Frequency-dependent Electrical Characteristics Research Articles

Voltage- and Frequency-Dependent Electrical Characteristics and Interface State Density of Ni/ZnO Schottky Diodes

Voltage- and Frequency-Dependent Electrical Characteristics and Interface State Density of Ni/ZnO Schottky Diodes

Photoluminescence, Impedance, Thermal Characteristics and Hirshfeld Surface Analysis of Potassium Bisulphate Single Crystals for Third Order NLO Applications

Good quality potassium bisulphate (KHS) single crystals have been grown by slow evaporation method at room temperature. The KHS crystal was found to be crystallizing in orthorhombic crystal structure with Pbca space group. The photoluminescence behaviour of the crystal was analysed in the visible region. This study disclosed that the grown KHS crystal has intense blue emission peak at 490 nm. Impedance analysis was performed to investigate the frequency dependent electrical characteristics at various temperatures. From the impedance studies the bulk resistance, grain boundary resistance and DC conductivity values of the grown crystal were found out. The KHS crystal was subjected to TGA/DTA and the results have been investigated. The electrical parameters like Fermi energy and average energy gap of KHS crystal have been determined. The evaluated values are used to estimate the electronic polarizability. The intermolecular interactions were predicted using Hirshfeld surface analysis. This analysis exhibited that the utmost contribution to the crystal structure was the K⋯O (46.7%) interaction. The 2D fingerprint plot provides the percentage contribution of each atom-to-atom interaction. Since KHS material is a centrosymmetric crystal, it could be used for third order nonlinear optical (NLO) applications.

Facile Zinc Oxide Nanoparticle Green Synthesis Using Citrus reticulata Extract for Use in Optoelectronic Sensors

Waveguides are structures that can be used as sensors. After adding a cladding of a proper material, waveguides can be used for detecting specific chemical species. In particular, high band gap oxide semiconductors can be used as cladding for optical waveguides. In these materials, the synthesis processes are expensive or contaminant generators, for this reason novel approaches are required. This work addresses a simple synthesis method for the preparation of zinc oxide nanoparticles using Citrus reticulata extract. XRD presented only the wurtzite structure for the zinc oxide nanoparticles, while TEM showed size and shape homogeneity. The ZnO band gap was lower than commercial ZnO. Using a computer simulation and frequency dependent electrical characteristics, a waveguide model was tested. The resulting characteristics presented great parameters for using in optoelectronic sensors. Resulting ZnO NPs have negligible amounts of green matter afterwards, making this a non-toxic method. As a result, herein presented synthesis is a promising method for developing new optoelectronic sensors. These devices can be used for automatic detection of chemical species by automated systems.

A detailed study on frequency dependent electrical characteristics of MOS capacitors with dysprosium oxide gate dielectrics

Frequency dependent electrical characteristics of Al/Dy2O3/p-Si/Ag MOS capacitors have been systematically investigated incorporating interfacial chemical structures of the capacitors to specify where interface state signals arise from. The results show that capacitance (C) increases with decreasing in the applied voltage frequency due to the response time dependency of the interface states. Conductance (G) curves have a single peak at the relatively high frequencies as expected. Interestingly, the G curves exhibit two distinct peaks at 400 kHz and lower frequencies. These G peaks are associated with acceptor-like interface (Dit,ac) and donor-like interface (Dit,dn) states. Electrochemical analysis has also depicted that non-stoichiometric DySiOx and SiOx bonds are present at the interface between Dy2O3/Si gate stack. Owing to interactions between mobile charge carriers and possible defect sites present at the DySiOx and SiOx, the Dit,ac and Dit,dn signals have been observed at G curves. In addition, the C hysteresis loop widths decrease with decreasing in the voltage frequencies due to opposite polarity and response time dependencies of the Dit,ac and Dit,dn states. The oxide, interface and border trap densities of capacitors exhibit slight frequency variations and their orders are comparable with device used in the state of the art microelectronics technologies. On the other hand, barrier potential varies from 0.97 eV to 1.136 eV depending on the voltage frequencies. Leakage current density was found to be 1.61 × 10−7 Acm−2 at −1 V and Fowler–Nordheim tunneling mechanism dominates the leakage current conduction. Considering to these results, it can be concluded that the Dy2O3 shows promising dielectric and insulating behavior for the application in future microelectronics technology.

Frequency and voltage dependent electrical and dielectric properties of Ag/nGO doped PVA/p-Si sandwich structure at room temperature

In present study, we investigated frequency and voltage dependence of electrical and dielectric properties of Ag/nGO doped poly(vinyl alcohol) (PVA)/ p-Si structures. The nGO-PVA films were prepared by using improved Hummers method and this thin film layers were analyzed with SEM and EDX. The main parameters as ideality factor (n), barrier height (Φbo) and saturation current (I0) were obtained from current–voltage (I-V) measurements. The frequency dependent electrical characteristics of structure investigated using capacitance–voltage (C–V) and conductance–voltage (G/ω–V) measurements in the frequency range of 10 kHz to 1000 kHz in 300 K absolute temperature. The capacitance, conductance and series resistance (RS) values decreased with increasing frequency. These decreases at higher frequencies are attributed to existence of interface state densities. The presence of the interface state densities (NSS) are also evidenced as a peak in the capacitance, conductance and series resistance–frequency characteristics. After, the dielectric properties of Ag/GO-PVA/ p-Si structures were obtained using C–V and G/ω–V measurements in the same frequency ranges. The values of dielectric constant (ε′), dielectric loss (ε″), and loss tangent (tanδ) decreases with increasing frequency while ac electrical conductivity (σac) increase with increasing frequency. Our results showed that frequency dependent electrical and dielectric properties were strongly frequency and voltage dependent.

Preparation of (CuS–PVA) interlayer and the investigation their structural, morphological and optical properties and frequency dependent electrical characteristics of Au/(CuS–PVA)/n-Si (MPS) structures

Structural, morphological and optical properties of prepared CuS nanostructures were analyzed using XRD, SEM, FTIR, UV–Vis and DRS methods. Experimental results indicated that samples show good crystalline structures. In addition, the particles size and their morphology changed with pH value. UV–Vis absorption shifts to blue by variation of pH and also both the diffuse reflectance and optical absorption of CuS nanostructures have absorption regions of 300–400 nm, respectively. Electrical characteristics of these structures were also investigated in the frequency range of 2 kHz–1 MHz by using impedance–voltage (Z–V) measurements. Experimental results showed that both the value of capacitance (C) and conductance (G/ω) are strong functions of frequency and voltage especially in depletion and accumulation regions due to the effects of surface states (Nss), series resistance (Rs) and interfacial (CuS–PVA) polymer layer. G/ω–V plot revealed a distinctive peak for each frequency in depletion layer and peak positions shift towards to accumulation region with increasing frequency. The voltage dependent profile of the Nss was found from the high–low capacitance (CLF–CHF) and Hill–Coleman methods and obtained values are agreeing with each other. The voltage dependent profile of Rs was also obtained using the Nicollian–Brews method and it decreases with increasing frequency. The obtained mean value of Nss was found at about 2 × 1011 eV−1 cm−2, which is lower and reasonable for an electronic device. Obtained lower values of Nss can be attributed to the passivation effect of the (CuS–PVA) polymer layer.

Thermal phase separation of ZrSiO4 thin films and frequency- dependent electrical characteristics of the Al/ZrSiO4/p-Si/Al MOS capacitors

In this work, the thermal phase separation and annealing optimization of ZrSiO4 thin films have been carried out. Following annealing optimization, the frequency-dependent electrical characteristics of the Al/ZrSiO4/p-Si/Al MOS capacitors were investigated in detail. The chemical evolution of the films under various annealing temperatures was determined by Fourier transform infrared spectroscopy (FTIR) measurements. The phase separation was determined by x-ray diffraction (XRD) measurements. The electrical parameters were determined via the capacitance–voltage (C–V), conductance–voltage (G/ω) and leakage-current–voltage (Ig–Vg). The results demonstrate that zirconium silicate formations are present at 1000 °C annealing with the SiO2 interfacial layer. The film was in amorphous form after annealing at 250 °C. The tetragonal phases of ZrO2 were obtained after annealing at 500 °C. When the temperature approaches 750 °C, transitions from the tetragonal phase to the monoclinic phase were observed. The obtained XRD peaks after 1000 °C annealing matched the crystalline peaks of ZrSiO4. This means that the crystalline zirconium dioxide in the structure has been converted into a crystalline silicate phase. The interface states increased to 5.71 × 1010 and the number of border traps decreased to 7.18 × 1010 cm−2 with the increasing temperature. These results indicate that an excellent ZrSiO4/Si interface has been fabricated. The order of the leakage current varied from 10−9 Acm−2 to 10−6 Acm−2. The MOS capacitor fabricated with the films annealed at 1000 °C shows better behavior in terms of its structural, chemical and electrical properties. Hence, detailed frequency-dependent electrical characteristics were performed for the ZrSiO4 thin film annealed at 1000 °C. Very slight capacitance variations were observed under the frequency variations. This shows that the density of frequency-dependent charges is very low at the ZrSiO4/Si interface. The barrier height of the device varies slightly from 0.776 eV to 0.827 eV under frequency dispersion. Briefly, it is concluded that the devices annealed at 1000 °C exhibit promising electrical characteristics.

Frequency dependent electrical characteristics and origin of anomalous capacitance–voltage (C–V) peak in Au/(graphene-doped PVA)/n-Si capacitors

Au/(7% graphene-doped PVA)/n-Si capacitors were fabricated and their electrical characteristics were investigated using complex impedance spectroscopy method (ISM) in the wide frequency range at room temperature. Experimental results show that the values of capacitance (C) and conductance (G/ω) decrease with increasing frequency. Such behavior of these parameters, especially at low frequencies, was attributed to the surface polarization; surface states (Nss) and their relaxation time (τ). Main electrical parameters such as doping concentration of donor atoms (ND) and barrier height (ΦB(C–V)) were obtained from the reverse bias C−2–V plots for various frequencies. While the value of ND decreases, ΦB(C–V) increases with increasing frequency. The large values of C especially at low frequencies were attributed to the high dielectric graphene-doped PVA. C–V plots in depletion region show a distinctive anomalous peak such that its intensity increases with increasing frequency whereas its position shifts toward negative biases due to the effects Nss and series resistance (Rs). The plots of Nss versus V and Rs versus V are also obtained using low–high frequency capacitance (CLF–CHF) and Nicollian and Brews methods, respectively. Obtained results are promising considering the performance of capacitors in storing large amounts of charge, thus 7% graphene-doped PVA can be used as an alternative material for replacement of conventional silicon dioxide (SiO2).

ELECTRICAL PROPERTIES OF Al/p-Si STRUCTURE WITH Al2O3 THIN FILM FABRICATED BY ATOMIC LAYER DEPOSITION SYSTEM

Al2O3 insulator layer was deposited by atomic layer deposition (ALD) technique on p-type Si [Formula: see text] and the Al/Al2O3/p-Si metal/insulator/semiconductor (MIS) structures were fabricated. The current–voltage ([Formula: see text]) characteristics of these structures were investigated in two different temperatures. The main electrical parameters such as the ideality factor ([Formula: see text]), zero bias barrier height ([Formula: see text]), and series resistance ([Formula: see text]) values were found for 300 and 400[Formula: see text]K. The energy density distribution profiles of the interface state density ([Formula: see text]) were determined from the [Formula: see text] characteristics. In addition, the capacitance–voltage ([Formula: see text]) and conductance–voltage ([Formula: see text]) characteristics of devices were investigated in the frequency range 50–1000[Formula: see text]kHz at room temperature. Frequency-dependent electrical characteristics such as doping acceptor concentration ([Formula: see text]), energy difference between the valance band edge and bulk Fermi level ([Formula: see text]), diffusion potential ([Formula: see text]), barrier height ([Formula: see text]), the image force barrier lowering ([Formula: see text]), maximum electric field ([Formula: see text]), and [Formula: see text] values were determined using [Formula: see text] and [Formula: see text] plots. In addition, the [Formula: see text] values were performed using Hill–Coleman method. According to experimental results, the locations of [Formula: see text] and [Formula: see text] have an important effect on [Formula: see text], [Formula: see text] and [Formula: see text] plots of MIS structure.

Origin of forward bias capacitance peak and intersection behavior of C and G/w of Ag/p-InP Schottky barrier diodes

Frequency-dependent electrical characteristics of Ag/p-InP diodes have been determined using impedance spectroscopy at room temperature. Series resistance (Rs) and interface state(s) (Nss) values were extracted from capacitance (C) and conductance (G/w) data using the Nicollian and Goetzberger and Hill–Coleman methods, respectively. C and G/w data were also corrected in the whole measured bias voltage range to obtain real diode capacitance Cc and conductance Gc values in order to see the effects of Rs. Both the C–V and Rs–V plots showed anomalous peak in depletion region especially at low frequencies due to the existence of Nss. C–V and G/w–V plots crossed at a certain bias voltage and this point shifted toward negative bias voltages with increasing frequency and then disappeared at 3MHz. Also, decrease in C values corresponds to an increase in G/w values in the same bias voltages.

Effect of the frequency and temperature on the complex impedance spectroscopy (C–V and G–V) of p-ZnGa2Se4/n-Si nanostructure heterojunction diode

X-ray diffraction pattern and AFM results confirm the nanostructure of p-ZnGa2Se4/n-Si. The unit cell lattice parameters, the crystallite size L, the dislocation density δ, and the main internal strain e were calculated. The temperature and frequency-dependent electrical characteristics of the Al/p-ZnGa2Se4/n-Si/Al heterojunction diode (HJD) have been investigated to determine the interface states which are responsible for the non-ideal behavior of the characteristics of the diode. The capacitance–voltage (C–V), conductance–voltage (G–V), and series resistance–voltage (Rs–V) characteristics of the diode have been analyzed in the frequency range of 5 kHz–1 MHz and temperature range of 303–423 K. The interfaces states of the diode were determined using conductance–voltage technique. The interface state density profile for the diode was obtained as a function of temperature and frequency. The values of the built-in potential Vbi, the doping concentration Nd and the barrier height φb(C–V) of the diode were calculated at different temperatures and frequencies. Our experimental results revealed that both the series resistance and interface state density values must be taken into account in studying the impedance spectroscopy of HJD to stand up their performance for electronic applications characteristics.

The frequency-dependent electrical characteristics of interfaces in the Sn/p-Si metal semiconductor structures

Abstract The purpose of this paper is to investigate frequency-dependent electrical characteristics of the interface states in Sn/p-Si metal semiconductor (MS) Schottky structures. To yield quantitative information about their frequency (f) and voltage (V) dependent characteristics, Sn/p-Si MS structures have been studied by using capacitance (C) and conductance (G/ω) measurements over a wide range of frequencies (50 kHz–1 MHz). The increase in capacitance at lower frequencies is seen as a signature of interface states, and the densities of which are evaluated to be of the order of ≅1010 cm−2 eV−1. The presence of the interfaces states (NSS) is also evidenced as a peak in the capacitance–frequency characteristics that increases in magnitude with decreasing frequencies. Furthermore, the voltage and frequency dependence of series resistance (RS) were calculated from the C–V and G/ω–V measurements and plotted as functions of voltage and frequency. The effect of RS on C and G/ω is found noticeable at high frequencies. The C–V–f and G/ω–V–f characteristics of studied structures show fairly large frequency dispersion especially at low frequencies due to NSS in equilibrium with the semiconductor. The experimental values of interface state densities and series resistance from C–V–f and G/ω–V–f measurements were obtained in the ranges of 3.46 × 1010−1.26 × 109 cm−2 eV−1 and 71.1–57.3 Ω, respectively. Experimental results show that both the RS and NSS values should be taken into account in determining frequency-dependent electrical characteristics.

Frequency dependent electrical characteristics of PbS quantum dots

PbS quantum dots (bare and silica coated) have been synthesized in PVA matrix with average size 10 nm and 9 nm. The capacitance-voltage (C − V ) and current -voltage (I − V )r esponse of both bare and coated quantum dots have been recorded in different frequency range (Hz-MHz). Both the samples show frequency dependent response except in case of C − V characteristics at MHz range. The I −V responses at low frequency range exhibit step like structures which could be attributed to 'Coulomb blockade'. PACS. 73.63.Kv Quantum dots - 82.35.Np Nanoparticles in polymers - 61.05.cp X-ray diffraction

On the profile of frequency and voltage dependent interface states and series resistance in MIS structures

The variation in the capacitance–voltage ( C– V) and conductance–voltage ( G/ ω– V) characteristics of Au/SiO 2/n-Si metal–insulator–semiconductor (MIS) structure have been systematically investigated as a function of frequencies in the frequency range 0.5 kHz–10 MHz at room temperature. In addition, the forward and reverse bias current–voltage ( I– V) characteristics of this structure were measured at room temperature. The high value of ideality factor was attributed to the high density of interface states localized at Si/SiO 2 interface and interfacial oxide layer. The density of interface states ( N ss) and the series resistance ( R ss) were calculated from I– V and C– V measurements using different methods and the effect of them on C– V and G/ω– V characteristics were deeply researched. At the same energy position near the top of valance band, the calculated N ss values, obtained without taking into account the series resistance of the devices almost one order of magnitude larger than N ss values obtained by taking into account R ss values. It is found that the C– V and G/ω– V curves exhibit a peak at low frequencies and the peak values of C and G/ ω decrease with increasing frequency. Also, the plots of R s as a function of bias give two peaks in the certain voltage range at low frequencies. These observations indicate that at low frequencies, the charges at interface states can easily follow an AC signal and the number of them increases with decreasing frequency. The I– V, C– V and G/ ω– V characteristics of the MIS structure are affected not only with R s but also N ss. Experimental results show that both the R s and C o values should be taken into account in determining frequency-dependent electrical characteristics.

Frequency-dependent electrical characteristics of DNA using molecular dynamicssimulation

Research on DNA has been widely carried out as a promising material fornanoelectronics, medicine development and disease diagnosis, using experiment,simulation and theory. We have carried out molecular dynamics simulationcoupled with the linear response theory, based on the time-correlation functionof an observable, in order to extract the frequency-dependent electricalcharacteristics of DNA. We observe a dielectric relaxation at around 50 MHz inthe case of octamers-DNA, which corresponds to a delta-relaxation. We alsoobserve dielectric relaxation in the case of mixtures of DNA, water molecules andions, given by the superposition of the individual dielectric relaxations of theDNA and the bulk-like water, at frequencies of about 50 MHz and 10 GHz,respectively.

Some Properties of Videopulse Soil-Layer Scattering with Continuous Variation in Frequency-Dependent Electrical Characteristics

Some Properties of Videopulse Soil-Layer Scattering with Continuous Variation in Frequency-Dependent Electrical Characteristics

Frequency-dependent electrical characteristics of GaAs MESFETs

Output resistance and transconductance of GaAs MESFETs have been observed to change significantly at very low frequencies. Extensive measurements of these characteristics as a function of device bias are reported. Direct measurements of the dispersive behavior between DC and 100 kHz and over a broad temperature range have been made on ion-implanted monolithic microwave IC (MMIC) devices. Conductance deep level transient spectroscopy (DLTS) and microwave S-parameter measurements have also been made to investigate this behavior. These measurements reveal that surface or channel-substrate interface traps in the material are most likely to be responsible for the observed behavior. A new equivalent-circuit model which accounts for many of the observed characteristics is developed. Unlike previously proposed equivalent circuits, the model does not rely on physically unrealistic circuit element values in order to obtain accurate performance predictions. The bias dependence of circuit element values is computed for one device. Effects not described by the model are also discussed. >