We report on photoconduction and optical properties of aligned assemblies core-shell CdSe/CdS nanorods prepared by a seeded growth approach. fabricate oriented layers drop casting the from solution substrates with prepatterned, micrometer-spaced electrodes obtain nanorod alignment due to coffee stain effect. The photoconductivity can be improved significantly an annealing process under vacuum conditions. spectral response photocurrent shows distinct features that assigned electronic level...

In this paper, shunt capacitive RF microelectromechanical systems (MEMS) switches are developed in III-V technology using tantalum nitride (TaN) and pentoxide (Ta <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> ) for the actuation lines dielectric layers, respectively. A compositional, structural, electrical characterization of TaN Ta films is preliminarily performed, demonstrating...

Digital holographic microscopy is an important interferometric tool in optical metrology allowing the investigation of engineered surfaces with microscale lateral resolution and nanoscale axial precision. In particular, microelectromechanical systems (MEMS) surface analysis, conducted by characterization, requires high accuracy for functional testing. The main issues related to MEMS inspection are superficial roughness complex geometry resulting from several fabrication steps. Here,...

We investigate the photodetection properties of individual core/shell GaAs/AlGaAs nanowires (NWs) and, in particular, their behavior under linearly polarized light. The NWs are grown by Au-assisted metalorganic vapor phase epitaxy and electrical contacts defined on electron beam induced deposition. spectral photocurrent single NW is measured dependence polarization anisotropy ρ (varying from ∼0.1 to ∼0.55) absorption wavelength found be clearly affected structure. High quantum efficiency...

The qualitative explanation by Loeb of the constancy amplification factor with increasing corona currents coaxial cylindrical electrodes used, as in conventional Geiger counters, is placed on a quantitative basis. As anticipated, it shown that screening action space charge which responsible for and stability average discharge current. fluctuations superposed constant current, previously reported us, are explained response system having definite resonance frequency to statistical...

Tetrapod-shaped CdSe(core)/CdTe(arms) colloidal nanocrystals, capped with alkylphosphonic acids or pyridine, were reacted various small molecules (acetic acid, hydrazine and chlorosilane) which induced their tip-to-tip assembly into soluble networks. These networks subsequently processed films by drop casting photoconductive properties studied. We observed that prepared from tetrapods coated phosphonic not photoconductive, but of the same exhibited appreciable photocurrents. On other hand,...

In this paper, the reliability of shunt capacitive radio frequency microelectromechanical systems switches developed on GaAs substrate using a III-V technology fabrication process, which is fully compatible with standard monolithic microwave integrated circuit fabrication, investigated. A comprehensive cycling test carried out under application different unipolar and bipolar polarization waveforms in order to infer how realized switches, still limited respect silicon-based devices due less...

Moderation of internal quantum mechanical energies, such as exchange energy an unconventional contact, comprised a system 2-D charge carriers, improves performance merits variable capacitors, varactors, mainly in tuning ratio (TR), and sensitivity, S. Energy transfer from the contact to dielectric increases density enhances capacitance varactor. Here, we analyze varactor based on planar metal-semiconductor-metal (MSM) structure with embedded layer high-density electron gas (2DEG). Through...

In this work, SiNx/a-Si/SiNx caps on conductive coplanar waveguides (CPWs) are proposed for thin film encapsulation of radio-frequency microelectromechanical systems (RF MEMS), in view the application these devices fifth generation (5G) and modern telecommunication systems. Simplification cost reduction fabrication process were obtained, using two etching processes same barrel chamber to create a matrix holes through capping layer remove sacrificial under cap. Encapsulating layers with etch...

Shunt capacitive RF MEMS switches have been developed using III-V technology and employing (tantalum pentoxide) Ta 2 O 5 thin films as dielectric layers. In order to evaluate the potential of for considered application, compositional, structural, electrical characterization deposited has performed, demonstrating that they are good candidates be used layers fabrication switches. Specifically, found show a leakage current density few nA/cm for<mml:math...

The potential of sputtered Ta2O5 thin films to be used as dielectric layers in capacitive radio frequency microelectromechanical system switches is evaluated by investigating two factors crucial importance for the performance these devices which are transport mechanisms and charging effects layer. We find that show good electrical dielectrical properties considered application terms a low leakage current density 4 nA/cm2 E=1 MV/cm, high breakdown field MV/cm constant 32. For electric fields...

Phototransport properties of organically capped colloidal CdSe quantum rod thin films deposited by spin coating are studied in air at room temperature planar electrode configuration. Under optical excitation, the observed current-voltage characteristics and current transients well described a resonant tunneling model. A significant irreversible quenching photoresponse occurs with either aging samples or flowing itself when above few picoamperes. The process, which is still interpreted frame...

We report on a variable capacitor that is formed between Schottky contacts and the two dimensional electron gas (2DEG) in planar metal-semiconductor-metal structure. Device capacitance at low bias twice series of anode cathode, enhancing to maximum value, Cmax, threshold voltage, before reaching minimum, Cmin, lower than geometric coplanar contacts, thus resulting ultra high Cmax/Cmin tuning ratio. Sensitivity, normalized change with also very large. The dense reservoir 2DEG charge...

Capacitance of capacitors in which one or both plates are made a two-dimensional charge system (2DCS) can be increased beyond their geometric structural value. This anomalous capacitance enhancement (CE) is consequence manipulation quantum mechanical exchange and correlation energies the ground state energy 2DCS. Macroscopically, it occurs at critical densities corresponding to transition from an interacting "metallic" noninteracting "insulator" mode 2-D system. Here, we apply this concept...

Conductivity and photoconductivity properties of individual GaAs/AlGaAs core-shell nanowires (NWs) are reported. The NWs were grown by Au-assisted metalorganic vapor phase epitaxy, then dispersed on a substrate where electrical contacts defined the electron beam induced deposition. Under dark conditions, carrier transport along NW is found to be limited Schottky contacts, influenced presence an oxide layer. Nonetheless, under illumination, shows significant photocurrent, much higher than...

Low temperature growth of GaAs (LT-GaAs) near 200 °C results in a recombination lifetime nearly 1 ps, compared with approximately ns for regular ~600 grown (RT-GaAs), making it suitable ultra high speed detection applications. However, LT-GaAs detectors usually suffer from low responsivity due to carrier mobility. Here we report electro-optic sampling time response measurements detector that employs an AlGaAs heterojunction, thin layer LT-GaAs, channel RT-GaAs, and vertical electric field...

A detailed study of the electrical properties planar AlGaN/GaN Schottky diodes is presented, focus being on role two dimensional electron gas (2DEG) depletion and non-idealities in different voltage regimes. The 2DEG behavior inferred from analysis capacitance current measurements with transition vertical to lateral diode operation occurring at Vpinch-off = 4 V. In particular, sub-micrometer width, laterally extending edge contact under high reverse voltages, evaluated basis a simple fringe...

An experimental and theoretical investigation on the electronic structure of double layer InAs∕GaAs quantum dots (QDs) is presented. In order to evaluate effects coupling between zero-dimensional states, spacer separating two QD layers varied from 4.5to10nm. The quantitative comparison experiment theory obtained by a previously proposed single band effective masslike model, where input parameter values are given systematic morphological, structural, spectroscopic samples. Although QDs...

We develop shunt capacitive RF MEMS switches in III-V technology making use of materials which can be alternative to the ones commonly used, order overcome some technological constraints concerning reliability. Specifically, we evaluate potential tantalum nitride (TaN) and pentoxide (Ta₂O₅) used for actuation pads dielectric layers, respectively. To this scope, a compositional, structural electrical characterization TaN Ta₂O₅ films as function...

Simultaneous photoluminescence (PL) and external quantum efficiency (EQE) confocal mapping is used to investigate the correlation between local PL EQE in a regioregular poly(3-exylthiophene):poly(9,9-dioctylfluorene-co-benzothiadiazole) inverted bulk heterojunction solar cell. We show that charge generation collection are strongly non-uniform on length scale up 100 μm. Our results evidence organic cells optimization requires not only control of submicrometric active materials arrangement but...