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The authors have developed a highly sensitive, compact image sensor comprising a field emitter array (FEA) and a high-gain avalanche rushing amorphous photoconductor (HARP) target with the ultimate aim of developing an ultrahigh sensitivity, compact, high-definition television camera. Double-gated field emitters have the advantage of a compact electron beam focusing system; however, image intensities reproduced by a sensor with the double-gated, Spindt-type field emitter array with the focusing electrode stacked 1.5 μm above the gate electrode were nonuniform owing to low electron beam current. The minimum required electron beam current extracted from the double-gated field emitter array is considered for possible use with the sensor. Furthermore, a suitable field emitter array pitch to balance the electron beam current and the electrostatic-focusing lens strength was simulated. For the sensor's design guidelines, a field emitter array pitch of approximately 3 μm would be reasonable in the case of employing the volcano-structured, doublegated, Spindt-type field emitter array with the focusing electrode placed 0.2 μm below the gate electrode hole. Based on simulation results, an image sensor with the volcano-structured, Spindt-type, 3.1-μm-pitch FEA with the focusing electrode placed 0.2 μm below the gate electrode hole was fabricated. It was confirmed that the minimum electron beam current extracted from the volcano-structured FEA was approximately 2 lA/pix, and the sensor could obtain images with improved image intensity uniformity by utilizing the electrostatic-focusing effect. These results indicate that the volcano-structured, double-gated, Spindt-type FEA is potentially suitable for high-definition television FEA-HARP image sensors. [ABSTRACT FROM AUTHOR]

We investigated the effect of a 3-nm-thick amorphous Si (a-Si) capping layer on the hole transport properties of BaSi2 films. The contact resistance decreased with decreasing resistivity of p-BaSi2 and reached a minimum of 0.35 Qcm². The effect of the a-Si layer was confirmed by higher photores-ponsivities for n-BaSi2 films capped with the a-Si layer than for those without the a-Si layer, showing that the minority carriers (holes) were extracted efficiently across the a-Si/n-BaSi2 interface. Under AM1.5 illumination, the conversion efficiency reached 9.9% in a-Si(3 nm)/p-BaSi2 (20nm)/n-Si solar cells, the highest value ever reported for semiconducting silicides. [ABSTRACT FROM AUTHOR]

ABSTRACT In this study, we report the synthesis, characterization, and photo-responsive properties of a new Y-shaped amphiphilic azo triblock copolymer composed of two isotropic polyethylene glycol (PEG) blocks and an azobenzene liquid crystalline block. The azo block, with two ending groups suitable for the azo coupling reaction, is polymerized by atom transfer radical polymerization with a synthesized initiator containing two functional terminal groups. The macromolecular diazonium salts are prepared by the diazotization of PEG terminated with an amino group. The triblock copolymer is obtained by the azo coupling reaction between the azo block and macromolecular diazonium salts in DMF under mild condition. The intermediates and the obtained triblock copolymer are characterized by 1H NMR, FT-IR, GPC, POM, DSC, TEM, and UV-vis. The photoinduced isomerization behavior of the azo copolymer is investigated by UV-vis. With the addition of water into the solution of the triblock copolymer, spherical aggregates with an average diameter of about 400 nm can be easily obtained. The aggregates are elongated when irradiated with polarized 365 nm UV light. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43695. [ABSTRACT FROM AUTHOR]

The frequency response of ion implanted silicon photoconductive devices designed for coherent detection in time domain terahertz spectroscopy has been studied between 0.2 and 30 THz. Unlike devices using polar photoconductors or ones having polar substrates, which have a complicated response spectrum in the region of their reststrahlen bands, the response of silicon detectors fabricated on silicon substrates is relatively featureless. When used with amplified laser systems, the dynamic range of Si detectors is shown to be very similar to that of GaAs devices with the same geometry over a 20 THz range, superior to air-biased coherent detection (ABCD) at frequencies below ~7 THz and comparable with both ABCD and electro-optic sampling in thin ZnTe crystals between 7 and 20 THz. Together with their ease of use and linear response in terahertz fields approaching 1 MV/cm, this suggests that Si photoconductors could be a competitive choice for sensitive detection in nonlinear hyper-terahertz spectroscopy. [ABSTRACT FROM AUTHOR]

The effect on the J-V behavior of polymer solar cells (PSCs) based on the active layer PTB7:PCBM under a previous application of an external electric field (E) is presented. The active layer is doped with 0.01-0.04 wt. ratio (with respect to PTB7) of poly(9-vinylcarbazole) (PVK) as a photoconductor, and/or 0.25-0.5 wt. ratio of 9-ethylcarbazole (ECZ) as plasticizer. The general PSC structure was Glass-ITO/PEDOT:PSS/PTB7:PCBM: dopant/PFN/FM where dopant means PVK, ECZ or a mixture of them. Field's metal (FM) is an eutectic alloy with a melting point above 62 °C, which is deposited in a vacuum free atmosphere. Electric fields of 5 or −70 V/μm (forward and reversed polarity, respectively) are applied. For PSCs doped with PVK, under forward polarity, it is observed a remarkable variation (36 %) on J: from 7.7 to 4.9 mA/cm, while V remains almost constant: ~0.76 V; whereas with the reversed polarity, a drastic variation of 95 % is observed on V: from 0.76 to 0.04 V; while J value changes from 7.4 to 5.6 mA/cm (24 %). On the other hand, PSCs doped with the combination of ECZ and PVK, an increase of 10 % in J is reached for reversed bias (E = −70 V); and without applying any field, and keep them under N atmosphere, a slower photovoltaic degradation, with respect to that one from all the other studied samples, is shown over 57 days of monitoring them: FF variation is of just 6 % and PCE decays only 21 %. [ABSTRACT FROM AUTHOR]

We explore the effects of surfactant-mediated epitaxy on the structural, electrical, and optical properties of fast metal-semiconductor superlattice photoconductors. Specifically, application of a bismuth flux during growth was found to significantly improve the properties of superlattices of LuAs nanoparticles embedded in In0.53Ga0.47As. These improvements are attributed to the enhanced structural quality of the overgrown InGaAs over the LuAs nanoparticles. The use of bismuth enabled a 30% increase in the number of monolayers of LuAs that could be deposited before the InGaAs overgrowth degraded. Dark resistivity increased by up to ~15× while carrier mobility remained over 2300 cm2/V-s and carrier lifetimes were reduced by >2× at comparable levels of LuAs deposition. These findings demonstrate that surfactant-mediated epitaxy is a promising approach to enhance the properties of ultrafast photoconductors for terahert generation. [ABSTRACT FROM AUTHOR]

The nonlinear dynamics of an optoelectronic negative feedback switching circuit is studied. The circuit, composed of a bulb, a photoresistor, a thyristor and a linear resistor, corresponds to a nightlight device whose light is looped back into its light sensor. Periodic bifurcations and deterministic chaos are obtained by the feedback loop created when the thyristor switches on the bulb in the absence of light being detected by the photoresistor and the bulb light is then looped back into the nightlight to switch it off. The experimental signal is analyzed using tools of delay-embedding reconstruction that yield a reconstructed attractor with fractional dimension and positive Lyapunov exponent suggesting chaotic behavior for some parameter values. We construct a simple circuit model reproducing experimental results that qualitatively matches the different dynamical regimes of the experimental apparatus. In particular, we observe an order-chaos-order transition as the strength of the feedback is varied corresponding to varying the distance between the nightlight bulb and its photo-detector. A two-dimensional parameter diagram of the model reveals that the order-chaos-order transition is generic for this system. [ABSTRACT FROM AUTHOR]

We have developed a highly sensitive, compact image sensor that comprises a field emitter array (FEA) and a high-gain avalanche-rushing amorphous photoconductor target, with the ultimate aim of developing an ultrahighly sensitive, compact, high-definition television camera. Double-gated FEs have an advantage of having a compact electron beam focusing system; however, image intensities reproduced by the sensor were nonuniform due to low electron beam current. Furthermore, the simulated electron beam current disagreed with the measured current. The electron beam current characteristics of two types of double-gated, Spindt-type FEs (both with improved electron beam current extraction) are discussed for possible use within the sensor: convex-structured and volcano-structured. A highly accurate simulation model of the image sensor using a double-gated, Spindt-type FE has been examined; the simulated electron beam currents extracted from the double-gated, Spindt-type FE are in agreement with the measured electron beam currents when the initial electron velocity is assumed, thus suggesting that the simulated anode current–anode voltage characteristic conforms to the measured one. For example, the electron beam currents extracted from the convex-structured and volcano-structured FEs when the focusing electrode is placed 0.2 \mu \textm below the gate electrode opening at a focusing electrode voltage of 15 V are, respectively, 1.8 and 1.9 times larger than that extracted from the previously used FEs when the focusing electrode is stacked 1.5 \mu \textm above the gate electrode. The results show potential for reducing the degradation of the uniformity of the reproduced image’s intensity, and show that the highly accurate simulation model of the sensor is valid to design the double-gated FEAs for the sensor. [ABSTRACT FROM AUTHOR]

Two-color un-cooled narrow-gap MCT (mercury-cadmium-telluride) semiconductor thin layers, grown by liquid phase epitaxy or molecular beam epitaxy methods on high resistivity CdZnTe or GaAs substrates, with bow-type antennas were considered both as sub-terahertz direct detection bolometers and 3 . . . 10-micrometer infrared photoconductors. Optical system with aspheric THz lenses were designed and manufactured. An antenna pattern of structures on the thick substrate was discussed, and sensitivity of detector in both IR and sub-THz regions was measured. [ABSTRACT FROM AUTHOR]

Organic photodetectors (OPDs) based on one-dimensional (1D) micro/nano structures of small molecules as photoactive layers, compared to their inorganic counterparts, have demonstrated attractive advantages of light-weight, low-cost, easy solution processing, large-area detection, and mechanical flexibility. In this chapter, we attempt to present a systematic summary of the significant advances in organic photodetectors based on small-molecule semiconductor materials, in particular for their 1D architectures in the field of photoconductors and phototransistors over the past few years. Firstly, we will give a brief introduction with the purpose of offering an intuitive understanding of OPDs including typical structure geometry, working mechanism and basic performance parameters. Secondly, we will focus our discussion on the specific research progress of OPDs including the development of 1D organic material systems or hybrid materials for different spectral regions and the improvement of device performance. Finally, the general challenges and the potential future directions of this exciting research and technology area are presented. [ABSTRACT FROM AUTHOR]

SU-8, an epoxy-based negative photoresist polymer, is highly suitable for making micro-electro-mechanical systems (MEMS) structures. Despite fabrication advantages, its bulk mechanical and tribological properties are the main limitations for application as MEMS material. Carbon filler materials such as graphene, graphite and multi-walled carbon nanotube (MWCNT) are added to SU-8 for tribological and mechanical property enhancements. SU-8/(5 wt%) graphite composite has performed better for the steady-state coefficient of friction at all loads including for the speed effect. SU-8/(5 wt%) MWCNT has shown excellent wear resistance. At 10 wt% graphite content, SU-8/graphite is superior in tribological performance to other composites tested. [ABSTRACT FROM AUTHOR]

A mathematical model for transient photocurrent in X-ray imaging detectors has been developed by considering charge carrier trapping under exponentially distributed carrier generation across the photoconductor. The model for the transient and steady-state carrier distributions and hence the photocurrent has been developed by solving the carrier continuity equation for both holes and electrons. The model is applied to amorphous selenium (a-Se) detectors for both chest radiography and mammography. We analyze the transient rise and decay of the photocurrent profile as a function of time. The quick rise and decay parts, and then the slow rise and decay parts of the photocurrent profile are due to the hole and electron transports, respectively. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Photoconductivities in molybdenum disulfide (MoS) layered nanostructures with two-hexagonal crystalline structure prepared by mechanical exfoliation were investigated. The photoconductor-type MoS nanoflakes exhibit remarkable photoresponse under the above bandgap excitation wavelength of 532 nm at different optical intensity. The photocurrent responsivity and photoconductive gain of nanoflakes can reach, respectively, 30 AW and 103 at the intensity of 50 Wm, which are several orders of magnitude higher than those of their bulk counterparts. The vacuum-enhanced photocurrent and power-independent responsivity/gain indicate a surface-controlled photoconduction mechanism in the MoS nanomaterial. [ABSTRACT FROM AUTHOR]

In the pursuit of novel functionalities by utilizing the lattice degree of freedom in complex oxide heterostructure, the control mechanism through direct strain manipulation across the interfaces is still under development, especially with various stimuli, such as electric field, magnetic field, light, etc. In this study, the superlattices consisting of colossal-magnetoresistive manganites La0.7Sr0.3MnO3 (LSMO) and photostrictive SrRuO3 (SRO) have been designed to investigate the light-dependent controllability of lattice order in the corresponding functionalities and rich interface physics. Two substrates, SrTiO3 (STO) and LaAlO3 (LAO), have been employed to provide the different strain environments to the superlattice system, in which the LSMO sublayers exhibit different orbital occupations. Subsequently, by introducing light, we can modulate the strain state and orbital preference of LSMO sublayers through light-induced expansion of SRO sublayers, leading to surprisingly opposite changes in photoresistivity. The observed photoresistivity decreases in the superlattice grown on STO substrate while increases in the superlattice grown on LAO substrate under light illumination. This work has presented a model system that demonstrates the manipulation of orbital-lattice coupling and the resultant functionalities in artificial oxide superlattices via light stimulus. [ABSTRACT FROM AUTHOR]

We describe energy-dependent incomplete signal generation in semiconductor detectors with a simple planar geometry using deep charge trapping and depth-of-interaction models. Based on this formalism, we have characterized mercuric iodide (HgI_2) photoconductors by extracting performance parameters from x-ray-induced signals under mammographic imaging conditions. The HgI_2 sample photoconductors were prepared using a simple screen-printing method. For an x-ray tube output from tungsten target and 30-kV setting, the quantum absorption efficiency of samples with a thickness of approximately 0.1 mm was measured to be \sim 70\%. X-ray sensitivity was measured to be 0.4~\nC cm^ - 2 mR^ - 1. Mobility-lifetime products for electrons and holes were measured as \sim 2 \times 10^ - 6~\cm^2~\V^ - 1 and \sim 0.9 \times 10^ - 6~\cm^2~\V^ - 1, respectively. Considering incomplete charge collection, the W-value (or w) was estimated to be \sim 27 ~\eV. Since the characterization method described in this study is simple and does not require sophisticated equipment, it can be useful for the characterization of photoconductor materials. [ABSTRACT FROM AUTHOR]

This paper describes the properties of photoresistive sensors built on a thin silicon substrate. These fully restriction of hazardous substances compliant devices show high photo sensitivity, comparable to the best performing CdS/CdSe photocells, within a wide range of illumination intensities extending down to low illuminance levels of less than 5 lx of a black-body radiation at 2850 K color temperature. A comparative analysis of the photoconductive gain confirmed better efficiency of the devices with a shorter photoconductive channel length. The photoconductive gain was shown to increase with the illuminance level, exceeding unity at certain illuminance levels specific for the photoconductive channel length and applied voltage bias. Such behavior was suggested to occur due to the retardation of the minority carrier collection by the potential barrier formed by a high-low junction within the photoresistor's contact regions, which allows more than one majority carrier collection by the electrode per each collected non-equilibrium minority carrier. The physical mechanisms affecting the photocurrent and resistance dependence on the applied voltage bias and illumination intensity are discussed. [ABSTRACT FROM AUTHOR]

Materials displaying anomalous quantum confinement effects (aqce) comprise the significant materials for recent optoelectronics, two-dimensional (2D) heterojunctions and band-gap engineering. Although available literature involves numerous works for regular 2D materials, there is still a lack of the key physical properties of aqce materials. So, in this work, density functional theory (DFT) calculations have been performed for the electronic, optical, phonon and thermoelectric properties of bulk and monolayered counterparts of recently introduced RbLiS and RbLiSe (aqce) compounds. The bulk RbLiS demonstrated a bandgap of 2.53 eV, whereas its monolayer has a lower bandgap of 1.20 eV. In addition, the bulk bandgap of RbLiSe was determined to be 2.10 eV being higher than the 1.26 eV of its monolayered counterpart. The optical properties of the addressed compounds are reported to be complex in nature, where bulk RbLiS and monolayers of RbLiS and RbLiSe can be intended as low-dielectric materials. Also, both bulk and monolayered RbLiS and RbLiSe compounds may be used as demanded photoconductors for possible UV purposes. In addition, both bulk RbLiS and RbLiSe exhibit high-refractive indices and are determined to be feasible for practical IR goals in contrast to their monolayer counterparts. Also, both bulk and monolayered RbLiS and RbLiSe compounds can be used as effective optical absorbers in ultraviolet (UV) applications. Phonon dispersions indicated dynamical stability of both bulk and monolayered structures of RbLiS and RbLiSe, which means the possibility of their experimental synthesis. Bulk and monolayered structures of RbLiS and RbLiSe compounds with high Seebeck coefficients suggest the possibility of new thermoelectric materials from bulk (3000 μV/K) and monolayered (2200 μV/K) RbLiS and RbLiSe compounds. • Bulk RbLiS and RbLiS/RbLiSe monolayers can be intended as low-dielectric materials. • Bulk and monolayered RbLiS/RbLiSe may be used as photoconductors for UV purposes. • Bulk RbLiS/RbLiSe with high-refractive indices are suitable for practical IR goals. • Phonon dispersions suggest the experimental synthesis of all surveyed materials. • Bulk and monolayered RbLiS/RbLiSe compounds can be new thermoelectric materials. [ABSTRACT FROM AUTHOR]

Photolithographic processes of multilevel features in microfluidics can be complex and expensive. This paper demonstrates a quick method for manufacturing multilevel patterns, which is based on liquid crystal display masking during a standard lithography process for master mold fabrication for the polydimethysiloxane replica process. An active mask, based on a liquid crystal display, can simplify the process due to the ability to quickly modify designs and reduce the overhead for alignment between mask levels. The possibility of multilevel patterning, with the help of active masking, creates new opportunities for optical lithography processes. We have developed the process for a standard, mercury lamp exposure mask aligner system. The patterning characteristics were evaluated with a step pattern fabricated as an example of three-dimensional patterning for multilevel structuring. The application of a liquid crystal mask for resist contrast measurements was demonstrated. [ABSTRACT FROM AUTHOR]

Here, we present a self-powered graphene–MoS 2 hybrid phototransistor that simultaneously exhibits high responsivity, fast response rate and high on–off ratio. In this phototransistor, fewer-layer MoS 2 serves as a sensitizer to absorb light, and high mobility graphene serves as an expressway for carrier transport, an asymmetric metal contact (titanium and palladium) design is adopted to provide a strong internal electric-field in the phototransistor channel. Under light illumination, a photovoltage arises at the two asymmetric graphene/electrode interface with photodiode mechanism, which act as a bias voltage driving the large quantity of photocarriers injected from MoS 2 layer to transport in graphene channel with photoconductor mechanism. With this ingenious design, the hybrid phototransistor achieves a response rate of 0.13 ms and on–off ratio up to 1428 together with responsivity exceeding 3.0 A/W under zero bias operation. The hybrid phototransistor takes full the advantage of fast response rate of the photodiode and high responsivity of the photoconductor, which makes it has great potential for wide applications in optoelectronics, such as optical logic, optical computing and optical communication. [ABSTRACT FROM AUTHOR]

The first application of a commercial Terahertz quantum cascade laser (QCL) system for high resolution spectroscopy of supersonic beams is presented. The QCLs exhibited continuous linear voltage tuning over a 2 GHz range about a center frequency of 3.762 THz with ∼1 ppm resolution. A sensitivity of ∼1 ppm fractional absorption was measured with a single pass optical system. Multipass operation at the quantum noise limit of the stressed photoconductor detector would produce a 100-fold improvement. [ABSTRACT FROM AUTHOR]

We describe the preparation and propertiesof a coaxial, three-layer,gold-CdSe-gold nanowire 30 μm in length that functions as amonolithic photodetector. The gold (Au) electrode core of this sandwichstructure is prepared using the lithographically patterned nanowireelectrodeposition (LPNE) method on a glass surface. A CdSe shell ofdefined thickness, dCdSe, from 200 to280 nm is then electrodeposited on this Au nanowire. Finally, a conformalgold layer is electrodeposited on top of the CdSe shell. The two concentricgold electrodes within this architecture measure the photoconductivityof the ultrathin CdSe absorbing layer in the direction orthogonalto the nanowire axis. This architecture enables accelerated response/recoveryof the nanowire to light while simultaneously maximizing the photoconductivegain without relinquishing any of the photoresponsive area of a ”bare”nanowire. Characterization by scanning electron microscopy (SEM) offocused ion beam (FIB) cross sections together with electron dispersiveX-ray spectroscopy (EDS) reveal the distinct core–multishellnanostructure, layer thicknesses, and layer compositions. The position-dependentphotoresponse along the axis of the nanowire, probed using a laserspot, shows that the Au nanoshell significantly enhances the photocurrent.The performance of Au–CdSe–Au core–multishellnanowire photodetectors depend sensitively on the thickness of CdSenanoshell over the range of from 200 nm < dCdSe< 280 nm. The highest performance was obtained forthe dCdSe= 250 nm this device, whichshowed a photoconductive gain of 2172, a responsivity of 209 A·W–1, a response time of 17 μs, and a recovery timeof 96 μs. [ABSTRACT FROM AUTHOR]

We present an optocoupler device based on a blue organic light-emitting diode (OLED) as input unit, and a pentacene photoconductor as output unit. The optocoupler was realized on a transparent glass substrate. The luminance was found larger than 10 3 cd/m 2 with a blue peak emission at 450 nm for the optimized ZnO (120 nm)/ITO (150 nm)/α-NPB (40 nm)/BCP (15 nm)/Alq3 (20 nm)/Al structure. The I ds-Illum / I ds-Dark current ratio, the sensitivity and the current density transfer ratio of the optocoupler are of about 7, 10 −1 A/W, and 10 −1 , respectively. The rise as well as full times were found faster for high bias voltages. The equilibrium regime with less persistent current was reached more quickly, as evidenced by the fast current response for higher bias voltage, indicating a more favorable recombination processes of the charge carriers. The organic optocoupler with a blue OLED reveals promising results; thus, it can be investigated as a good candidates for practical uses in organic optoelectronic circuits with high bias voltages. [ABSTRACT FROM AUTHOR]

A simple and inexpensive method of monitoring the movement of an isolated frog heart provides comparable results to those obtained with a force transducer. A commercially available photoresistor is integrated into a Wheatstone bridge circuit, and the output signal is interfaced directly with a recording device. An excised, beating frog heart is placed in a Petri dish and over the photoresistor so that movements produced during the heartbeat cycle change the amount of light entering the photoresistor and, therefore, the voltage output from the circuit. Experiments that can be done with this system include the effects of temperature and dose-response relationships with Ringer's solutions containing acetylcholine and norepinephrine. [ABSTRACT FROM AUTHOR]

A review of articles like "One-Step Synthesis of [16]Helicene" by K. Mori, T. Murase and M. Fujita, "Toll-Like Receptor 7 Inactive Ligands Enhanced Cytokine Induction by Conjugation to Weak Antigens" by D. Gao, Y. Diao, W. Li, N. Gao, Y. Liu, Z. Wang, W. Jiang, and G. Jin, and "Electrodeposited Lamellar Photoconductor Nanohybrids Driven by Peptide Self-Assembly" by M. K. Manna, S. K. Pandey, I. Maity, S. Mukherjee, and A. K. Das is presented.

K2Hg2Se3, a new photoconductingmaterial with a direct band gap around 1.4 eV, was obtained in nearlyquantitative yields and large scale (50 g per batch) by means of solvothermaltreatment of a corresponding solid. The compound comprises covalentlylinked selenidomercurate columns that accommodate potassium counterions.Composition and structure allow for a specific combination of optoelectronic,photophysical, and thermoelectric properties, which initiates a systematicmaterial development within this family of compounds. [ABSTRACT FROM AUTHOR]

Owing to the special properties and wide applications, UV photodetectors based on wide-band-gap semiconductors have drawn an increasing interest during the last two decades. However, practical UV photodetectors are required two contradictory performances: high internal gain and fast recovery speed, because high internal gain is achieved by long life time of photoexcited carriers and fast recovery needs their fast decay. Their slow decay in wide-band-gap semiconductors has been known as a persistent photoconductivity (PPC) problem and hinders applications. In this paper, a good solution to the above contradictory problem is demonstrated on a single SnO2 microrod photoconductor, which shows both high photoconductive gain (≈1.5 × 109) and quick recovery speed (<1 s). Notably, the quick recovery speed is associated with the removal of the persistent photoconductivity effect (>1 d), which is induced by a novel 'reset' process: bending and straightening the microrod and subsequently applying a voltage pulse. This result suggests that SnO2 microrods have potential applications in high-performance UV photodetecting devices. [ABSTRACT FROM AUTHOR]

Compared to periodic crystals, quasicrystals have higher point group symmetry and are more favorable in achieving complete band-gaps. In this report, a top-cut prism interferometer is designed to fabricate ten-fold photonic quasicrystalline structures. By optimizing the exposing conditions and material characteristics, appropriate quasicrystals have been obtained in the SU8 photoresist films. Atomic Force Microscopy and laser diffraction are used to characterize the fabricated structures. The measurement results show the consistence between the theoretical design and experiments. This will provide guidance for the large-area and fast production of ten-fold quasicrystalline structures with high quality. [ABSTRACT FROM AUTHOR]

Aromatic organic molecules serve as optoelectronic materials owing to their intrinsic optical and electronic properties. Herein, self-assembled lamellar nanostructures as photoconductor hybrids, which are obtained from naphthalene-2-methoxycarbonyl (Nmoc)-capped peptide amphiphiles, are described. Hybrid nanostructures are constructed in a controlled manner by an electrochemical deposition technique in combination with the inorganic Zn(OH)2 phase. Inorganic Zn(OH)2 layers turn into semiconductor ZnO layers upon annealing at 150 °C and lamellar nanostructures are formed in a periodic manner. Synergistic effects of hydrogen bonding and π-π stacking interactions of aromatic peptide amphiphiles are the driving force for the formation of self-assembled lamellar nanostructures. Morphological, structural, and optical studies of such lamellar hybrid nanostructures are reported. Photoconduction of these hybrid nanostructures is also examined in detail. [ABSTRACT FROM AUTHOR]

We explore the electrical, optical, and structural properties of fast photoconductors of In0.53Ga0.47As containing a number of different rare-earth arsenide nanostructures. The rare-earth species provides a route to tailor the properties of the photoconductive materials. LuAs, GdAs, and LaAs nanostructures were embedded into InGaAs in a superlattice structure and compared to the relatively well-studied ErAs:InGaAs system. LaAs:InGaAs was found to have the highest dark resistivities, while GdAs:InGaAs had the lowest carrier lifetimes and highest carrier mobility at moderate depositions. The quality of the InGaAs overgrowth appears to have the most significant effect on the properties of these candidate fast photoconductors. [ABSTRACT FROM AUTHOR]

In this paper, issues associated with the development of infrared (IR) and terahertz (THz) radiation detectors based on HgCdTe are discussed. Two-color un-cooled and cooled to 78K narrow-gap mercury-cadmium-telluride semiconductor thin layers with antennas were considered both as sub-THz (sub-THz) direct detection bolometers and 3-10 μm IR photoconductors. The noise equivalent power (NEP) for one of the detectors studied at ≈140GHz reaches NEP300K ≈ 4.5-10 W/Hz1/2 and NEP78K 78K ≈ 5 X 10-9 W/Hz1/2. The same detector used as an IR photoconductor showed the responsivity at temperatures T=78K and 300K with signal-to-noise ratio S/N ≈750 and 50, respectively, under illumination by using IR monochromator and globar as a thermal source. [ABSTRACT FROM AUTHOR]

Fast and reversible modulation ofion flow through nanosized apertures is important for many nanofluidicapplications, including sensing and separation systems. Here, we presentthe first demonstration of a reversible plasmon-controlled nanofluidicvalve. We show that plasmonic nanopores (solid-state nanopores integratedwith metal nanocavities) can be used as a fluidic switch upon opticalexcitation. We systematically investigate the effects of laser illuminationof single plasmonic nanopores and experimentally demonstrate photoresistanceswitching where fluidic transport and ion flow are switched on oroff. This is manifested as a large (∼1–2 orders of magnitude)increase in the ionic nanopore resistance and an accompanying currentrectification upon illumination at high laser powers (tens of milliwatts).At lower laser powers, the resistance decreases monotonically withincreasing power, followed by an abrupt transition to high resistancesat a certain threshold power. A similar rapid transition, althoughat a lower threshold power, is observed when the power is insteadswept from high to low power. This hysteretic behavior is found tobe dependent on the rate of the power sweep. The photoresistance switchingeffect is attributed to plasmon-induced formation and growth of nanobubblesthat reversibly block the ionic current through the nanopore fromone side of the membrane. This explanation is corroborated by finite-elementsimulations of a nanobubble in the nanopore that show the switchingand the rectification. [ABSTRACT FROM AUTHOR]

A novel active-matrix driving circuit, consisting of a level-shifter in each pixel and low-voltage (5 V) vertical and horizontal scanning circuits, was simulated and fabricated as part of an effort to develop a flat image sensor consisting of a Spindt-type field emitter array (FEA) and a high-gain avalanche rushing amorphous photoconductor target for ultrahigh-sensitivity compact high-definition television (HDTV) cameras. Although the active-matrix driving circuit developed in our previous work could not drive the FEA quickly enough to meet the HDTV standard, the simulation and experimental results reported here show that the novel active-matrix driving circuit can shorten the response time and potentially meet the HDTV standard. [ABSTRACT FROM AUTHOR]

In this work a novel concept based on low power semiconducting, mid infrared components and new, low cost measurement cells for use in harsh environmental conditions, such as permafrost areas, is presented. Due to the small changes of the environmen tal carbon dioxide (CO 2 ) concentration in this area a high resolution of 5 ppm CO 2 is required. The current sensor design achieves a resolution of up to 6 ppm CO 2 and offers further optimization potential at overall low costs. [ABSTRACT FROM AUTHOR]

Thin-film Ge09Sn01 structures were grown by reduced-pressure chemical vapor deposition and were fabricated into photoconductors on Si substrates using a CMOS-compatible process. The temperature-dependent responsivity and specific detectivity (D*) were measured from 300 K down to 77 K. The peak responsivity of 1.63 A/W measured at 1.55 μm and 77 K indicates an enhanced responsivity due to photoconductive gain. The measured spectral response of these devices extends to 2.4 μm at 300 K, and to 2.2 μm at 77 K. From analysis of the carrier drift and photoconductive gain measurements, we have estimated the carrier lifetime of this Ge09Sn01 thin film. The longest measured effective carrier lifetime of 1.0 x 10-6 s was observed at 77 K. [ABSTRACT FROM AUTHOR]

In 1959, Lawson and co-workers published the paper which triggered development of variable band gap Hg1-xCdxTe (HgCdTe) alloys providing an unprecedented degree of freedom in infrared detector design. HgCdTe ternary alloy has been used for realization of detectors operating under various modalities including: photoconductor, photodiode, and metal-insulator-semiconductor detector designs. Over the last five decades, this material system has successfully overcome the challenges from other material systems. It is important to notice that none of these competitors can compete in terms of fundamental properties. The competition may represent more mature technology but not higher performance or, with the exception of thermal detectors, higher operating temperatures (HOTs) for ultimate performance. In the last two decades, several new concepts for improvement of the performance of photodetectors have been proposed. These new concepts are particularly addressing the drive towards the so called HOT detectors aiming to increase detector operating temperatures. In this paper, new strategies in photodetector designs are reviewed, including barrier detectors, unipolar barrier photodiodes, multistage detectors and trapping detectors. Some of these new solutions have emerged as a real competitor to HgCdTe photodetectors. [ABSTRACT FROM AUTHOR]

The present paper proposes a study, followed up by the implementation of a low cost and low power consumption fruit sorting system. The implemented system was tested for apple sorting. Under the tests we gained an accuracy of 100% from the correct sorting point of view, which emphasize the good functioning of the system proposed by us. [ABSTRACT FROM AUTHOR]

[Display omitted] • Si nanopillars are used as substrate for ZnS based photoresistor. • ZnS is deposited on the nanopillar surface by RF magnetron sputtering. • The ZnS/Si based photoresistors have stable photosensitive properties. • The nanopillars based photoresistor has the higher response than the planar one. It is the first time that the Zinc sulfide (ZnS) film is deposited on silicon (Si) planar and nanopillars surface for photoresistor application. The 200 nm thick ZnS layer is deposited by RF magnetron sputtering, and it can cover the planar and nanopillar Si surface tightly. Both the ZnS film on planar and nanopillar Si surfaces are well crystallinity from the XRD patterns. Compared with the ZnS film on the planar Si surface, the ZnS/ Si nanopillars structure has a lower reflection, and the response of the ZnS film on Si nanopillars is much higher than that on planar Si surface. [ABSTRACT FROM AUTHOR]