Analysis of current–voltage and capacitance–voltage characteristics of perylene-monoimide/n-Si Schottky contacts

The electrical and interface state properties of Au/perylene-monoimide (PMI)/n-Si Schottky barrier diode have been investigated by current–voltage (I–V) and capacitance–voltage (C–V) measurements at room temperature. A good rectifying behavior was seen from the I–V characteristics. The series resistance (R_s) values were determined from I–V and C–V characteristics and were found to be 160 Ω and 53 Ω, respectively. The barrier height (Φ_b) of Au/PMI/n-Si Schottky diode was found to be 0.694 eV (I–V) and 0.826 eV (C–V). The ideality factor (n) was obtained to be 4.27 from the forward bias I–V characteristics. The energy distribution of interface state density (N_ss) of the PMI-based structure was determined, and the energy values of N_ss were found in the range from E_c ? 0.508 eV to E_c ? 0.569 eV with the exponential growth from midgap toward the bottom of the conduction band. The values of the N_ss without R_s are 2.11 × 10¹² eV^?1 cm^?2 at E_c ? 0.508 eV and 2.00 × 10¹² eV^?1 cm^?2 at E_c ? 0.569 eV. Based on the above results, it is clear that modification of the interfacial potential barrier for metal/n-Si structures has been achieved using a thin interlayer of the perylene-monomide.     

Current–voltage and capacitance–voltage studies of nanocrystalline CdSe/Au Schottky junction interface

Journal of Nanoparticle Research - CdSe nanocrystalline thin films have been synthesized on indium tin oxide (ITO) substrates by an electrodeposition technique. A Schottky junction device in the...     

Capacitance–voltage and conductance–voltage characteristics of Ag/n-CdO/p-Si MIS structure prepared by sol–gel method

The frequency dependent electrical properties of Ag/n-CdO/p-Si structure has been investigated using capacitance–voltage (C–V) and conductance–voltage (G/ω–V) characteristics in the frequency range 10 kHz–1 MHz in the room temperature. The increase in capacitance at lower frequencies is observed as a signature of interface states. The presence of the interfaces states (N_SS) is also evidenced as a peak in the capacitance–frequency characteristics. Furthermore, the voltage and frequency dependence of series resistance were calculated from the C–V and G/ω–V measurements and plotted as functions of voltage and frequency. The distribution profile of R_S–V gives a peak in the depletion region at low frequencies and disappears with increasing frequencies. The values of interface state densities and series resistance from capacitance–voltage-frequency (C–V-f) and conductance–voltage-frequency (G/ω–V-f) measurements were obtained in the ranges of 1.44×10¹⁶–7.59×10¹² cm^?2 eV^?1 and 341.49–8.77 Ω, respectively. The obtained results show that the C–V-f and G/ω–V-f characteristics confirm that the interface states density (N_SS) and series resistance (R_S) of the diode are important parameters that strongly influence the electrical parameters in Ag/n-CdO/p-Si structures.     

Effect of temperature on the current–voltage characteristics of GaAs/AlGaAs quantum cascade photodetectors

Transport of electrons within a quantum cascade photodetector structure takes place with the help of the scattering of electrons by phonons. By calculating scattering rates of the electrons mediated by longitudinal optical phonons (the dominant scattering mechanism), current–voltage characteristic of a quantum cascade photodetector is calculated. The results indicate that with the increase of bias voltage dark current increases rapidly, then the increase becomes slow at higher voltages, whilst photocurrent remains approximately constant with only slight variations in its magnitude. With the increase of temperature from 80 K to 160 K dark current increases by about two orders of magnitude while photocurrent varies slightly, so that at the illuminating power of 1 mW/m² photocurrent density increases in mean from 1.10×10⁻⁹ A/cm² at 80 K to 1.14×10⁻⁹ A/cm² at 160 K and then decreases to 1.03×10⁻⁹ A/cm² at 240 K. Thus the responsivity of the detector varies only slightly with temperature. However owing to the decrease in the resistivity of the photodetector with the increase of temperature, Johnson noise limited detectivity decreases considerably.     

Analytic modelling for current–voltage characteristics of InGaP/InGaAs/GaAs pseudomorphic doped-channel field-effect transistors

A two-dimensional analytic model is proposed for characterizing the InGaP/InGaAs/GaAs metal–insulator–semiconductor (MIS) like pseudomorphic doped-channel field-effect transistor (PDCFET). The velocity overshoot effects, associated with the low effective mass in the In _0.15Ga_0.85 As channel, have been included to solve the 2D Poisson equation. The theoretical simulation provides a convenient and efficient way to describe the device properties of PDCFET’s. The calculated results demonstrate in excellent agreement with the experimental current–voltage characteristics. Device performances with respect to calculations of various structural dimensions have also been extended and investigated.     

Effect of silver doping on the current–voltage characteristic of PbS nanorods

We report on field emission property from a single nanorod measured by using scanning tunnelling spectroscopy. It has been shown that field emission from nanorods of small band gap semiconductor is significantly increasing by doping. The current transport mechanism is explained using double barrier tunnel junction formalism. It is observed experimentally that the Fowler–Nordheim tunnelling mechanism is dominant and governs the transport mechanism. The transport properties of PbS nanostructures in the form of nanorod are investigated in terms of various conduction mechanism. The minimum voltage necessary for triggering Fowler–Nordheim tunnelling under the revised biased for intrinsic sample ~0.95 V and decreases to ~0.67 V for increase doping concentration up to 1.76 wt%.     

Temperature-dependent capacitance–voltage biasing of the highly tunable TlGaTe2 crystals

The temperature effects on the capacitance–voltage characteristics as well as the room temperature capacitance–frequency characteristics of TlGaTe₂ crystals are investigated. A very wide range of linearly varying tunable capacitance from 6.0 μF to 60 pF was recorded. The capacitance–voltage characteristics, being recorded in the temperature range of 290–380 K, revealed a linear increase in the build in voltage associated with exponential decrease in the density of non-compensated ionized carriers with increasing temperature. The high temperature (up to 380 K) biasing ability, the linear tunability and the high dielectric constant values (∼10³) make the TlGaTe₂ crystals applicable in microelectronic components.     

Voltage–current and voltage–flux characteristics of asymmetric high TC DC SQUIDs

We report measurements of transfer functions and flux shifts of 20 on-chip high T_C DC SQUIDs half of which were made purposely geometrically asymmetric. All of these SQUIDs were fabricated using standard high T_C thin-film technology and they were single layer ones, having 140 nm thickness of YBa₂Cu₃O_7?x film deposited by laser ablation onto MgO bicrystal substrates with 24° misorientation angle. For every SQUID the parameters of its intrinsic asymmetry, i.e., the density of critical current and resistivity of every junction, were measured directly and independently. We showed that the main reason for the on-chip spreading of SQUIDs’ voltage–current and voltage–flux characteristics was the intrinsic asymmetry. We found that for SQUIDs with a relative large inductance (L > 120 pH) both the voltage modulation and the transfer function were not very sensitive to the junctions asymmetry, whereas SQUIDs with smaller inductance (L ? 65–75 pH) were more sensitive. The results obtained in the paper are important for the implementation in the sensitive instruments based on high T_C SQUID arrays and gratings.     

Effect of relative humidity on current–voltage characteristics of an electrostatic precipitator

This paper aims at characterizing the behavior of dc corona discharge in wire-to-plane electrostatic precipitators (ESPs) as influenced by the relative humidity (RH) of the inlet air. The current–voltage characteristics and time evolution of the current are analyzed. Experimental results show that discharge current is strongly affected by the RH level of the inlet air. For instance, the time-averaged current is lower at higher RH for a given voltage, except when RH = 99%. Time evolution of the discharge current is affected by the humidity especially in the case of negative corona.     

Influence of interface states on the temperature dependence and current–voltage characteristics of Ni/p-InP Schottky diodes

The ideality factor n$n$ and the barrier height _Φap${\Phi }_{ap}$ of the sputtered Ni/p-InP Schottky diodes have been calculated from their experimental Current–voltage (I–V)$\left(I\text{–}V\right)$ characteristics in the temperature range of 60–400 K with steps of 10 K. The n$n$ and _Φap${\Phi }_{ap}$ values for the device have been obtained as 1.27 and 0.87 eV at 300 K and 1.13 and 0.91 eV at 400 K, respectively. The n$n$ values larger than unity at high temperatures indicate the presence of a thin native oxide layer at the semiconductor/metal interface. The barrier height (BH) has been assumed to be bias dependent due to the presence of an interfacial layer and interface states located at the interfacial layer-semiconductor interface. Interfacial layer-thermionic emission current mechanism has been fitted to experimental I–V$I\text{–}V$ data by considering the bias-dependence of the BH at each temperature. The best fitting values of the series resistance _Rs$R_s$ and interface state density _Ns$N_s$ together with the bias-dependence of the BH have been used at each temperature, and the _Rs$R_s$ and _Ns$N_s$ versus temperature plots have been drawn. It has been seen that the experimental and theoretical forward bias I–V$I\text{–}V$ data are in excellent agreement with each other in the temperature range of 60–400 K. It has been seen that the _Rs$R_s$ and _Ns$N_s$ values increase with a decrease in temperature, confirming the results in the literature.     

Parameter determination from current–voltage characteristics of HgCdTe photodiodes in forward bias region

Current–voltage characteristics of HgCdTe photodiodes in the forward bias region have been modeled considering mechanisms including drift-diffusion current, recombination current, metal-semiconductor contact and constant series resistance. Moreover, a fitting method based on the genetic algorithm has been developed to obtain values of related physical parameters from the measured dynamic resistance–voltage curves. Fitting results of $n^+$ -on- $p$ planar devices with different cutoff wavelengths are presented to illustrate the model and method, which are available and promising in acquiring device parameter values and evaluating the electrode contact quality.     

S-shaped current–voltage characteristics of polymer composite films containing graphene and graphene oxide particles

The resistive switching effects in composite films containing polyfunctional polymers, such as derivatives of carbazole (PVK), fluorene (PFD), and polyvinyl chloride (PVC), and also graphene particles (Gr) and graphene oxide (GO), the concentration of which in the polymer matrices varied in the range from 1 to 3 wt % corresponding to the percolation threshold in such systems, have been studied. The analysis of the elemental composition of the investigated composites by means of X-ray photoelectron spectroscopy have shown that the oxidation degree of Gr in GO is about 9 to 10%. It has been established that a sharp conductivity jump characterized by S-shaped current-voltage curves and the presence of their hysteresis occurs upon applying a voltage pulse to the Au/PVK (PFD; PVC): Gr (GO)/ITO/PET structures, where ITO is indium tin oxide, and PET is poly(ethylene terephthalate), with the switching time, t, in the range from 1 to 30 μs. The observed effects are attributed to the influence of redox reactions taking place on the Gr and GO particles enclosed in the polymer matrix, and the additional influence of thermomechanical properties of the polymer constituent of the matrix.

     

Application of two-mode fiber in voltage sensor

A new mode patter's demodulation technique is put forward. Researches of experiment and theory show that the coupling efficiency of two kinds of different fibers depends on the relative offset between the two fibers when the core diameter of the information pick-up fiber is a little smaller than the major semi-axes of the elliptical-core two-mode fiber. Especially, when the relative offsetδ≈1, fusing splice coupling efficiency reaches peak value. Furthermore, based on the new demodulation scheme, the sine voltage signal applied on the piezoelectric lead zirconate titanate (PZT) is obtained and the detection precision of the system is within±0.2% when the voltage changes between 0.1 and 20 V.     

The current–voltage characteristic in an ultrasmall junction

The current–voltage characteristics of ultrasmall superconductor–insulator–normal metal (S–I–N), and a superconductor–insulator–superconductor (S–I–S) junctions are computed in the presence of a dissipative transmission line. The amplitude of the discontinuous jump at the energy gap of a single-particle current is greatly influenced by the size of the capacitance and the impedance of the external transmission line in the small junction. The results agree with Ambegaokar–Baratoff in the limit of vanishing impedance of a transmission line or large junction capacitance.     

Effect of relative humidity on current–voltage characteristics of monopolar DC wire-to-plane system

This paper deals with the DC monopolar corona discharge in wire-to-plane geometry under variable humid air conditions. The classical formulas of Townsend commonly used for the current–voltage characteristics were used to determine the various corona parameters for the both polarities of the corona discharge. A circular biased probe has been adapted to the plane and is used to measure the ground plane current density and electric field during the monopolar corona discharge. A new approach to the problem of corona discharge in transmission system has been described in this paper. The effect of varying the humidity and wires diameter is also investigated. The values of the electric field and the current density are maximum beneath the corona wire and decrease when moving away from them and the current–voltage characteristics follow the quadratic Townsend's law. The experimental results show that the monopolar corona discharge is strongly affected by the air humidity. The current density and the electric field are measured and compared with the computed values. The agreement between the calculated values and those obtained experimentally is satisfactory. The per unit electric field and current density are also represented by a unique function.     

Emitting layer analysis of blue thermally activated delayed fluorescence devices using capacitance–voltage method

In this paper, blue thermally activated delayed fluorescence (TADF) organic light-emitting diodes (OLEDs) have been elucidated, with a focus on the degradation characteristics of the emission layer (EML). The operational stability against electrical stress was investigated for two host materials and four doping concentrations, which were used as the EML. The operating stability of the devices was confirmed by comparing the peak capacitance before and after degradation. Devices using bis [2-(diphenyl-phosphino) phenyl] ether oxide (DPEPO) as a host exhibited poor degradation characteristics. However, high stability was confirmed when 3,3-di (9H-carba-zol-9-yl)-biphenyl (mCBP) was used. DPEPO host devices are most resistant against performance degradation when they are doped with 10 wt% 10,10'-(4,4′-sulfonylbis(4,1-phenylene))bis(9,9-dimethyl-9,10-dihydroacridine (DMAC-DPS). We successfully determined the electroluminescence characteristics of the device depending on the host material, as well as the doping concentration, using the capacitance–voltage method.