Mean Barrier Height Research Articles

Analysis of anomalous transport mechanism across the interface of Ag/p-Si Schottky diode in wide temperature range

We have investigated the detailed temperature dependent mechanism across the interface formed in Ag/p-Si Schottky diode. The Schottky diodes were fabricated by depositing highly pure silver and aluminum metals on the front and back sides of the boron doped p-type semiconductor to form the Schottky and ohmic contacts respectively. The fabricated diode clearly illustrates the rectifying properties between 80 K and 300 K temperature range due to the interface band discontinuity and formation of depleted region. According to thermionic emission diffusion theory the transport mechanisms across the interface reveals abnormal increase in potential barrier and decrease in ideality factor with increase in the temperature due to the potential fluctuations and spatial inhomogeneities at the interface. The inhomogeneities at the interface possess the Gaussian distributions of barrier heights having mean experimental barrier height (ϕ¯b0), 0.91 eV and standard deviation (σ), 0.11 eV respectively. The mean barrier height (ϕ¯b0) of 0.93 eV and Richardson,s coefficient (A∗∗) of 2.7 × 105 Am−2K−2 were obtained from the modified activation energy plot. The Richardson's constant, 2.7 × 105 Am−2K−2 is of the order of known theoretical value of 3.2 × 105 Am−2 K−2 for p-Si. The existence of interface states decreases the capacitance with decrease in the temperature at each applied bias voltage. The higher value obtained for barrier height from CV analysis in comparison to that IV analysis is due the existence of tunneling factor and barrier inhomogeneities. The parameters which characterize the interfacial region were also calculated from CV analysis and found to vary with temperature. The obtained results showed that the fabricated Schottky diode may be a good candidate in the electronic devices.

Temperature dependence of electrical properties in $$\hbox {In/Cu}_{{2}}\hbox {ZnSnTe}_{{4}}\hbox {/Si/Ag diodes}$$ In/Cu 2 ZnSnTe 4 /Si/Ag diodes

\(\hbox {Cu}_{{2}}\hbox {ZnSnTe}_{4}\) (CZTTe) thin films with In metal contact were deposited by thermal evaporation on monocrystalline n-type Si wafers with Ag ohmic contact to investigate the device characteristics of an In/CZTTe/Si/Ag diode. The variation in electrical characteristics of the diode was analysed by carrying out current–voltage (I–V) measurements in the temperature range of 220–360 K. The forward bias I–V behaviour was modelled according to the thermionic emission (TE) theory to obtain main diode parameters. In addition, the experimental data were detailed by taking into account the presence of an interfacial layer and possible dominant current transport mechanisms were studied under analysis of ideality factor, n. Strong effects of temperature were observed on zero-bias barrier height \((\Phi _{\mathrm{B}0} )\) and n values due to barrier height inhomogeneity at the interface. The anomaly observed in the analysis of TE was modelled by Gaussian distribution (GD) of barrier heights with 0.844 eV mean barrier height and 0.132 V standard deviation. According to the Tung’s theoretical approach, a linear correlation between \(\Phi _{\mathrm{B}0} \) and n cannot be satisfied, and thus the modified Richardson plot was used to determine Richardson constant \((A^{*})\). As a result, \(A^{*}\) was calculated approximately as \(120.6\hbox { A cm}^{-2}~\hbox {K}^{-2}\) very close to the theoretical value for n-Si. In addition, the effects of series resistance \((R_{\mathrm{s}} )\) by estimating from Cheng’s function and density of surface states \((N_{\mathrm{ss}} )\) by taking the bias dependence of effective barrier height, were discussed.

Modified approach to modeling barrier inhomogeneity in Schottky diodes

The conventional model describing barrier inhomogeneities in Schottky diodes with a single series resistance leads to many anomalies including crossing over effect in current–voltage–temperature (I–V–T) plots. A new model is therefore proposed here which entails a parallel combination of several diodes, each with its own series resistance. Further, the barrier heights follow a Gaussian distribution function ρ(φ) with a mean barrier height and standard deviation σ. The series resistance is believed to vary inversely with the ρ(φ) value of the concerned barrier height and hence the area occupied. The occurrence of anomalies with the conventional model is examined in depth, and their effective elimination with the proposed model is discussed with the undertaken current simulations. In addition to predicting the increase in apparent barrier height with increase in temperature, decrease in ideality factor with increase in temperature, and elimination of modeling anomalies observed in the conventional model, the model is successful in predicting that apparent barrier height as a function of inverse thermal energy is a quadratic behavior even with a single distribution. This previously required unlikely scenarios involving multiple mean barrier heights and standard deviations with the conventional model. Finally, the description also explains the observed increase in the apparent barrier height with decrease in temperature of a Schottky diode when the values are deduced from the C–V–T data under reverse bias.

Analysis of temperature dependent electrical performance of Al/CuO/ITO Schottky barrier diode and explanation of inhomogeneous barrier heights by double Gaussian distribution

Here temperature dependent electrical properties of two differently synthesized CuO nanoparticles (hydrothermal (CuO (H)) and reflux (CuO (R))) based Schottky barrier diodes (SBDs) have been investigated. Both the materials based devices show an abnormal decrease in the ideality factor (η) and an increase in the barrier height (BH) with the increase in temperature. Experimentally obtained Richardson constant (A*) for both materials based devices show much lower values than the theoretical values. This discrepancy in A* due to the presence of inhomogeneities at the barrier height (BH) of metal-semiconductor (MS) interface has been analyzed by assuming double Gaussian distribution (GD) of the BHs.The mean BH values (ϕb0¯) for CuO (H) based devices obtained as 1.18eV and 1.07eV with standard deviation 0.18V and 0.15 V respectively which are less than the values of its counterpart. The obtained values of A* from the modified plot for both SBDs are in close agreement with the theoretical values. This study portrays a successful explanation of temperature dependent current-voltage characteristics of these two SBDs assuming double GD of the BHs.

Gaussian distribution in current-conduction mechanism of (Ni/Pt) Schottky contacts on wide bandgap AlInGaN quaternary alloy

The current-conduction mechanisms of the as-deposited and annealed at 450 °C (Ni/Pt) Schottky contacts on AlInGaN quaternary alloy have been investigated in the temperature range of 80–320 K. The zero-bias barrier height (BH) (ΦB0) and ideality factor (n) of them were evaluated using thermionic emission (TE) theory. The ΦB0 and n values calculated from the I-V characteristics show a strong temperature dependence. Such behavior of ΦB0 and n is attributed to Schottky barrier inhomogeneities. Therefore, both the ΦB0 vs n and ΦB0 vs q/2kT plots were drawn to obtain evidence on the Gaussian distribution (GD) of the barrier height at the metal/semiconductor interface. These plots show two different linear parts at low and intermediate temperatures for as-deposited and annealed Schottky contacts. Thus, the mean value of ΦB0 and standard deviation (σ0) was calculated from the linear parts of the ΦB0 vs q/kT plots for both samples. The values of the effective Richardson constant (A∗) and mean BH were obtained from the modified Richardson plots which included the effect of barrier inhomogeneity. These values of Richardson constant and barrier height for as-deposited contacts were found to be 19.9 A cm−2 K−2 and 0.59 eV, respectively, at low temperature, but 43.3 A cm−2 K−2 and 1.32 eV, respectively, at intermediate temperatures. These values of Richardson constant and barrier height for annealed contacts were found to be 19.6 A cm−2 K−2 and 0.37 eV, respectively, at low temperature, but 42.9 A cm−2 K−2 and 1.54 eV, respectively, at intermediate temperatures. It is clear that the value of the Richardson constant obtained for as-deposited and annealed samples by using double-GD for intermediate temperatures is close to the theoretical value of AlInGaN (=44.7 A cm−2 K−2). Therefore, I-V-T characteristics for the as-deposited and annealed Schottky contacts in the temperature range of 80–320 K can be successfully explained based on TE theory with double-GD of the BHs.

ZnO Schottky Nanodiodes Processed From Plasma-Enhanced Atomic Layer Deposition at Near Room Temperature

In this paper, we report a low thermal budget manufacturing method to produce highly rectifying Schottky diodes with ultrathin ZnO films grown at near room temperature by plasma-enhanced atomic layer deposition. A bottom Schottky electrode with Pt and a top ohmic electrode with Al/Au stacks were used for metallization. The resultant diodes demonstrated high rectifying ratios on the order of 106, relatively low ideal factor n values of 1.36 ±0.05, effective Schottky barrier height B values of 0.77 ± 0.01 eV, and high breakdown fields of 1.67 MV/cm extrapolated from the current-voltage (I-V) characteristics at room temperature. These specifications are among the best-reported performance of Schottky diodes with ZnO thin films in nanoscale thickness. The interface at the Schottky contacts was investigated and revealed a lateral nonuniform distribution of interface defect states. A modified Richardson plot was used to deduce a mean barrier height (Φ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B0</sub> ) of 1.25 ± 0.1 eV and an apparent Richardson constantc (A**) of 11.64 A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /K <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . In addition, I-V characteristics of the diodes were observed to improve with aging. This newly developed, low thermal budget technique of ZnO Schottky nanodiodes is attractive for hybrid circuit systems and polymer electronics with integration constraints.

Electrical properties of Au–Cu/ZnO/p-Si diode fabricated by atomic layer deposition

The electrical properties of the Au–Cu/ZnO/p-Si diode were investigated with the temperature dependent current–voltage measurements in a wide temperature range from 220 to 360 K with 20 K steps and also frequency dependent capacitance–voltage and conductance–voltage measurements using admittance spectroscopy by changing frequency from 1 to 1000 kHz. The ZnO thin film layer was deposited by atomic layer deposition technique (ALD) to obtain homogenous interface layer and this layer surface was characterized with AFM analyses. Assuming thermionic emission (TE) model, diode parameters such as barrier height and ideality factor were determined for the Au–Cu/ZnO/p-Si diodes and the strong temperature dependence of these values were modeled by TE model with modified by Gaussian distribution of the barrier height. Therefore, the observed non-ideal current behavior was discussed on the basis of barrier inhomogeneity and the presence of native oxide interfacial layer in the diode. The mean barrier height was found as 1.38 eV with 0.18 standard deviation, and the Richardson constant modified by this model was obtained as 28 A/cm2k2 close to the theoretical value. Additionally, the distribution profile of the interface states and series resistance value were evaluated by the capacitance and conductance characteristics. It could be seen from the results that both of them strongly depends on the device frequency. As a result of these works, fabricated Au–Cu/ZnO/p-Si diodes may be used for next technological application in wide range temperature in industry.

Effectuality of Barrier Height Inhomogeneity on the Current–Voltage–Temperature Characteristics of Metal Semiconductor Structures with CdZnO Interlayer

Current-conduction/transport mechanisms (CCMs or CTMs) through barrier and barrier height (BH) formation in the Al/(CdZnO)/p-Si/Al diodes, which were prepared by the sol–gel method, were examined in the range of 110–380 K. The decrease of zero-bias BH (ΦBo) and increase of ideality factor (n) with decreasing temperature were observed. The classic Richardson plot indicated two distinct linear regions that correspond to low and high temperature range (LTR and HTR), respectively. Contrary to this, the acquired Richardson constant value (A*) was much lower than its theoretical value (32 A cm−2 K−2). Such abnormal behavior of the ΦBo, n and A* was attributed to the evidence of the barrier inhomogeneities, especially at low temperature. Therefore, the ΦBo−n, ΦBo and (n−1 − n) versus q/2kT plots were sketched to acquire significant clues for the Gaussian distribution (GD) of the BHs at rectifier contact area with the mean BH ( $$ \bar{\Phi }_{\rm{Bo}} $$ ) and standard deviation (σso), which also have two linear parts with distinct slopes. $$ \bar{\Phi } $$ and σso were calculated from the slope and intercept of ΦBo versus q/2kT plot as 0.802 eV and 0.066 V for LTR, 1.043 eV and 0.106 V for HTR, respectively. The $$ \bar{\Phi }_{\rm{Bo}} $$ and A* were acquired by utilizing the σso values and using the Richardson plot as 0.626 eV and 14.26 A cm−2 K−2 for LTR and 1.021 eV and 32.53 A cm−2 K−2 for HTR, respectively. Thus, the I–V–T characteristics of the Al/(CdZnO)/p-Si/Al diodes at forward biases were successfully elucidated by the double-GD of BHs with mean BHs of 0.626 eV and 1.021 eV, respectively.

Investigation of carrier transport mechanisms in the Cu–Zn–Se based hetero-structure grown by sputtering technique

In this paper, we present results of the electrical characterization of n-Si/p-Cu–Zn–Se hetero-structure. Sputtered film was found in Se-rich behavior with tetragonal polycrystalline nature along with (112) preferred orientation. The band gap energy for direct optical transitions was obtained as 2.65 eV. The results of the conductivity measurements indicated p-type behavior and carrier transport mechanism was modelled according to thermionic emission theory. Detailed electrical characterization of this structure was carried out with the help of temperature-dependent current–voltage measurements in the temperature range of 220–360 K, room temperature, and frequency-dependent capacitance–voltage and conductance-voltage measurements. The anomaly in current–voltage characteristics was related to barrier height inhomogeneity at the interface and modified by the assumption of Gaussian distribution of barrier height, in which mean barrier height and standard deviation at zero bias were found as 2.11 and 0.24 eV, respectively. Moreover, Richardson constant value was determined as 141.95 Acm−2K−2 by means of modified Richardson plot.

The investigation of current-conduction mechanisms (CCMs) in Au/ (0.07Zn-PVA)/n-4H-SiC (MPS) Schottky diodes (SDs) by using (I-V-T) measurements

The semi-logarithmic forward bias I-V plots of the Au/(0.07Zn-PVA)/n-4H-SiC (MPS) type SBDs showed double exponential behavior therefore these plots revealed two distinct linear regions which correspond to low (0.05 V ≤ 0.4 V) and moderate voltage regions (0.4 ≤ V ≤ 0.8 V) (LBR and MBR), respectively, for each temperature level. It was observed that the value of ideality factor (n) decreased with increasing temperature whereas opposite behavior occurred for zero-bias barrier height (ΦB0). The behavior of nkT/q vs kT/q plot for MBR indicated that a combination of thermionic field emission (TFE) and field emission (FE) mechanisms, i.e. the tunneling mechanism, may be dominant especially at low temperatures. In order to explain such unexpected behavior of the conduction mechanism; ΦB0 vs n, ΦB0 vs q/2kT and (n−1 − 1) vs q/2kT plots were drawn to obtain an evidence of a Gaussian distribution (GD) of the barrier heights (BHs) and all of them revealed two linear regions for both LBR and MBR. The conventional Richardson plot was modified by using the obtained standard deviation (σso) of BH from ΦB0 vs q/2kT plots for two bias regions. Thus, the mean BH (Φ̅B0) and effective Richardson constant (A*) values for LBR were calculated from the slope and intercept of the modified Richardson plots as 0.730 eV, 114.12 A cm−2 K−2 at low temperature range (100 ≤ T ≤ 200 K) and 1.304 eV, 97.33 A cm−2 K−2 at high temperature range (200 ≤ T ≤ 320 K), respectively. These values for MBR were found as 0.687 eV, 144.97 A cm−2 K−2 at low temperature range and 1.165 eV, 122.11 A cm−2 K−2 at high temperature range, respectively. It is clear that the values of A* for MBR at low temperatures are closer to 146 A cm−2 K−2 which represents the theoretical value of for n-4H-SiC. As a result, the current conduction mechanisms (CCM) in Au/(0.07Zn-PVA)/n-4H-SiC (MPS) SD can be successfully explained by thermionic emission (TE) mechanism with the double GD of BHs.

Double Gaussian barrier distribution of permalloy (Ni0.8Fe0.2) Schottky contacts to n-type GaN

The temperature-dependent current-voltage (I-V) characteristics of permalloy (Ni0.8Fe0.2) Schottky contacts to n-type GaN have been investigated. Magnetization measurements revealed the ferromagnetic behavior of Ni0.8Fe0.2 film on n-type GaN. The Schottky barrier parameters, such as the barrier height and ideality factor, determined by thermionic emission depended on the measurement temperature, suggesting the presence of lateral inhomogeneity in the Schottky barrier. The experimental data modified by the thermionic emission model along with a Gaussian distribution of the barrier heights indicated the presence of a double Gaussian barrier distribution in the Ni0.8Fe0.2/n-type GaN Schottky contact. The mean barrier heights and standard deviations for each Gaussian distribution were 0.84 & 1.32 eV and 0.10 & 0.17 eV over temperature range of 125–200 K and 225–400 K, respectively. The noise spectral density of the current fluctuations measured as a function of frequency (f) at room temperature followed a 1/fγ dependence with a γ value close to unity, irrespective of the applied forward bias. The 1/f-type noise was attributed to the barrier inhomogeneity existing at the Ni0.8Fe0.2/n-type GaN Schottky interface as revealed from the temperature-dependent I–V characteristics.

Temperature dependent transport characterization of iron on n-type (111) Si0.65Ge0.35 Schottky diodes

Temperature dependent transport characterization of Fe/n-Si0.65Ge0.35 Schottky diodes are investigated using current-voltage measurements between 60 K and 280 K. As temperature is decreased, ideality factor increased and apparent barrier height decreased. Following this trend, charge carriers transport through Metal-Semiconductor (MS) interface changes from Thermionic Emission (TE) to Thermionic Field emission (TFE) over barrier height. In addition, evidence is presented about lateral barrier height inhomogeneity at MS contact. Barrier height ϕB0 vs (1/2 kT) plots show double Gaussian distributions (GD) each with its mean barrier height and standard deviation. Modified Richardson plots obtained using this double GD lead to Richardson constant (A*) and ϕB0 in good agreement with theoretical values for Si1-xGex. Interface states density is also strongly temperature dependent indicating some temperature driven restructuring and reordering taking place at MS interface.

Research on the growth of β-(AlGa)2O3 film and the analysis of electrical characteristics of Ni/Au Schottky contact using Tung's model

Single crystalline β-(AlGa)2O3 epilayer was grown on β-Ga2O3 (010) substrate using pulsed laser deposition. By high resolution X-ray diffraction and X-ray photoelectron spectroscopy measurements, the Al composition was determined to be 11%–13%, somewhat larger than that of target. In addition, Schottky diodes were fabricated on epitaxial β-(Al0.11Ga0.89)2O3 film using Ni/Au as the anode contacts and the electrical characteristics were performed in the temperature range from 300 K to 573 K. From the forward I-V curves, the Φb and n were obtained and they are both strongly dependent on the temperature, which was attributed to the inhomogeneous Schottky barrier height distribution. According to the Tung's model, the mean barrier height of 1.38 eV and A* of 46.52 Acm−2K−2 are extracted by the modified Richardson plot.

A study of temperature dependent current–voltage (I–V–T) characteristics in Ni/sol–gel β-Ga2O3/n-GaN structure

β-Ga2O3 thin films were grown on n-type GaN substrates using the sol–gel method. The forward-biased temperature dependent current–voltage (I–V–T) characteristics of Ni/β-Ga2O3/GaN structure have been investigated in the temperature range of 298–473 K. The apparent barrier height ( $${\phi _{ap}}$$ ) increased while the ideality factor (n) decreased with the increase in temperature. Such a temperature dependent behavior of $${\phi _{ap}}$$ and n was explained by the inhomogeneity of $${\phi _{ap}}$$ , which obeyed Gaussian distribution with zero-bias mean barrier height ( $${\bar {\phi }_{B0}}$$ ) of 1.02 ± 0.02 eV and standard deviation ( $${\sigma _{s0}}$$ ) of 153 ± 0.04 mV. Subsequently, $${\bar {\phi }_{B0}}$$ and Richardson constant A* were obtained from the slope and intercept of the modified Richardson plot as 0.99 ± 0.01 e V and 67.2 A cm−2 K−2, respectively. The $${\bar {\phi }_{B0}}$$ obtained from the modified Richardson plot was in good agreement with the theoretical value calculated from the work function of Ni and electron affinity of β-Ga2O3. The I–V–T characteristics of Ni/β-Ga2O3/GaN MOS structures can be successfully explained by the thermionic emission theory with a single Gaussian distribution of the barrier height.

Analysis of Schottky Barrier Parameters and Current Transport Properties of V/p-Type GaN Schottky Junction at Low Temperatures

The electrical characteristics of a V/p-GaN Schottky junction have been investigated by current–voltage (I–V) and capacitance–voltage (C–V) characteristics under the assumption of the thermionic emission (TE) theory in the temperature range of 120–280 K with steps of 40 K. The zero-bias barrier height (ΦB0), ideality factor (n), flat-band barrier height (ΦBF) and series resistance (RS) values were evaluated and were found to be strongly temperature dependent. The results revealed that the ΦB0 values increase, whereas n, ΦFB and RS values decrease, with increasing temperature. Using the conventional Richardson plot, the mean barrier height (0.39 eV) and Richardson constant (8.10 × 10−10 Acm−2 K−2) were attained. The barrier height inhomogeneities were demonstrated by assuming a Gaussian distribution function. The interface state density (NSS) values were found to decrease with increasing temperature. The reverse leakage current mechanism of the V/p-GaN Schottky junction was found to be governed by Poole–Frenkel emission at all temperatures.

Junction properties analysis of silicon back-to-back Schottky diode with reduced graphene oxide Schottky electrodes

Reduced graphene oxide (rGO)/silicon (Si) Schottky junction possesses promising attributes for various applications such as chemical sensor and photodetector. In this paper, a fabrication of simple back-to-back rGO/Si Schottky junction structure is presented. The device was fabricated via wet processes such as vacuum filtration, patterning by delamination, wet transfer and chemical reduction by ascorbic acid. From the current-voltage measurement, series resistance, barrier height and ideality factor were investigated at different temperature. Barrier height increases and ideality factor decreases with the increase of temperature indicating the inhomogeneity of the junction interface. By considering the Gaussian distribution of barrier height, the fabricated Schottky junction was shown to possess the mean barrier height of 1.24 eV with standard deviation value of 0.16 eV. The obtained mean barrier height was larger than the bandgap of Si, indicating the presence of thin insulation layer at the interface.

An evaluation of structural, optical and electrical characteristics of Ag/ZnO rods/SnO2/In–Ga Schottky diode

ZnO rods were successfully deposited on ZnO seeded SnO2 coated glass substrates by a spray pyrolysis route. It was seen that the grown ZnO sample had a wurtzite structure with a well-defined hexagons of ~ 1–3 µm in diameter. Photoluminescence results measured at 300 K indicated that ZnO rods had a ultra-violet peak located at 383 nm without a deep level band emission. ZnO rods were subsequently used to realize a Ag/ZnO rods/SnO2/In–Ga Schottky diode which displayed rectifying current–voltage (I–V) characteristic with a turn on voltage of 1.2 V at 300 K. Electrical parameters of the Ag/ZnO rods/SnO2/In–Ga Schottky diode were further examined by (I–V) characteristics at the temperature range of 125–300 K with a step of 25 K. Using thermionic emission theory (TET), it was found that the ideality factor reduced with the increase of temperature whereas the zero bias barrier height increased with the increment of the temperature. Using ln(I0)/T2 versus q/nkT plot, Richardson constant (A*) and zero bias barrier height (ΦB0) was obtained as 3.27 × 10−5 A m−2 K−2 and 0.32 eV, respectively. After applying TET with the assumption of Gaussian distribution, a mean barrier height $$(\overline {{{\phi _{B0}}}})$$ and the modified Richardson constant (A**) were determined to be 0.88 eV and 2.75 × 105 A m−2 K−2.

Effect of inhomogeneous Schottky barrier height of SnO2 nanowires device

The current–voltage (I–V) characteristics of metal–semiconductor junction (Au–Ni/SnO2/Au–Ni) Schottky barrier in SnO2 nanowires were investigated over a wide temperature range. By using the Schottky–Mott model, the zero bias barrier height ΦB was estimated from I–V characteristics, and it was found to increase with increasing temperature; on the other hand the ideality factor (n) was found to decrease with increasing temperature. The variation in the Schottky barrier and n was attributed to the spatial inhomogeneity of the Schottky barrier height. The experimental I–V characteristics exhibited a Gaussian distribution having mean barrier heights of 0.30 eV and standard deviation σs of 60 meV. Additionally, the Richardson modified constant was obtained to be 70 A cm−2 K−2, leading to an effective mass of 0.58m0. Consequently, the temperature dependence of I–V characteristics of the SnO2 nanowire devices can be successfully explained on the Schottky–Mott theory framework taking into account a Gaussian distribution of barrier heights.

Temperature-Dependent Electrical Characteristics of Au/Si3N4/4H n-SiC MIS Diode

Electrical characteristics of the Au/Si3N4/4H n-SiC metal–insulator-semiconductor (MIS) diode were investigated under the temperature, $$ T $$ , interval of 160–400 K using current–voltage (I–V), capacitance–voltage ( $$ C {-} V $$ ) and conductance–voltage ( $$ G/\omega {-} V $$ ) measurements. Firstly, the Schottky diode parameters as zero-bias barrier height ( $$ \Phi_{{\rm B}0} $$ ) and ideality factor ( $$ n $$ ) were calculated according to the thermionic emission (TE) from forward bias I–V analysis in the whole working $$ T $$ . Experimental results showed that the values of $$ \Phi_{{\rm B}0} $$ were in increasing behavior with increasing $$ T $$ while $$ n $$ values decreased with inverse proportionality in $$ n $$ versus $$ \Phi_{{{\rm{B}}0}} $$ plot. Therefore, the non-ideal I–V behavior with inhomogeneous barrier height (BH) formation has been discussed under the assumption of Gaussian distribution (GD). From the GD of BHs, the mean BH was found to be about 1.40 eV with 0.1697 standard deviation and the modified Richardson constant $$ A^{*} $$ of this diode was obtained as 141.65 A/cm2 K2 in good agreement with the literature (the theoretical value of $$ A^{*} $$ is 137.21 A/cm2 K2). The relationship between $$ \Phi_{{\rm B}0} $$ and $$ n $$ showed an abnormal I–V behavior depending on $$ T $$ , and it was modeled by TE theory with GD of BH due to the effect in inhomogeneous BH at the interface. Secondly, according to Cheung’s model, series resistance, $$ R_{\rm{S}} $$ values were calculated in the $$ T $$ range of 160–400 K and these values were found to decrease with increasing $$ T $$ . Finally, the density of interface states, $$ D_{\rm{it}} $$ was calculated and the $$ T $$ dependence of energy distribution of $$ D_{\rm{it}} $$ profiles determined the forward $$ I {-} V $$ measurements by taking into account the bias dependence of the effective BH, $$ \Phi_{\rm{e}} $$ and $$ n $$ . $$ D_{\rm{it}} $$ were also calculated according to the Hill–Coleman method from $$ C {-} V $$ and $$ G/\omega {-} V $$ analysis. Furthermore, the variation of $$ D_{\rm{it}} $$ as a function of frequency, $$ f $$ and $$ T $$ were determined.

Modeling of Mean Barrier Height Levying Various Image Forces of Metal–Insulator–Metal Structure to Enhance the Performance of Conductive Filament Based Memristor Model

Memristor manifests resistive switching based memory as its inherent property. Simple nanoscale structure, nonvolatility, low-power operation, and fast computing make it viable to compete with the emerging memory technologies. In this paper, we design the mean barrier height of metal–insulator–metal structure by imposing various image forces on it. Parabolic, triangular, and rectangular nature of image force potentials are superimposed with reported rectangular potential barrier to see their impact in tunneling current. Results revealed that the triangular image force significantly lower the barrier and results in highest current density among other barriers. Parabolic image force shows a 40% improvement in current density at higher voltage range when compared with reported hyperbolic image forces, whereas rectangular image force yield least current. The resultant relations are deployed in the existing conductive filament based memristor model to investigate the pinched hysteresis I – V characteristics. To validate our design approach, we compared the results with reported experimental data of memristor as well as spice model of memristor, which includes hyperbolic image potential. It is inferred that parabolic image potential builds better agreement with reported data as compared to others and shows a maximum off-switching current $1.74\,\times \,10^{- 3}$ A and on-switching current $0.95\times 10^{- 3}\;{\rm{A}}$ . The improved model of memristor can be employed to various applications like neuromorphic computing, logic design, and memory design.