Characterization of Cu/PAr/CdS MIS structure for sensor applications

In this study, electrical characterization of. the Cu/PAr/CdS MIS structures were made for sensor application. The main electrical parameters of MIS structure such as the ideality factor (n), barrier height (phi(B)), series resistances (Rs) and interface state density (Nss) were determined at various environments. The series resistance of structures was found 696 Omega and 818 Omega respectively at atmosphere and chloroform environments. It is observed the structure is suitable for sensor applications. Examination of gas sensing property of diode, I-V measurements were done in chloroform atmosphere and constant voltage measurements were done at different gas atmosphere. With the exposure of chloroform, the resistance of diode increases and with discontinuation of gas flow, diode was reverted back to its initial. Therefore, it was understood that the diode was suitable for the sensor applications

Electron Beam Dose and PMMA Thickness Dependent Circularity and Diameter Analysis of Au Nanodots

Background: The electrical and optical properties of nanoparticle-based devices depend on the shape, dimension and uniformity of these particles

Au/PAr/n-CdS/ITO polymer insulated MIS structure

In this work, we present optical, structural and electrical characterizations of Au/PAr/CdS metal interlayer semiconductor diode (MIS) structure by X-Ray diffraction (XRD), ultraviolet-visible (UV-vis) spectroscopy and curent-voltage (I-V) measurements at room temperature and in the dark. CdS was deposited onto ITO substrates by spray pyrolysing method, PAr was coated over CdS by drop-casting method and a gold metal contact was evaporated by e-beam evaporation system. The barrier height of Au/CdS (MS) structure was calculated to be 0,48eV. The barrier height of Au/PAr/CdS MIS structure was found different from that of the SBH value of Au/CdS MS structure. For the Au/PAr/CdS (MIS) structure, the barrier height, phi(B), and ideality factor, n, have been calculated as 0.61 eV and 2,25, respectively, from forward bias I-V measurements. The higher ideality factor attributed to the series resistance, R-s was calculated as 907.4 k Omega and 897.1 k Omega from Cheung functions. The effective barrier height, phi(B), and the series resistance, R-s, of the Au/PAr/CdS structure were also calculated using Norde method and found to be as 0.74 eV. and 974 k Omega respectively. The interface state density (N-ss) were obtained from the forward bias I-V characteristics at a region changing from 4x10(15) eV(-1)cm(-2) to 1x10(15) eV(-1)cm(-2). The charge transport mechanism of the structure were determined by the power law behaviour of the current with different exponent I proportional to Vm+1 were determined and three main slopes were found

Well-ordered nanoparticle arrays for floating gate memory applications

A non-volatile floating gate memory device containing well-ordered Au nanoparticles (NPs) is fabricated as a metal-oxide-semiconductor capacitor structure. With superior control on the size, shape and position of nanoparticles, the presented nano-floating gate memory (NFGM) device possesses almost perfect precision of device geometry. The well-ordered Au NPs embedded within the memory device exhibit large memory window at low operation voltages (8.8V @ 15V), fast operation time (<10(-4) s) and good retention (up to 10(7) s). In this work, the structural properties of the NFGM device are correlated with the examined electrical properties. The current results are compared with the other studies in the literature to emphasis the advantages of the precise ordering and geometry of the NPs

Optical Properties of Polyaniline Synthesized by Oxidative Polymerization and Electrical Characterization of Ag/PANI/PEDOT:PSS/Ag Structures

Polyaniline was synthesized in the presence of aniline hydrochloride and ammonium peroxydisulfate in water solution. The type of majority charge carriers in polyaniline was determined by hot probe measurement setup and it was found that polyaniline behaves as p-type semiconductor. This compound has been characterized by FT-IR, together with SEM and UV-Vis spectral data. The electronic properties of the PANI have been studied by fabricating metal polyaniline metal (MIM) capacitors. It was observed that the insertion of Poly(3,4 ethylenedioxythiophene):poly(styrenesulfonate) conducting layer between Ag electrode and PANI modifies the current voltage characteristics of the Ag/PANI/Ag structure. The non-linear behavior of In(IIV) versus V-1/2 and In(IIV2) versus In(1/V) plots indicated that the thermoionic emission theory can be applied to evaluate junction parameters for the Ag/PANI/PEDOT:PSS/Ag structure. The Cheung's and Norde method, combined with conventional forward I-V, was used to extract the electronic parameters such as, barrier height, ideality factor and series resistance values

Improvement of fill factor by the utilization of Zn-doped PEDOT:PSS hole-transport layers for p-i-n planar type of perovskite solar cells

Poly (3,4-ethylenedioxythiophene)-poly (styrene sulfonate (PEDOT:PSS) is a widely-known conductive polymer mixture that is mostly engaged as a hole transport layer (HTL) in organic and perovskite so-lar cells (PSCs). In this study, it has been demonstrated that the use of Zn as an additive in PEDOT:PSS solution improved the photovoltaic performance of the ambient air solution-based fabrication of methy-lammonium lead tri-iodide (MAPbI(3)) based devices. The short circuit current density (JSC) of the device increased from 15.4 to 17.2 mA/cm(2), while the fill factor (FF) improved from 0.70 to 0.83 by using Zn-doped PEDOT:PSS as a hole transport layer (HTL), which is a record value for only gamma-butyrolactone (GBL) based MAPbI(3) PSCs. Additionally, open-circuit (VOC) value is boosted up from 890 to 925 mV by Zn-doping, which might be linked to the increased work function of the investigated HTLs. Moreover, the synergetic effect of improved electrical conductivity and hole mobility of PEDOT:PSS film and decreased the trap density of perovskite led to an increase of 37% in power conversion efficiency (PCE) and the stability of the inverted planar PSCs. (C) 2021 Elsevier Ltd. All rights reserved

Dielectric Response and Capacitance Measurements of Ag/ PVAc-Si /p-Si Structure

In this study, the effect of Poly(vinyl acetate) latex with Silicone surfactant (shortly PVAc-Si) thin film on the dielectric and capacitance-voltage properties of Ag / PVAc-Si /p-Si (MIS) structure were investigated. The dielectric characterization was obtained by impedance spectroscopy technique between 40 Hz-110 MHz at room temperature. The capacitance-voltage measurements were performed to clarify the flat band voltage of the sample. The frequency dependence of the real and imaginary parts of the complex impedance function indicated a space charge polarization. The Nyquist plots confirmed a single Debye type relaxation. The real and imaginary components of the complex dielectric function implied the effect of the grain and grain boundary effects in the material. Alternative current (ac) conductivity versus frequency curve of the structures displayed two different conductivity regimes. Nearly dc conductivity for the low frequencies and the dispersive region of the high-frequency band was obtained. The increase in ac conductivity with increasing frequency has been explained in the context of the Quantum Mechanical Tunneling (QMT) mechanism for PVAc-Si film-induced devices. According to the capacitance-voltage measurement, it is also shown that there is a hysteresis for flat band capacitance in between the applied forward and reverse voltage. Reduction of this hysteresis is achieved by the applied voltage across terminals of the PVAc-Si film-induced MIS structure. This controllable reduction in hysteresis may find a place in an application for floating gate memory devices. This study also provides to understand the effect of insulator layer thickness on the dielectric behavior of MIS devices

Surface acoustic wave quasi-Bessel beams generated by symmetrically tilted interdigital transducers

Formation of surface acoustic wave (SAW) quasi-Bessel beams on a piezoelectric substrate through superposition of plane waves generated by interdigital transducers tilted symmetrically about the propagation axis is numerically and experimentally demonstrated. Acting as an axicon, the tilted transducers provide a facile way for quasi-Bessel beam generation. Finite-element method simulations reveal that non-diffracting Bessel beams, whose length and width are 193 and 1.38 wavelengths, respectively, can be obtained on a YX-128(circle) lithium niobate substrate for an axicon angle of 15 degrees. The corresponding values for 20 degrees are 146 and 1.05 wavelengths, respectively. For a wavelength of approximately 300 micrometers, transmission spectra show that Bessel beam formation can be achieved at frequencies around 13.3 MHz. Bessel beam is visualized through a thin liquid film of methanol on the substrate. SAW Bessel beams can be utilized in acoustophoresis in microfluidic systems and sensing applications

V-groove etched 1-eV-GaInNAs nipi solar cell

Simulated and experimental properties of a Ga(1-x)In(x)As(1-y)N(y)nipi solar cell involving V-grooves for contact formation are reported. In particular, using a drift-diffusion model, we simulate the conversion efficiency, the short-circuit current density (J(SC)), and the open-circuit voltage (V-OC) as a function of the number of nipi junctions. Based on the modelling results, optimized nipi solar cell incorporating five n-p junction pairs was grown on a p-type GaAs (100) substrate using molecular beam epitaxy (MBE). The bandgap of the nipi structure was determined to be 1eV. The metal contacts of the nipi solar cell structure were processed in the form of mesa and V-groove. These shapes enable both vertical and horizontal carrier transport within the solar cell. The effect of thermal annealing on J-V characteristics of both type of devices is finally assessed. The results point out that the V-groove sample has better photovoltaic characteristics than the mesa structure sample

Effect of thermal annealing and nitrogen composition on quantum transport in GaInNAs alloy based modulation doped quantum well structures

Effect of thermal annealing on quantum transport properties have been investigated on as-grown and annealed n-type modulation doped GaInNAs/GaAs quantum well (QW) structures with various nitrogen concentration in low (B < 0.1 T) and high magnetic field (up to 18 T) regions between 75 mK and 1 K. We have observed pronounced plateaus in quantum Hall effect results. The shape of the plateaus do not have a temperature-dependent characteristic for both as-grown and annealed samples. On the other hand, because electron mobility decreases with increasing nitrogen concentration and enhances upon annealing process, the plateaus have more flattened characteristic. The temperature-dependent low field magnetoresistance measurements reveal that the samples exhibit weak antilocalization, which is affected from nitrogen concentration and thermal annealing. Electronic transport parameters such as spin coherence, phase coherence and elastic scattering times, Rashba parameter and spin-splitting energy are extracted from low field magnetoconductivity plots. It is shown that dilute amount of nitrogen composition is an important parameter, which affects the strength of the spin-orbit interaction due to the strongly localized electron states and disorder-induced electron momentum scattering. The longest spin relaxation time is observed for the sample with the highest nitrogen composition and the lowest electron mobility. The calculated Rashba parameter, spin-orbit splitting energy and spin relaxation time for as-grown and annealed samples reveal that thermal annealing causes a decrement in these parameters, but increasing nitrogen composition leads to an increase in spin relaxation time. Therefore both nitrogen composition and thermal annealing can be used to manipulate the spin-orbit coupling strength in GaInNAs-based modulation doped QW structures. (C) 2016 Elsevier B.V. All rights reserved