Neutron irradiation effects on I–V characteristics of Au/n-GaAs Schottky diodes

Diodes are one of the most important and widely used components of electronic circuits. These devices can be damaged especially when they are used in radiation fields whose effects depend on radiation type and energy. To investigate these effects, the Au/n-GaAs type Schottky diodes have been irradiated by neutrons emitted from a ²⁵²Cf source which provides neutrons at an average energy of 2.14 MeV. The diode parameters barrier height (Φ_b0), ideality factor (n) and series resistance (R_s) have been obtained from forward current–voltage (I–V) characteristics before and after irradiation and the results are discussed.     

I–V characteristics of vanadium-flavonoid complexes based Schottky diodes

In this study, we have investigated the current–voltage characteristics of the Schottky diodes of two vanadium complexes, VO₂(3-fl) (1) (3-fl=3-hydroxyflavone) and VO(acac)₂ (2), (acac=acetylacetonate), and their composites with TiO₂. Thin films of vanadium complexes and their composites were deposited by the centrifugation method. Current–voltage characteristics of the samples were processed by the modified Shockley equation, Cheung functions and space-charge limited currents (SCLC) approaches. Different junction parameters, such as series resistances, reverse saturation currents, ideality factors and barrier height of the samples, were determined.     

Two diodes model and illumination effect on the forward and reverse bias I–V and C–V characteristics of Au/PVA (Bi-doped)/n-Si photodiode at room temperature

The forward and reverse bias current–voltage (I–V), capacitance/conductance–voltage (C/G–V) characteristics of the fabricated Au/PVA (Bi-doped)/n-Si photodiode have been investigated both in dark and under 250 W illumination intensity at room temperature. The energy density distribution profile of N_ss was extracted from the forward bias I–V measurements by taking the voltage dependence of effective barrier height (Φ_e) and R_s for photodiode both in dark and under 250 W illumination cases. The exponential growth of the N_ss from midgap toward the bottom of the conductance band is very apparent for two cases. The obtained high value of n and R_s were attributed to the particular distribution of N_ss at metal/PVA interface, surface and fabrication processes, barrier inhomogeneity of interfacial polymer layer and the form of barrier height at M/S interface. While the values of C and G/w increase R_s and R_sh decrease under illumination, due to the illumination induced electron–hole pairs in depletion region. The voltage dependent N_ss profile was also obtained from the dark and illumination capacitance at 1 MHz and these values of N_ss are in good agreement. In addition, the fill factor (FF) under 250 W illumination level was found as 28.5% and this value of FF may be accepted sufficiently high. Thus, the fabricated Au/PVA (Bi-doped)/n-Si structures are more sensitive to light, proposing them as a good candidate as a photodiode or capacitance sensor for optoelectronic applications in modern electronic industry.     

The effect of series resistance and interface states on the frequency dependent C–V and G/w–V characteristics of Al/perylene/p-Si MPS type Schottky barrier diodes

The capacitance–voltage–frequency (C–V–f) and conductance–voltage–frequency (G/w–V–f) characteristics of Al/perylene/p-Si Schottky barrier diodes (SBDs) fabricated with spin coating system have been investigated in the frequency range of 30 kHz–2 MHz at room temperature. In order to elucidate the electrical characteristics of SBDs with perylene interface, the voltage and frequency dependent series resistance (R_s), frequency dependent density distribution profile of interface state (N_ss) were obtained. The measurements of C and G/w were found to be strongly dependent on bias voltage and frequency for Al/perylene/p-Si SBDs. For each frequency, the R_s–V plot gives a peak, decreasing with increasing frequencies. Also, it has been shown that the interface states density exponentially decreases with increasing frequency. The C–V–f and G/w–V–f characteristics confirm that the N_ss and R_s of the diode are important parameters that strongly influence the electric parameters in metal/polymer/semiconductor (MPS) structure.     

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.     

Temperature-Dependent Current–Voltage (I–V) and Capacitance–Voltage (C–V) Characteristics of Ni/Cu/n-InP Schottky Barrier Diodes

The current-voltage (I–V) and capacitance-voltage (C–V) characteristics of Ni/Cu/n-InP Schottky barrier diodes are studied over a wide temperature range, from 210 K to 420 K. The I–V characteristics display anomalous thermal behavior. The apparent barrier height decays, and the ideality factor grows at low temperatures, and the series resistances resulting from Cheung’s and Norde’s procedures are markedly temperature dependent. The nonlinearity of the Richardson plot and the strong temperature dependence of the Schottky-barrier parameters indicate that the interface is spatially inhomogeneous. Plots of the zero-bias barrier height as a function of 1/(2kT) points to a Gaussian distribution of barrier heights with 0.90 eV mean height and 0.014 eV standard deviation. When this distribution is accounted for, a Richardson of 6.5 A/(cm K)² results, relatively close to the 9.4/(cm K)² predicted by theory. We conclude that, combined with a Gaussian distribution of barrier heights, the thermionic-emission mechanism explains the temperature-dependent I–V and C–V characteristics of the studied Schottky-barrier diodes.     

Double threshold behaviour of I－V characteristics of CoSi2/Si Schottky contacts

The forward current－voltage (I－V) characteristics of polycrystalline CoSi₂/n-Si(100) Schottky contacts have been measured in a wide temperature range. At low temperatures (≤200K), a plateau-like section is observed in the I－V characteristics around 10^-4A·cm^-2. The current in the small bias region significantly exceeds that expected by the model based on thermionic emission (TE) and a Gaussian distribution of Schottky barrier height (SBH). Such a double threshold behaviour can be explained by the barrier height inhomogeneity, i.e. at low temperatures the current through some patches with low SBH dominates at small bias region. With increasing bias voltage, the Ohmic effect becomes important and the current through the whole junction area exceeds the patch current, thus resulting in a plateau-like section in the I－V curves at moderate bias. For the polycrystalline CoSi₂/Si contacts studied in this paper, the apparent ideality factor of the patch current is much larger than that calculated from the TE model taking the pinch-off effect into account. This suggests that the current flowing through these patches is of the tunnelling type, rather than the thermionic emission type. The experimental I－V characteristics can be fitted reasonably well in the whole temperature region using the model based on tunnelling and pinch-off.     

Investigation of current–voltage and capacitance–voltage characteristics of Ag/perylene-monoimide/n-GaAs Schottky diode

Ag/perylene-monoimide(PMI)/n-GaAs Schottky diode was fabricated and the current–voltage (I–V) characteristics at a wide temperature range between 75 and 350 K and also the capacitance–voltage (C–V) characteristics at room temperature for 1 MHz have been analyzed in detail. The measured I–V characteristics exhibit a good rectification behavior at all temperature values. By using standard analysis methods, the ideality factor and the barrier height are deduced from the experimental data and also the variations of these parameters with the temperature are analyzed. In addition, by means of the Cheung and Cheung method, the series resistance and some other electrical properties are calculated for the diode. Finally, capacitance–voltage characteristics of device have been analyzed at the room temperature. From analyzing the capacitance measurements, Schottky barrier height is determined and then compared with the value which calculated from the I–V measurements at room temperature. Also, the concentration of ionized donors, built-in potential and some other parameters of diode are found using C–V characteristics.     

On the effect of boundary conditions on I–V characteristics of HTSC tunnel junctions

The pairing potential distribution over the thickness of superconducting CuO₂ layers in cuprate HTSCs is determined within the Ginzburg–Landau (GL) theory using the microscopic justification of this theory by Gor’kov. It is found that the pairing potential in them is significantly suppressed due to the effect of non-superconducting interlayers, which results in a decrease in the critical temperature of these superconductors. The temperature dependences of the effective energy gap and current–voltage (I–V) characteristic of tunnel junctions of the “break junction” type made of these superconductors are calculated.     

Current–voltage temperature characteristics of Au/n-Ge (1 0 0) Schottky diodes

The variation in electrical characteristics of Au/n-Ge (1 0 0) Schottky contacts have been systematically investigated as a function of temperature using current–voltage (I−V) measurements in the temperature range 140–300 K. The I–V characteristics of the diodes indicate very strong temperature dependence. While the ideality factor n decreases, the zero-bias Schottky barrier height (SBH) (Φ_B) increases with the increasing temperature. The I–V characteristics are analyzed using the thermionic emission (TE) model and the assumption of a Gaussian distribution of the barrier heights due to barrier inhomogeneities at the metal–semiconductor interface. The zero-bias barrier height Φ_B vs. 1/2 kT plot has been used to show the evidence of a Gaussian distribution of barrier heights and values of Φ_B=0.615 eV and standard deviation σ_s0=0.0858 eV for the mean barrier height and zero-bias standard deviation have been obtained from this plot, respectively. The Richardson constant and the mean barrier height from the modified Richardson plot were obtained as 1.37 A cm⁻² K⁻² and 0.639 eV, respectively. This Richardson constant is much smaller than the reported of 50 A cm⁻² K⁻². This may be due to greater inhomogeneities at the interface.     

Effects of ageing on the electrical characteristics of Cd/CdS/n-Si/Au–Sb structure deposited by SILAR method

Cd/CdS/n-Si/Au–Sb structure has been fabricated by the Successive Ionic Layer Adsorption and Reaction (SILAR) method and the influence of the time dependent or ageing on the characteristic parameters are examined. The current–voltage (I–V), capacitance–voltage (C–V) and capacitance–frequency (C–f) characteristics of the structure have been measured immediately, 1, 3, 5, 15, 30, 45, 60, 75, 90, 105, 120, 135, 150 and 165 days after fabrication of the structure. The characteristic parameters of the structure such as barrier height, ideality factor, series resistance are calculated from the I–V measurements and the barrier height, carrier concentration values are calculated from reverse bias C^?2–V measurements at 500 kHz and room temperature. Furthermore, the density distribution and time constant of the interface states have been calculated from the C–f measurements using the Schottky Capacitance Spectroscopy method as a function of ageing time. It has been seen that the changes of characteristic parameters such as barrier height, ideality factor and series resistance of Cd/CdS/n-Si/Au–Sb structure have lightly changed with increasing ageing time. At the same time, the rectifying ratio of the device increases with ageing time. It can be clearly said that the I–V characteristics of device get better with time.     

Comparative study of the electrical properties of Au/n-Si （MS） and Au/Si3N4/n-Si （MIS） Schottky diodes

In this paper,the electrical parameters of Au/n-Si(MS) and Au/Si3N4/n-Si(MIS) Schottky diodes are obtained from the forward bias current-voltage(I-V) and capacitance-voltage(C-V) measurements at room temperature.Experimental results show that the rectifying ratios of the MS and MIS diodes at±5 V are found to be 1.25 × 103 and 1.27 × 104,respectively.The main electrical parameters of the MS and MIS diodes,such as the zero-bias barrier height(ΦBo) and ideality factor(n),are calculated to be 0.51eV(I-V),0.53eV(C-V),and 4.43,and 0.65eV(I-V),0.70eV(C-V),and 3.44,respectively.In addition,the energy density distribution profile of the interface states(Nss) is obtained from the forward bias I-V,and the series resistance(Rs) values for the two diodes are calculated from Cheung's method and Ohm's law.     

Variation with temperature of the I–V characteristics of polyacetylene nanofibres

The current–voltage (I–V) characteristics of individual nanofibres of doped polyacetylene show a dramatic change from very strong nonlinearities for lightly-doped samples at low temperatures, to nearly ohmic behaviour for higher temperatures and doping levels. At low temperatures (below 10–30 K), the I–V characteristics are independent of temperature and follow the expression for Zener-type tunnelling, as predicted for field-induced tunnelling of the conjugated bond system. At higher temperatures, the I–V characteristics deviate from Zener-type behaviour and the current increases with temperature as thermally-assisted conduction mechanisms become important. The I–V characteristics for the most conductive sample are consistent with our calculations of fluctuation-induced tunnelling.     

The effects of high-energy ion irradiations on the I–V characteristics of silicon NPN transistors

The silicon NPN rf power transistors were irradiated with different linear energy transfer (LET) ions such as 50?MeV Li³⁺, 80?MeV C⁶⁺ and 150?MeV Ag¹²⁺ ions in the dose range of 1–100?Mrad. The SRIM simulation was used to understand the energy loss and range of these ions in the transistor structure. The different electrical parameters such as Gummel characteristics, excess base current (ΔI_B), DC current gain (h_FE), displacement damage factor (K) and output characteristics were systematically studied before and after irradiation. The ion irradiation results were compared with ⁶⁰Co-gamma irradiation result in the same dose range. A considerable increase in base current (I_B) and a decrease in h_FE and I_CSat were observed after irradiation. The degradation in the electrical parameters was comparably very high for Ag¹²⁺ ion-irradiated transistor when compared to other ion-irradiated transistors, whereas the degradation in the electrical parameters for Li³⁺ and C⁶⁺ ion-irradiated transistors was comparable with gamma-irradiated transistor. The isochronal annealing study was conducted on the 100?Mrad irradiated transistors up to 500°C to analyze the recovery in different electrical parameters. The h_FE and other electrical parameters of irradiated transistors were almost recovered after 500°C for 50?MeV Li³⁺, 80?MeV C⁶⁺ ion and ⁶⁰Co-gamma-irradiated transistors, whereas for 150?MeV Ag¹²⁺ ion-irradiated transistor, the recovery in electrical characteristics is not complete.     

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.     

Synthesis and characterization of p-GaSe thin films and the analyses of I–V and C–V measurements of p-GaSe/p-Si heterojunction under electron irradiation

Gallium Selenide (GaSe) thin films were grown by the electrochemical deposition (ECD) technique on Indium tin oxide (ITO) and p-Si (100) substrates. The Electron paramagnetic resonance (EPR) spectrum of GaSe thin films’ growth on ITO was recorded at room temperature. According to EPR results, the g value of an EPR signal obtained for GaSe deposited on ITO is 2.0012?±?0.0005. In/GaSe/p-Si heterojunction was irradiated with high-energy (6?MeV) and low-dose (1.53?×?10¹⁰?e^??cm^?2) electrons. The ideality factor of the In/GaSe/p-Si device was calculated as 1.24 and barrier height was determined as 0.82?eV from I–V measurements before irradiation. Acceptor concentration, built-in potential and barrier height of the In/GaSe/p-Si device were also obtained as 0.72?×?10^14?cm^?3, 0.65?eV and 0.97?eV from C–V measurements, respectively. After irradiation, the ideality factor n and barrier height Φ_b values of the In/GaSe/p-Si device were calculated as 1.55 and 0.781?eV, respectively. Acceptor concentration, the built-in potential and barrier height values of the In/GaSe/p-Si device have also shown a decrease after 6?MeV electron irradiation. This change in heterojunction device parameters shows that current transport does not obey thermionic emission, and thus tunneling could be active due to the defects formed by irradiation at the In–GaSe interface.     

Growth of InSe:Mn semiconductor crystals by Bridgman–Stockbarger technique and analysis of electron irradiation effects on Sn/InSe:Mn Schottky diodes

Mn-doped p-InSe semiconductor crystals were grown by Bridgman –Stockbarger technique. The crystals were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and fabricated Sn/InSe:Mn Schottky diodes. The current–voltage (I–V) and capacitance–voltage (C–V) measurements of diodes were investigated to determine the response of devices to electron irradiation with 9?MeV energy and 1.2?×?10¹⁰?e^??cm^?2 dose. After irradiation, the ideality factor and barrier height of the Sn/InSe:Mn Schottky diode were determined as 1.66 and 0.85?eV, respectively. Before irradiation, they were determined as 1.37 and 0.90?eV, respectively. It has been concluded that the radiation with high energy may contribute to form defects at the interface of the Sn/InSe:Mn device.     

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...