide the data
needed to fabricate polymer waveguide devices and report new results for DNA-based polymers.
Suitable organic and polymeric based materials for electronic and photonic applications must possess the desired
electromagnetic and optical properties to achieve optimal device performance in order to be more competitive with their
inorganic counterparts. A new class of biopolymer, processed from purified marine-based deoxyribonucleic acid
(DNA), has been investigated for use in both electronic and photonic applications and has demonstrated promise as an
excellent dielectric and optical waveguide material. In this paper we present examples of devices using this new DNA-based
biopolymer.
Suitable polymer-based photonic materials must possess the desired optical and electromagnetic properties for optimal device performance depending on the intended application. A new class of polymer, processed from purified deoxyribonucleic acid (DNA), has been investigated for use in photonic applications and has shown promise as an excellent optical waveguide material. In this paper we present the current optical and electronic properties of this new DNA-based biopolymer, including optical loss, temperature stability, refractive index, resistivity, dielectric constant and microwave insertion loss.
Optical materials for waveguiding applications must possess the desired optical and electromagnetic properties for optimal device performance. Purified deoxyribonucleic acid (DNA), derived from salmon sperm, has been investigated for use as an optical waveguide material. In this paper we present the materials processing and optical and electromagnetic characterization of this purified DNA to render a high quality, low loss optical waveguide material.
When one thinks of suitability in space environments, irradiation tolerance typically is the first property that comes to mind. In addition to irradiation tolerance, however, suitable photonic materials must also possess the desired optical and electromagnetic properties for optimal device performance. Extracted and purified deoxyribonucleic acid (DNA), derived from salmon, has been investigated for use in photonic applications and has shown promise as an excellent optical waveguide material. In this paper we present the properties of DNA that are applicable for both ground and space based photonic applications. Such properties include optical loss, temperature stability, refractive index, resistivity, dielectric constant, microwave insertion loss and gamma ray irradiation tolerance.
High critical transition temperature (high Tc) superconducting thin films of
Tl-Ca-Ba-Cu-O (TlCaBaCuO) were fabricated on LaAlO3 substrates in an rf magnetron
sputtering system. As-deposited thin films were sintered and annealed in a
thallium rich ambient to obtain superconductivity with a zero resistance critical
temperature (Tc) at 103 K. X-ray diffraction (XRD) results showed that the thin
films were highly c-axis oriented with both Tl2Ca2Ba2Cu3O (2223) and
Tl2CalBa2Cu2Ox (2122) phases present. A wet chemical etching process was used
for patterning the as-deposited TlCaBaCuO thin films. Linewidths as small as 25
m were patterned using standard photolithography and wet chemical etching
techniques. A ring resonator designed for a center frequency of 30 GHz has been
fabricated.
High temperature superconducting Tl-Ca-Ba-Cu-0 thin films were sputter deposited from a single composite powder target on SrTiO3 and LaAlO3 substrates, in an rf magnetron sputtering system. The as-deposited thin films were sintered and annealed in an excess Tl partial pressure to obtain superconductivity. The superconducting films were characterized by scanning electron microscope (SEM), x-ray diffraction (XRD) and resistance vs temperature (R vs T) measurements. Fine line features as small as 25 jim were obtained in as-deposited thin films using standard photolithography and wet chemical etching in a weak acid. From the XRD and SEM results, the annealed thin films were found to be highly c-axis oriented, with smooth platelets of 2-10 pm in size. The R vs T measurements showed zero resistance at temepratures as high as 107 K on SrTiO3 and 103 K on LaA1O3.
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