Value Of Richardson Constant Research Articles

Analysis of the Current Transport Characteristics (CTCs) in the Au/n-Si Schottky Diodes (SDs) with Al2O3 Interfacial Layer over Wide Temperature Range

Temperature dependent electrical-parameters and CTCs in Au/Al2O3/n-Si SDs have been analysed between 200 K and 400 K using current/voltage (IV) characteristics. While the value of quality/ideality factor (n) decreases, zero bias potential barrier height (BH, ΦB0) increases with increasing temperature. The value of Richardson constant (A*) and activation energy (Ea) were also derived from the conventional Richardson plot (RP) as 0.567 eV and 7.34 × 10−3 A.cm−2K−2, respectively. This low A* value shows that deviation from standard thermionic-emission (TE) model and to determine whether this situation may be described by Gaussian-distribution (GD) model or not, ΦBo vs n and ΦBo vs q/(2kT) curves were illustrated. The Φ ¯ B value was found as 1.19 eV from the linear ΦB0 vs n plot for ideal case (n = 1). The mean-value of BH ( Φ ¯ B 0 ) and standart deviation (σ s) values were found from the ΦBo vs q/(2kT) curve as 1.130 eV and 0.127 V, respectively. By using value of σ s, RP was modified and then Φ ¯ B 0 and A* values were found as 1.128 eV and 108.88 Acm−2K−2, respectively, and this value of A* very close to its theoretical value (=112 Acm−2K−2). The surface state density (Nss) were also obtained from the forward bias IV data for three-temperatures.

The Double Gaussian Distribution of Inhomogeneous Barrier Heights in Au/NAMA/n-Si Schottky Diodes

In this work, we report the results of temperature dependent barrier properties of Au/NAMA/n-Si Schottky diode in the low temperature range of 80–330 K. The analysis results of according to thermionic emission theory showed that the barrier height decreases, and the ideality factor increases towards low temperatures, depend on the barrier height inhomogeneities. The obtained results show the presence of a double Gaussian distributions with standard deviations (σ 0) of 0.073 V and 0.18 V and mean barrier height () values of 0.595 and 1.427 eV in the change of 80–140 K and 160–330 K, respectively. Moreover, evaluation of the modified Richardson curve, the values of Richardson constant (A*) of 321.805 and 110.935 A K−2 cm−2, and mean barrier height of 0.606 and 1.422 eV were found for the low- and high-temperature regions, respectively. The A* value of 110.935 A K−2 cm−2 is close to the theoretical value of 112 A K−2 cm−2 for n-Si. These results proved that there is barrier inhomogeneity.

Inhomogeneous heterojunction performance of Zr/diamond Schottky diode with Gaussian distribution of barrier heights for high sensitivity temperature sensor

Herein, we demonstrated the fabrication and operation of vertical diamond Schottky barrier diode (SBD) as a high-performance temperature sensor. The current transport mechanism and temperature sensor properties of Zr/p-diamond SBD were comprehensively investigated with operating temperatures up to 448 K. At room temperature, Zr/p-diamond SBD exhibits outstanding performances with a high rectification ratio of 2.28 × 1010, a low specific on-resistance of 0.5 mΩ•cm2, a large Schottky barrier height (SBH) of 1.43 eV, a low ideality factor of 1.77, and an extremely low saturation current of 4.42 × 10−22 A. The enhanced-performance with a higher forward current and a lower reverse leakage current is observed to be across a wide temperature range from 323 to 448 K. Additionally, a significant improvement of rectifying current curve with a highest rectification ratio over 1012 is obtained at 423 K. The SBH increases whereas the ideality factor decreases with temperature increasing, indicating barrier inhomogeneities at Zr/p-diamond interface. The temperature-dependent electrical transport characteristics on spatially inhomogeneous Schottky contacts can be successfully described by potential fluctuations model. The extracted original value of Richardson constant (A*) is 0.0153 A/cm2•K2, which is much lesser than theoretical value of 96 A/cm2•K2. The discrepancy of A* value from theoretical value has been well explained by thermionic emission model with Gaussian distribution of barrier inhomogeneity. The values of mean SBH and A* extracted from modified Richardson plot depending on SBH inhomogeneity are 1.76 eV and 105.51 A/cm2•K2, respectively. With a Gaussian distribution take into account, the A* value is close to the theoretical value, and confirmed the existence of SBH inhomogeneity at Zr/p-diamond interface. Furthermore, for Zr/p-diamond SBD operating as a temperature sensor, the voltage drop across the diode decreases linearly with increasing temperature at a specific forward current level, contributing to a highest sensor sensitivity of 6.8 mV/K. The reported results in this work are among the best to date in diamond SBD temperature sensor. Although not optimized for temperature sensor, the high and thermally stable rectifying barriers make Zr/p-diamond SBD a strong candidates for high-performance diamond rectifying diode and temperature sensor.

The effect of temperature on the electrical characteristics of Ti/n-GaAs Schottky diodes

Schottky diodes still attract researchers as they are used in various device applications. This study provides I–V characteristics of Ti/n-GaAs (80–300 K). Higher barrier height (ΦB0) values were obtained for higher temperatures, whereas the ideality factor exhibited the opposite behavior. This was associated with a barrier inhomogeneity at the Ti/GaAs interface, which has a Gaussian distribution (GD). The mean barrier height values calculated from the modified Richardson and ΦB0 - q/2 kT plots were found to be 0.584 eV and 0.575 eV in the temperature range of 80–160 K. They were found as 1.041 eV and 1.033 eV between 180 K and 300 K, respectively. The modified Richardson constant value, on the other hand, was calculated as 22.06 A cm−2 K−2 (80–160 K) and 13.167 A cm−2 K−2 (180–300 K). These values are higher than the theoretical value for n-GaAs, which is 8.16 A cm−2 K−2. This difference may stem from intense inhomogeneity at the Ti/n-GaAs interface.

Findings of inhomogeneity in barrier height of Schottky junction Al/rGO-SnO2 having anomaly in theoretical and experimental value of Richardson constant: A Gaussian approach

In this research, the temperature dependent dynamical behavior of Schottky junction Al/rGO-SnO2 has been investigated with thermionic emission (TE) theory within the temperature regime 303 K to 423 K at interval 20 K. During analysis of electrical charge transport behavior an anomalous change is observed in the value of ideality factor and barrier height with rising temperature for the junction. Experimentally derived Richardson constant (of the order 10-5A/m2K2) using TE theory is exceptionally substandard to the theoretical (of the order 106A/m2K2) values. The beauty of this work is to find out the underline physics for this discrepancy in measurement of Richardson constant (might arose due to inhomogeneity in barrier of metal-semiconductor junction) by assuming the Gaussian distribution of the barrier height with TE theory at the junction. It is obvious that the occurrence of barrier inhomogeneity across the junction leading charge transport phenomena which mostly impacting upon the parameters of Schottky diodes and its nature because of intrinsic formation of ripples and ridges. In this study, it is found that the charge transport mechanism is highly follows the single Gaussian distribution. The material characterization and its Schottky behavior in normal temperature had been published elsewhere.

Analysis of temperature dependent current-voltage characteristics of Sn/p-GaTe/In Schottky diode

In present study, Sn/p-GaTe/In Schottky diode is fabricated using thermal evaporation method. The current–voltage (I–V) measurements of Sn/p-GaTe/In diode are carried out in the temperature range of 40–300 K with the steps of 10 K under dark conditions. While the ideality factor takes values between 1.03 and 1.24 at 300–180 K temperature range, it has values between 1.30 and 5.18 at 170–40 K temperature range. It is observed that the values of ideality factor and series resistance (RS) decrease with increasing temperature. The barrier height increases due to barrier inhomogeneity with increasing temperature since the current prefers to flow through the lowest barrier height with decreasing temperature. The temperature dependence of the inhomogeneous barrier height exhibites a double-Gaussian distribution. The mean barrier height and standard deviation values calculated from the barrier height versus 1/2 kT curve are 0.68 eV and 88.9 meV for the distribution-1 (D1) and 0.36 eV and 42.2 meV for the distribution-2 (D2), respectively. The Richardson constant (A*) value is calculated to be 41.7 for D1 and 55.0 A/K2cm2 for D2 from modified Richardson plot, respectively. These values are very close to the theoretical value of 55.8 A/K2cm2 for the p-GaTe semiconductor.

Evaluation of Richardson Constant of Fruit dyes using Carmoisine and Tartrazine

One of the most crucial variables to consider while analysing the current conduction process in the metal organic Schottky contact is the Richardson constant. However, there aren't many publications on the determination of the useful Richardson constant for Fruit dyes. For two different Fruit dyes, Carmoisine, and Tartrazine, we have determined the values of the effective Richardson constant in this work. By using the spin coating method, a thin organic layer of these natural colours was sandwiched between a copper plate and a piece of glass that had been coated in indium tin oxide. The current-voltage-temperature response of the cells was examined at a temperature range of 303K to 333K. The estimated effective Richardson constants for these dyes are 95.09 x 10-3 A/cm2K2 and 44.35 x 10-3 A/cm2K2 for CS and TZ dye respectively, which are different from the typical value of 120 A/cm2K2. We can analyse several electrical properties for these natural dyes with the aid of these values.

On the examination of temperature-dependent possible current-conduction mechanisms of Au/(nanocarbon-PVP)/n-Si Schottky barrier diodes in wide range of voltage

Au/(nanocarbon-PVP)/n-Si SDs were fabricated and their current-conduction mechanisms (CCMs) have been examined in elaborative by utilizing current–voltage (I–V) characteristics in a temperature range of 60-340 K at (± 3 V) ranges. The values of ideality factor (n) and zero-bias barrier height (ΦB0) determined from the linear-part of semi-logarithmic forward bias IF–VF properties based on Thermionic-Emission (TE) theory revealed that decrease in ΦB0 and increase in n with decreasing temperature. Additionally, Richardson constant (A*) value was very found close to its theoretical value. The values of ΦB0 and n changed from 0.173 eV to 0.837 eV and 16.60 to 2.85 with increasing temperature from 60 to 340 K. The ΦB0 relationship with temperature is disagreement with the negative temperature coefficient of the bandgap of Si for the ideal diode. The calculated higher value of n at low temperatures was attributed to the inhomogeneities of BH rather than the interlayer, surface-states (Nss), and image-force lowering. With lowing temperatures, CCMs may be governed by tunneling over the lower barriers, via Nss, and generation recombination (GR), as well as TE and hence a complete description of CCM and understanding of the formation BH, remain a compelling problem. Nss-(Ec–Ess) profile was also obtained from IF–VF data for each temperature.

The investigation of current condition mechanism of Al/Y2O3/p-Si Schottky barrier diodes in wide range temperature and illuminate

Yttrium oxide (Y2O3) powder was used as an interface layer between metal (Al) and semiconductor (p-Si). Y2O3 powder was coated with a spin-coating method on the p-Si and the Al/Y2O3/p-Si Schottky Barrier Diodes (SBD) was fabricated. The electrical characteristics of the fabricated SBD were analyzed at various temperatures and compared with each other. While ΦB0 decrease from 0.931 eV to 0.211 eV, n increased from 1.63 to 10.07 with decreasing temperature ranging from 340 K to 60 K. The Richardson constant (A⁎) value obtained experimentally for the Al/Y2O3/p-Si SBD was founded as very close to the theoretical A⁎ value of p-Si. Photoconductivity mechanism (PM) of the Al/Y2O3/p-Si SBD was examined by using the photocurrent and the illuminating intensity at −1 V and it was seen that it had a nonlinear behavior. Additionally, the structural and morphologic properties of pure-Y2O3 were analyzed by using X-Rays Diffraction (XRD), Scanning Electron Microscopy (SEM), and Raman spectroscopy (Raman). The fabricated Al/Y2O3/p-Si SBD can be used as a photodiode application in various electronic and optoelectronic technologies.

Estimation of Richardson Constant for Natural Organic dye Based Cells using Orange-lemon and Apple-green

The Richardson constant is one of the most important parameters to analyze the current conduction process in the metal organic Schottky contact. But there are very few reports available on the estimation of effective Richardson constant for the natural dyes. In this work, we have estimated the values of effective Richardson constant for two different natural dyes namely Orange-Lemon and Apple-Green. A thin organic film of these herbal dyes was sandwiched in between Indium Tin Oxide-coated glass and a Copper plate by spin coating technique. The current-voltage-temperature response of the cells was investigated at a temperature interval of 303K to 333K using Keithley 2400 source meter. The effective Richardson constants for these dyes have been estimated which are 110 x 10-3 A/cm2K2, and 118 x 10-3 A/cm2K2 for OL and AG dye respectively, which is different from the conventional value of 120 A/cm2K2. These values will help us to study different electrical parameters for these natural dyes.

Determining the potential barrier presented by the interfacial layer from the temperature induced I–V characteristics in Al/p-Si Structure with native oxide layer

The temperature induced current-voltage (I–V-T) characteristics of the Al/SiO2/p-Si diodes with the interfacial native oxide layer were experimentally investigated in present our study. The values of 24.35 and 1.02 eV for the tunneling factor (aδχ) and the potential barrier presented by the interfacial layer (χ) were determined for the Al/SiO2/p-Si metal-insulator-semiconductor (MIS) diode. The χ value obtained from the forward bias I–V-T characteristics of the SiO2/p-Si diode is a crucial result according to those from only room temperature I–V curves in literature studies. Furthermore, the temperature dependence of the apparent barrier heights of the forward bias I–V-T characteristics displayed a Gaussian distribution (GD) of inhomogeneous barrier heights (BHs). Thus, the standard deviation values of σ1s0=147.65 mV for high temperature range and σ2s0=83.66 mV for low temperature range were obtained from the GD plot of the BHs (the apparent BH versus (2kT)−1 plot). Again, for the mean barrier height Φ‾b0 from the GD plot of the BHs, the values of 1.16 eV and 0.70 eV were obtained from the high temperature region and low temperature region, respectively. Furthermore, the Richardson constant values of 54.66 and 58.42 A/K2cm2 from these temperature regions are approximately 1.70 times higher than the theoretical value of 32 A/K2cm2 of the p-type Si semiconductor.

A Highly Sensitive Temperature Sensor Based on Au/Graphene-PVP/n-Si Type Schottky Diodes and the Possible Conduction Mechanisms in the Wide Range Temperatures

We report that the sensitive temperature response and possible Conduction Mechanisms (CMs) of Au/graphene-PVP/ ${n}$ -Si type Schottky diodes (SDs) are investigated using the standard Thermionic Emission (TE) theory at low temperatures (LTs) and high temperatures (HTs). The obtained results indicate that the zero-apparent barrier height ( $\phi _{\textit {Bo}}$ - $\phi _{\textit {ap}}$ ) increases while the ideality factor ( ${n}$ ), series and shunt resistances ( ${R} _{s}$ , ${R} _{\textit {sh}}$ ), rectifying rate (at ±2V) and surface states ( ${N} _{\textit {ss}}$ ) decrease with increasing temperature. The $\phi _{\textit {Bo}}$ , ${n}$ and ${R} _{s}$ values are also extracted from Cheung’s functions and, then compared with those obtained TE theory. The conventional Richardson plot ( $\ell {n}$ ( ${I} _{o}$ /T 2)- q/kT ) displays the deviation from the linearity at low-temperatures ( $T\le140$ K). Besides, the experimental value of Richardson constant ( ${A} ^{\ast }$ ) deduced from the intercept of plot was found to be several orders lower than the theoretical value. The discrepancies and higher values for the parameter of ${n}$ are important evidences for the deviation from TE theory. This is mainly attributed to the spatial inhomogeneities of the barrier height and potential fluctuations at the interface including low/high barrier areas. Hence the CMs across diode preferentially flows through these lower barriers/patches at the regions of LTs. The decrement in the ${N} _{\textit {ss}}$ with the enhancement in the temperature is in relation to the molecular restructuring-reordering under temperature and voltage effects. The SDs fabricated with graphene-PVP interlayer exhibit a higher sensitivity ( ${S}$ ) rather than many silicon/SOI-based structures. Numerically, the ${S}$ values are found to be in a range of 1.3 mV/K (LTs)/−1.93mV/K (HTs) in case of ${I} =0.1\,\,\mu \text{A}$ as against much greater values of −8.2 mV/K (LTs)/−7.9mV/K (HTs) for ${I} = 10\,\,\mu \text{A}$ .

On the electrical and charge conduction properties of thermally evaporated MoOx on n- and p-type crystalline silicon

In this work, the electrical and charge conduction characteristics of a contact structure featuring thermally evaporated MoOx, deposited on n- and p-type crystalline silicon (c-Si), are extensively investigated by room temperature current–voltage (I–V), transmission line measurements (TLM), and temperature-dependent current–voltage measurements (I–V–T). XRD diffraction spectrum shows that the deposited MoOx film exhibits amorphous nature. From TLM measurements, the values of contact resistivity are calculated to be $${\rho_{\rm {c}}}$$ : 55.9 mΩ-cm2 for Ag/MoOx/n-Si and $${\rho_{\rm {c}}}$$ : 48.7 mΩ-cm2 for Ag/MoOx/p-Si. The barrier parameters such as barrier height ( $${{\phi }_{\mathrm{e}}}$$ ) and ideality factor ( $${n}$$ ) are investigated by the thermionic emission theory for I–V and I–V–T measurements. The $${{\phi }_{\mathrm{e}}}$$ , $${n}$$ , and conventional Richardson plot demonstrate resolute temperature dependency, obeying the barrier height of Gaussian distribution model. The uniform barrier height values are calculated to be $${{\phi }_{\mathrm{b}}}$$ :1.24 eV for Ag/MoOx/n-Si and $${{\phi }_{\mathrm{b}}}$$ :0.66 eV for Ag/MoOx/p-Si from the extrapolation of $${{\phi }_{\mathrm{e}}}$$ at $${n}$$ $${=}$$ 1 of the linear fitting of the variation with the experimental barrier height $${{\phi }_{\mathrm{e}}}$$ with ideality factor. The activation energy ( $${{E}_{\mathrm{a}}}$$ ) and Richardson constant (A*), obtained from Richardson plot, are much smaller than $${{\phi }_{\mathrm{b}}}$$ and the theoretical values of n- and p-type c-Si. The modified Richardson plot yields more reliable Richardson constant and homogeneous barrier height values of 106.2 Acm−2 K−2 and 1.21 eV, 23.4 Acm−2 K−2 and 0.63 eV for Ag/MoOx/n-Si and Ag/MoOx/p-Si heterostructures, respectively. The results demonstrate that thermally evaporated MoOx has particular advantages due to its good rectifying characteristics such as the extra enhancement to barrier height and low contact resistivity for interfacial layer applications.

Temperature dependent Schottky barrier characteristics of Al/n-type Si Schottky barrier diode with Au–Cu phthalocyanine interlayer

The Al/n-type Si Schottky barrier diodes (SBDs) were prepared with Au-Cu phthalocyanine (Au-CuPc) interlayers with different Au and CuPc compositional ratios, probed their temperature dependent current-voltage (I–V) and low frequency noise properties. The Schottky barrier properties like barrier height and the ideality factor are strongly temperature dependent, implying the existence of Schottky barrier inhomogeneities. The barrier inhomogeneities was elucidated using thermionic emission theory based on the assumption of Gaussian distribution of the barrier heights. Further, a divergence in the barrier heights evaluated from the I–V characteristics and Norde's method indicates a deviation of the Al/Au–CuPc/n-type Si SBDs behavior from thermionic emission. The Richardson plot evaluated with the Gaussian distribution of barrier heights method yielded Richardson constant values close to theoretical Richardson constant of n-type Si. The room temperature current noise power spectral density (SI) of the Al/Au–CuPc/n-type Si SBDs having various Au and CuPc concentrations showed a reciprocal of frequency (1/f)γ behavior having γ values near to unity. The decrease in SI and γ with increasing Au concentration in Au-CuPc interlayers was indicative of lessening barrier inhomogeneity. This was also correlated with the decrease in the value of standard deviation derived using temperature dependent I–V characteristics. Further investigations revealed that origins of 1/f noise could be associated with the fluctuations of barrier height and carrier mobility for Al/Au–CuPc/n-type Si SBDs with lower and higher Au compositions in Au-CuPc interlayers, respectively.

The possible current-conduction mechanism in the Au/(CoSO4-PVP)/n-Si junctions

The possible current-conduction mechanism (CCMs) of the Au/CoSO4-PVP/n-Si junctions was investigated using temperature-dependence current–voltage (I–V) experiments over 100–360 K. The experimental results showed that the value of BH increases approximately linearly with increasing temperature. Such positive temperature coefficient (α = ΔΦB0/ΔT) is in agreement with the reported negative temperature coefficient of the bandgap of Si (= − 0.473 meV/K). The (nap−1−1) vs q/2kT curves have different characters in two temperature ranges due to having separate two barrier distributions. The ρ2 and ρ3 values obtained from intercept and slope of these curves as 0.521 V and 0.011 V for 240–360 K temperature range and 0.737 V and 0.004 V for the 100–220 K range. This results show that the high temperature region with smaller ρ2 and larger ρ3 voltage deformation coefficients has a wider and greater of the barrier height distribution than the second region. As an evidence for the Gaussian distribution, the ΦB0 and standard deviation (σ0) were derived from the intercept and slope of the ΦB0-q/2kT curves as 1.14 eV and 0.163 V at high temperatures and 0.62 eV and 0.088 V at low temperatures. The Richardson constant obtained as 102 A/cm2K2 for 240–360 K temperature range using standard deviation value which is similar to the theoretical Richardson constant value of silicon (112 A/cm2K2). For each temperature, the profile of Nss vs (Ec–Ess) was provided using the voltage-dependent effective barrier height (Φe) value. It was observed that these surface conditions decreased with increasing temperature.

Elucidation of Inhomogeneous Heterojunction Performance of Al/Cu5FeS4 Schottky Diode With a Gaussian Distribution of Barrier Heights

Here, we analyze inhomogeneities in the barrier height (BH) of Al/Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> FeS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> Schottky device from the electrical (I-V) measurements with a temperature range between 303 and 408 K. The temperature-dependent performance of our fabricated device is analyzed by using the thermionic emission (TE) theory. Some important diode parameters like BH (Φ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">bo</sub> ), ideality factor (η), and series resistance (R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</sub> ) are evaluated from the forward current-voltage characteristic curves. The calculated η and R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</sub> of the Schottky barrier diode (SBD) decrease, whereas the Φ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">bo</sub> of the device increases with the increase in temperature. The value of Richardson constant (A*) for our material is obtained as 1.94×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-4</sup> 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 the temperature range 303-408 K, which is found as much lesser than the theoretical value of 29.90 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> . The discrepancy of A* from the theoretical value has been well explained by TE theory with the assumption of Gaussian distribution (GD) of BHs due to the existence of BH inhomogeneities at metal semiconductor (MS) junction. The obtained values of the mean BH Φ̅ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">b̅o̅</sub> and the standard deviation σ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</sub> are 1.026 eV and 173 mV in the corresponding temperature range. The mean BH (1.199 eV) and Richardson constant (29.73 Acm <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> ) are determined from the modified Richardson plot depending on the inhomogeneity of BHs. Apparent BH consists of mean BH (Φ̅ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">b̅o̅</sub> ) and standard deviation (σ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</sub> ). The σ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</sub> contributes significantly to the modification of Richardson constant and mean BH. The calculated value of the modified Richardson constant is in close agreement with the theoretical value. From C-V measurements built-in voltage and effective BH of this structure were calculated as a function of frequency.

Hafnium dioxide effect on the electrical properties of M/n-GaN structure

AbstractIn the present paper, using of SILVACO-TCAD numerical simulator for studying the enhancement in Pt/n-GaN Schottky diode current–voltage (I-V) characteristics by introduction of a layer of hafnium dioxide (HfO2) (with a thickness e = 5 nm) between the Pt contact and semiconductor interface of GaN is reported. The simulation of I-V characteristics of Pt/n-GaN was done at a temperature of 300 K. However, the simulation of Pt/HfO2/n-GaN structure was performed in a temperature range of 270 – 390 K at steps of 30 K. The electrical parameters: barrier height (Φb), ideality factor and series resistance have been calculated using different methods: conventional I-V, Norde, Cheung, Chattopadhyay and Mikhelashvili. Statistical analysis showed that the metal-insulator-semiconductor (Pt/HfO2/n-GaN) structure has a barrier height of 0.79 eV which is higher compared with the (Pt/n-GaN) structure (0.56 eV). The parameters of modified Richardson((ln(I0T2)-(q2σs022kT2)=ln(AA*)-q∅B0kT)(\left( {\ln \left( {{{{{\rm{I}}_0}} \over {{{\rm{T}}^{\rm{2}}}}}} \right) - \left( {{{{{\rm{q}}^2}\sigma _{{\rm{s}}0}^2} \over {2{\rm{k}}{{\rm{T}}^2}}}} \right) = \ln \left( {{\rm{AA*}}} \right) - {{{\rm{q}}{\emptyset _{{\rm{B}}0}}} \over {{\rm{kT}}}}} \right)equation versus (1kT{1 \over {{\rm{kT}}}}) have been extracted using the mentioned methods. The following values:ASimul*=22.65 A/cm2⋅K2{\rm{A}}_{{\rm{Simul}}}^* = 22.65\,{\rm{A/c}}{{\rm{m}}^{\rm{2}}} \cdot {{\rm{K}}^2}, 14.29 A/cm2K2, 25.53 A/cm2K2and 21.75 A/cm2K2were found. The Chattopadhyay method occurred the best method for estimation the theoretical values of Richardson constant.

Fabrication and characterization of Au/n-type InP Schottky barrier diode with monolayer graphene interlayer

Au/graphene/n-InP Schottky barrier diode (SBD) was fabricated by the use of spray pyrolysis technique with a monolayer graphene interlayer, and the temperature dependent characteristics was performed in a wide temperature range from 60 to 300 K with steps. The Au/GR/n-InP SBD exhibited excellent rectifying behavior however barrier height (Φb0) of the device increased with increasing temperature while ideality factor (n) and series resistance (Rs) decreased. The strong temperature dependency of SBH and the deviation from theoretical value of Richardson constant clarified by considering a Gaussian distribution model of the SBH which was caused by the BH inhomogeneities. The mean BH of 0.94 and 0.59 eV was estimated with the standard deviation of 0.011 and 0.004 eV attributed to the presence of a double GD of SBD. The modified Richardson plots gave mean BH value of 0.98 and 0.70 eV and the Richardson constant values of 8.10, 13,38 A K−2 cm−2 was very close to its theoretical value of 9.4 A K−2 cm−2. These results yields that carrier transport mechanism of Au/GR/n-InP SBD can be clarified by Thermionic-emission-diffusion (TED) mechanism with a double Gaussian distribution of the SBHs. In addition, the I–V characteristics of SBD under dark and light ambiance indicates that Au/graphene/n-InP is strongly dependent on the light effect. Thus, we can conclude that graphene/n-InP device is a potential candidate for photovoltaic systems. Moreover, the UV–vis spectroscopy of the graphene film exhibit a strong absorption as A = 9.45% compared to the literature, that is, Au/GR/n-InP SBD grown by spray pyrolysis has excellent optical properties for optoelectronic applications.

Analysis of Double Gaussian Distribution at the Interface of Ni/Ta2O5/P-Si Schottky Barrier Diodes Using Temperature Dependent Current-Voltage (I-V) Measurements

The electrical properties have been investigated for Ni/Ta2O5/p-Si Metal/insulator/semiconductor SBD in the temperature regime 175–400 K. The electrical parameters were analyzed using current-voltage characteristics as a function of operating temperature. It is observed that the Schottky barrier height increased whereas ideality factor and series resistance decreased with increasing the operating temperature. The characteristic temperature (To) value calculated from Norde and Cheung methods was compared. This analysis showed that To value extracted from both the techniques are in close agreement with each other. Experimental results revealed that the thermal coefficient was −4.5 mV/K. The Gaussian distribution of the barrier height was estimated from the plot of zero-bias barrier height (Φbo) versus 1/2kT plot and the estimated value of (Φbo) of 0.92 eV and 0.79 eV with standard deviation (σ0) of 0.023 V and 0.014 V, respectively. The mean BH and the Richardson constant values were determined using ln (Io/T2)-q2 $$ {\sigma}_0^2 $$ /2(kT)2 versus 1000/T plot and were 0.89 eV and 0.76 eV and 30.03 and 26.85 A/cm−2 K−2, respectively. In addition to the thermionic emission process, two more conduction mechanisms such as Poole-Frenkel emission in the temperature regime 175–275 K and Schottky emission dominant beyond 300 K temperature were noticed.

Gaussian distribution of inhomogeneous barrier height in nanocrystalline graphite (NCG)/p-Si Schottky diodes

Schottky characteristics of nanocrystalline graphite/p-Si junction were investigated using current–voltage measurements at various temperatures between 298 and 473 K. Using the thermionic emission theory, the extracted ideality factor reduces by 77% while Schottky barrier height increases by 46% with increasing temperature. The initial obtained value of Richardson constant, A* from this device was 7.92 × 10−10 A cm−2 K−2. This value is far smaller than the theoretical value of 32 A cm−2 K−2 for p-Si which indicates inhomogeneity of a barrier height at the device interface. The Gaussian distribution plot was employed to explain the barrier height inhomogeneity, which gives the mean barrier height and standard deviation of 1.23 eV and 0.19 eV, respectively. By including the Gaussian distribution, the analysis of a modified Richardson plot gives a mean barrier height of 1.25 eV and a Richardson constant of 31.09 A cm−2 K−2, which are close to the theoretical values.