Richardson Constant Research Articles

Zn(II)-based 2D coordination polymer bridged by isophthalate and Dipyridylsulphide : Structural characterisation, Schottky diode device and theoretical interpretation

The design of low cost, easy-to-prepare, soft-to-handle and sustainable material-based technology has been growing day-by-day. Coordination polymers (CPs) are such emerging materials those have been instructed as one of the premium resources to serve the electronic industry. In this aspect, we have designed a hetero-bridging Zn(II)-coordination polymer using two different bridging ligands - 4,4′-Dipyridylsulphide (4,4′-DPS) and 5-Nitroisophthalic acid (5-H2NIA), {[Zn(4,4′-DPS)2(5-HNIA)2(H2O)]n} (Zn-CP) and characterize the crystalline compound with Single Crystal X-ray diffraction (SCXRD) technique. The structure demonstrates that Zn-CP consists of two-dimensional (2D) network with distorted trigonal bipyramidal Zn(II) center (ZnN2O3). The self-assembly of 2D network by different non-covalent interactions forms three-dimensional (3D) supramolecular architecture. Hirshfeld surface analysis effectively evaluates the possibilities of non-covalent interactions present in Zn-CP. Density functional theory (DFT) based numerical calculation using crystallographic parameters has estimated the band gap 3.51 eV which implies the semiconducting nature of Zn-CP. This property has been endorsed by the determination of band gap from Tauc's plot (3.71 eV) using UV–Visible absorption data. The electrical conductivity of Zn-CP determined at room temperature is 8.54 x 10–7 S m-1. The DC activation energy of the device is 9.05 × 10–19 eV with the conductivity limit, 4.71 (Ω-m)-1 having Richardson constant, 7.07 × 10–10Am−2K−2and barrier height is 0.87 eV which suggests that the Zn-CP is n-type semiconductor. Thus, the present work may provide a facile pathway for laboratory-to-land application of such energy materials taking into consideration of technological aspect in the highly energy demanding era. Hence, the synthesized Zn-CP may have energy material application in the semiconducting industry.

Modeling of MoS2/Si heterostructure to study charge transfer dynamics

Here, we synthesized a MoS2/Si heterojunction device using a scalable approach involving DC sputtering coupled with sulfurization. The observed current–voltage characteristics unequivocally indicate a rectifying behavior at MoS2/Si heterointerface. To quantitatively assess the carrier dynamics, a comprehensive analysis utilizing thermionic emission and Landauer transport formalism model was employed. The spatial variation in current across the MoS2/Si devices suggests a potential influence of MoS2’s in-plane series resistance. Furthermore, the electrical behavior of the device is found to be temperature-dependent, with higher temperatures resulting in enhanced conductivity attributed to an increase in thermally generated charge carriers. As temperature rises, the Landauer current model observes an increased ratio of density of states to carrier injection rate, along with other temperature-dependent terms. Meanwhile, the thermionic current model maintains a fixed effective value for its material-dependent term, the Richardson constant, irrespective of temperature changes. Therefore, a comparative analysis between thermionic emission and Landauer transport formalism reveals that the conventional thermionic emission model better aligns with experimentally observed leakage current in reverse bias, showcasing a minimal barrier height at the heterojunction. This comprehensive investigation provides valuable insights into the charge transfer mechanisms at the MoS2/Si interface, opening avenues for its potential innovative applications in electronic devices.

Analysis of barrier inhomogeneities in Ti/p–type strained Si0.95Ge0.05 Schottky diodes using reverse current-voltage characteristics

Extracting electrical parameters such as barrier height inhomogeneities (BHi) from the forward bias can be very challenging in metal/semiconductor (M/Sc) contacts characterized by low barrier height and high series resistance. In this work we demonstrate that the reverse bias characteristics can be used as an efficient alternative method to investigate the inhomogeneity of low barrier height in M/Sc contacts. In particular, the BHi in Ti/p-strained Si0.95Ge0.05 Schottky barrier diodes (SBD) has been investigated using reverse current–voltage-temperature (IR-VR-T) characteristics over the temperature range of 100–300 K. The temperature dependence of the measured barrier heights (ΦRBp) using reverse-bias is successfully explained in terms of a thermionic emission (TE) current transport associated with Gaussian distribution of the barrier height due BHi. The mean homogeneous barrier height (Ф‾RBp) and its corresponding standard deviation (σRs) were determined for different reverse voltages. A decrease in Ф‾RBp and an increase in σRs with increasing reverse bias are observed, indicating a large barrier height distribution upon high applied reverse bias. The deduced average zero-field barrier height (ФFBp≈0.59eV) from IR-VR agrees well with the corresponding value determined from the forward characteristics. Moreover, the reverse bias extracted values for Richardson constant A* based on BHi model, are found in fair agreement with the reported theoretical value of 32 A cm−2 K−2 for our p-type strained Si0.95Ge0.05 alloy. Finally, the results obtained on Pd/n-type Si0.90Ge0.10 structure shown in this work fully support the utilization of such reverse bias method.

Bulk ceramics of lanthanum hexaboride with enhanced spectral selectivity and photothermal efficiency for novel hybrid thermal-thermionic solar absorbers

Lanthanum hexaboride (LaB6) single-crystals are known from a long time for their excellent thermionic and field-assisted electron-emitting properties. Recently, multi-crystalline ceramics, which offer several technological advantages over single-crystals, have been studied as well, proving a low work function and Richardson constant, in addition to favorable optical properties for high-temperature solar radiation absorbers. However, to fully disclose to LaB6 ceramics the novel application of a double-function bulk thermionic emitter, enabled by the direct absorption of solar radiation, and, at the same time, thermodynamic solar absorber for Concentrating Solar Power (CSP), their optical properties should be further optimized. The ideal result, consisting in the selective increase of the solar absorptance and decrease of the thermal emittance, thus increasing both the spectral selectivity and the photothermal efficiency of the absorber, has been obtained in this work by realizing Laser-Induced Periodic Surface Structures (LIPSS) on the ceramic surface by means of femtosecond-laser treatments. LIPPS formation has been investigated as a function of the accumulated laser fluence.

Investigating the effects of TiO2 nanoparticles on the barrier inhomogeneity of brilliant-blue fruit dye-base solar cell

This study aims to investigate the effects of titanium dioxide nanoparticles on the barrier inhomogeneity of a brilliant-blue dye-based solar cell. The cell has been prepared by spin-coating technique. The barrier inhomogeneity was characterized by measuring the cell's current-voltage-temperature (I-V-T) characteristics. The results show that the incorporation of TiO2 nanoparticles leads to a significant reduction in the barrier inhomogeneity of the cell, which results from the improvement of charge injection at the junction. This improvement can be attributed to the role of TiO2 nanoparticles in reducing surface defects and improving the charge injection at the interface. Also, we have investigated the change in the Richardson constant. The homogeneous Richardson constant was found to be 81.63 × 10−7 Am−2K−2 for the dye and the value was modified to 22.85 × 10−7 Am−2K−2 by incorporation of nanoparticles. This illustrates that by the doping of nanoparticles modifies barrier inhomogeneity, resulting in enhanced conductivity.

Evaluation of the current transport mechanism depending on the temperature of Schottky structures with Ti:DLC interlayer

This study emphasizes the possible current transport mechanisms (CTMs) of the Schottky structure with Ti:DLC interlayer for a wide temperature interval (80–470 K). In the related temperature interval, the ideality factor (n) and barrier height (ΦBo) values changed from 6.95 to 2.28 and 0.19 to 0.87 eV, respectively. These temperature dependent n and ΦBo values show that the CTM deviates significantly from the standard TE theory and that the barrier at the metal/semiconductor interface is not homogeneous. Additionally, the observed deviation from linearity of the Richardson plot (RP) at low temperatures and obtained very low Richardson constant (A*) at higher temperatures when compared to its theoretical value are other evidence of deviation from TE theory. The observed two separate linear in the ΦBo-e/2kT plot reveal the Double-Gaussian distribution (DGD) corresponding low and moderate temperature intervals. The modified RP based on the GD of the BH gives a closer to the theoretical value of A* . Along with CTM analyses, the structure’s series resistance (RS) was estimated via both Ohm’s law and Cheung functions. Finally, the Card-Rhoderick method was applied to achieve the variations of the interface trap density (Dit) depending on energy for each temperature by considering voltage-dependent n and ΦB.

Investigation of temperature dependant current transport mechanism in Ag/In2O3/p-Si/Al heterojunction

Employing the pulsed laser ablation technique nano-crystalline thin films of Indium oxide (In2O3) are deposited successfully on boron doped silicon substrate. The structural and morphological parameters of the films are investigated by using X-ray diffraction and atomic force microscopic (AFM) spectroscopy, respectively. The deposited films are the crystalline nanostructures with (400) as preferred diffraction peak and grain size of 56.56 nm approximately. The computed roughness (Rq) of In2O3 film is 1.02 nm. The AFM analysis validated the deposition of homogeneous smooth In2O3 films with surface roughness of the order of nanometer. UV–vis spectroscopy was used to study the optical properties of the films. Greater than 80% transparency in visible region was exhibited by the films. The value of the optical band gap was found to be 3.89 eV. The electrical parameters dominating the mechanism of current transport in n-In2O3/p-Si heterojunction were explored by observing the temperature-dependent current–voltage (I–V) properties. In the temperature range of 80–300 K, the ideality factor and barrier height were found to be strongly temperature dependent. It was noticed that with the decrease in temperature there is increase in ideality factor whereas decrease in barrier height which confirm the interfacial imperfections and inhomogeniety in potential barrier height distributions. The temperature dependence of I–V data has revealed the existence of double Gaussian distribution of barrier heights with mean values of 0.85eV and 0.78eV with standard deviation of 0.014 V and 0.012 V respectively. The modified Richardson's plot gives the average barrier height and Richardson's coefficient as 0.86eV and 4.7 × 105 Am−2K−2 in the temperature range 300 K–180 K and 0.77eV and 5.2 × 105 Am−2K−2, respectively in the temperature range 160 K–80 K. The values of Richardson's constants are of the order of known theoretical value of 3.2 × 105 Am−2 K−2.

Electrical Properties of Ga2O3 Schottky Barrier Diodes with and without Mesa Structure

Devices based on wide bandgap (WBG) semiconductors like silicon carbide (SiC), gallium nitride (GaN), and gallium oxide (Ga2O3) are ideal for high-power electronics in harsh environments. Among the WBG semiconductors, ultrawide bandgap (UWBG) β-phase gallium oxide (Ga2O3), EG ≈ 4.8 eV, is emerging as a replacement for the current commercially available wide bandgap (WBG) power electronics due to its generational improvements in performance and manufacturing cost [1]. Ga2O3 has a high theoretical breakdown electrical field of 8 MV/cm which in turn gives its Baliga’s figure of merit for power devices that is larger than other WBG materials. The availability of high-quality Ga2O3 substrates produced from melt-grown bulk single crystals also facilitates the development of vertical power devices.In the current stage, the vertical Schottky barrier diode (SBD) with Ga2O3 can have an improved current spreading effect when compared to power diode devices from Si, SiC, and GaN. Especially, the Ga2O3 is expected to surpass the trade-off relationship between breakdown voltage (BV) and on resistance (Ron,sp) that other materials have [2]. Nevertheless, the Ga2O3 vertical SBD still cannot achieve the theoretical breakdown electric field. One of the key topics for WBG semiconductors application is a structure for improved electrical management such as field rings, junction termination extension, and field plates to reduce the leakage current in the reverse bias state.Here, we investigate the characteristics of Ga2O3 SBDs with and without mesa structure in extreme environments at high and low temperature. Conventional and mesa Ga2O3 SBDs were fabricated on the halide vapor phase epitaxy (HVPE) grown β-Ga2O3 (001). A Sn-doped substrate with 61016 cm-3 was used for the HVPE growth. In the SBD with mesa structure, the circular mesa with a diameter of 162 μm and a depth of 500 nm was formed around anode electrodes. The Ti/Au metal stack on the back side of the substrate acted as a cathode and the anode electrode deposited Ni/Au/Pt layers. After the fabrication process, current-voltage (I-V) measurements were performed on the SBDs between -5 V and 1 V. From the results, the values of Ron,sp at 0.7 V are 46.4 Ω•cm2 and 46.2 Ω•cm2 in conventional and mesa SBDs, respectively. And additionally, the leakage current at -5 V is reduced by approximately 44.3% in the mesa structure. To obtain the Schottky barrier height (SBH) from I-V and capacitance-voltage (C-V) measurements, the C-V was observed in the range of -5 V to 0.5 V at 100 kHz. The SBH values from I-V and C-V measurements, the mesa SBDs have 1% - 5% larger SBH compared to the conventional structure, and it could be related to lower leakage current. Moreover, the depletion depths of conventional and mesa SBDs were 52.2 nm and 57.8 nm, respectively, from C-V measurements. For considering the electrical characteristics in extreme temperatures, the I-V measurements of both SBDs structure will be measured between 75 K to 525 K. From an initial low temperature measurement series, we determine a Richardson constant of 49 A/cm2 comparable to what has been reported by other groups. Furthermore, we will extend the study by performing deep-level transient spectroscopy (DLTS) to understand the defect information in Ga2O3.

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.

Temperature-dependent Schottky diode behavior of Ni Schottky contacts to α-Ga2O3 film epitaxially grown on sapphire substrate

We fabricated Ni Schottky contacts on α-Ga2O3 epitaxial layers grown on a c-plane sapphire substrate and explored their current–voltage (I–V) characteristics dependence on temperature spanning over a wide temperature range of 100–425K. The Ni/α-Ga2O3 Schottky diode displayed excellent rectification, exhibiting a high barrier height of 1.39 eV, a low leakage current of the order 10−12 A, and a breakdown voltage of 215 V at room temperature. The reverse leakage current was confined within an order of magnitude over the entire measured temperature range, indicating the thermal stability of the diode. A large ideality factor of 1.20 attained at room temperature clearly indicates the diode behavior deviation from the ideal thermionic emission theory. The I–V characteristics revealed that the barrier height and ideality factor shows strong temperature dependence, indicating the existence of barrier inhomogeneity at the Schottky interface. An analysis of the barrier inhomogeneity using the thermionic emission with the assumption of a Gaussian barrier height distribution implies the prevailing double Gaussian barrier height distribution in the Ni/α-Ga2O3 Schottky diode with a transition at 250 K. The Richardson constant derived from the modified Richardson plot, evaluated by assuming the barrier height Gaussian distribution, was close to the theoretical Richardson constant of α-Ga2O3.

Electrical Behavior of Vertical Pt/Au Schottky Diodes on GaN Homoepitaxy

Schottky barrier diodes on GaN on GaN substrates are fabricated for the purpose of material and technology characterization. The epitaxial layers are grown by MOCVD. I–V measurements as a function of the temperature in the range 80–480 K show ideality factor (n) and barrier height (ϕB) variations not following a thermionic (TE) model. Consequently, barrier height fluctuations are considered. In the temperature range 280–480 K, an average barrier height of 1.31 eV with a relatively large standard deviation (σ) of 0.15 eV is extracted using this model. The n(T) variation is also analyzed in order to extract the field sensibility of 1) the mean barrier height variation (ρ2 = −0.1) and 2) the barrier height standard deviation (ρ3 = −15 mV). The corrected Richardson plot using ϕB and σ values is linear and gives a Richardson constant of 31.5 A cm−2 K−2 close to the theoretical value of 26.4 A cm−2 K−2. For a deeper understanding of ϕB fluctuation origins, micro‐Raman mapping of the epitaxial layers and deep‐level transient spectroscopy (DLTS) are used. μ‐RS mappings show compressive strain for diodes having suffered electrical breakdown. DLTS analysis shows the presence of nine levels whose signatures are extracted and nature discussed.

Effect of titanium-dioxide nanoparticle on Richardson constant and barrier height of tartrazine dye based Schottky device

Recently Fruit Dyes have achieved a significant interest as organic devices because of they are widely available, customizable and biodegradable. But low conductivity is one of the major limitations. Low conductivity is due to low charge injection from the electrodes to the organic layer and the charge injection process is strongly dependent on the injection barrier height at the metal-dye interface. Higher barrier height causes low charge injection. A detailed analysis is needed to reduce the interfacial barrier to get better conductivity. In this work, we have estimated the interfacial barrier height of Indium tin oxide coated glass/Tartrazine dye/Copper based device with and without titanium dioxide nanoparticles. The devices have been prepared with dye and dye-nanoparticles blends by using the spin coating technique. We have measured the steady state dark current–voltage–temperature characteristics in the range of 288 K to 333 K to estimate the Richardson constant and interfacial barrier height. The Richardson constant was found to be modified from 44.35 × 10–3 to 07.34 × 10–3 Am−2 K−2. We also have found that interfacial barrier height is reduced from 0.71 eV to 0.64 eV in the presence of nanoparticles at room temperature. As the temperature increased, the interfacial barrier height increased to 0.72 eV from 0.71 eV and to 0.68 eV from 0.62 eV for dye based device with and without nanoparticles, respectively. Reduction of the interfacial barrier height indicates an increase in the charge injection through the interface. This work will be informative to improve the charge flow at the metal–fruit dye interface.

Richardson constant and characteristics of pentacene organic planar Schottky diode

Planar organic Schottky diodes were fabricated using undoped pentacene as an active layer with both palladium and aluminum as contacts. Pentacene organic thin films were deposited on n-type silicon substrates with 100 (n-Si<100>) and 111 (n-Si<111>) orientations. X-ray diffraction (XRD) measurements revealed that the pentacene films’ XRD patterns exhibit several peaks with various orientations. The energy-dispersive X-ray technique was used for chemical analysis of the pentacene, and scanning electron microscopy was used to characterize the surface morphology. A structural and morphological study of the deposited pentacene indicates a polycrystalline triclinic (anorthic) nature. A current–voltage curve was experimentally constructed at temperatures (T) ranging from 300 K to 360 K with a step of 15 K. The diode parameters, such as saturation current, ideality factor (n), and barrier height (ΦB), were systematically analyzed using thermionic emission theory. The fabricated devices exhibit decreasing n and increasing ΦB values with increasing T. Richardson's constant for pentacene was calculated, which indicated that the conventionally calculated value from the temperature-dependent characteristic curve is much lower than the calculated theoretical value. It was also observed that the device deposited over the n-Si<111> substrate exhibited larger forward and lower reverse currents than the n-Si<100> substrate device.

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.

Effect of the contact area on the electrical characteristics of the Ti/6H–SiC (n) Schottky diode

In this paper, we investigated three different sizes (1.6 × 1.6, 1.6 × 0.4 and 0.4 × 0.4 mm2) of Ti Schottky diodes on n-type 6H–SiC epitaxial layers using current-voltage-temperature I–V-T measurements. At room temperature, Schottky contacts I–V characteristics are influenced by the dimensions of the contact area, the bigger and medium diodes present near-ideal behavior following the thermionic emission current theory. However, the characteristics of the smaller diode are affected by the presence of two barrier heights, which can be identified as abnormal interface inhomogeneities. The basic Schottky diode parameters are extracted by the standard Least Mean Square LMS method, recalculated and explained by the thermionic emission current theory (TE) using the Newton-Raphson method.An exhaustive analysis was carried according to the temperature in a wide range 77–500 K which also shows a deviation from the ideality at lower temperatures, thus suggesting that an inhomogeneous barrier has indeed formed and this for all three contacts.The I–V-T analysis allowed us to evaluate the Richardson constant A* in the Ti/6H–SiC Schottky diode by applying the barrier height inhomogeneities correction with the Gaussian distribution. It was close to the theoretical value.

Fabrication of organic-inorganic hybrid device for optoelectronic applications: Charge carriers dynamics and photoresponse assessment

In this study, we introduce the fabrication of an organic-inorganic hybrid architecture for photodetection applications that is constructed from Ethyl Nile Blue (ENB) and p-type silicon. The optical absorption and emission spectra of the deposited ENB films are investigated yielding high UV–visible absorption features with a broad blue and violet emission band. The developed Ag/ENB/p-Si/Al heterojunction's microelectronic characteristics are assessed under dark conditions and at various temperatures (303−353) K. The variation of the barrier height and ideality factor with temperature are interpreted in detail. Considering the barrier height inhomogeneity, the modified Richardson constant has been estimated and found to be 30 A/cm2 K2. Analysis and discussion have been conducted about the charge carrier dynamics scenario under forward and reverse bias settings. The implemented hybrid device's photoresponse is evaluated at various light intensities (20–100 mW/cm2). In comparison to other organic-inorganic hybrid photodetectors, the manufactured hybrid device demonstrated a promising, stable, and reliable performance. The manufactured photodetector exhibited R, D* , LDR, SNR, and (tr/tf) time at power density 100 mW/cm2 of about 1.85 mA/W, 8.5 × 108 Jones, 55.9 dB, 626, and (69.7 ms/52.6 ms), respectively.

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.

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.

The Barrier's Heights and Its Inhomogeneities on Diamond Silicon Interfaces.

In this work, the electrical parameters of the polycrystalline diamonds’ p-PCD/n-Si heterojunction were investigated using temperature-dependent current–voltage (I-V) characteristics. In the temperature range of 80–280 K, the ideality factor () and energy barrier height (φb) were found to be strongly temperature dependent. The φb increases with temperature rise, while the n value decreases. The observed dependencies are due to imperfections at the interface region of a heterojunction and the non-homogeneous distribution of the potential barrier heights. Values of the φb were calculated from I-V characteristics using the thermionic emission theory (TE). The plot of φb versus 1/2 kT revealed two distinct linear regions with different slopes in temperature regions of 80–170 K and 170–280 K. This indicates the existence of a double Gaussian distribution (DGD) in heterojunctions. Parameters such as mean barrier heights and standard deviations σ were obtained from the plots linearization and read out from intercepts and slopes. They take values = 1.06 eV, σ = 0.43 eV, respectively. The modified Richardson plot is drawn to show the linear behavior in these two temperature ranges, disclosing different values of the effective Richardson constants (A*).

Temperature dependence of electrical characteristics and interface state densities of Au/n-type Si structures with SnS doped PVC interface

In this study, the electrical properties of Au/(SnS doped PVC)/n–Si structures were investigated in detail using current/voltage (IV) data in wide temperature range (80–340 K by 20 K steps). Some of the basic electrical parameters such as ideality factor (n), saturation current (I 0), and barrier height (Φ bo ) were obtained. When these parameters were extracted using thermionic emission (TE) theory, it was found that the value of n decreases whereas Φ bo increases with increasing temperature. This result can be explained by the barrier height (BH) inhomogeneity. The observed two linear regions in the plots of Φ bo –n, Φ bo –(1/2kT)1 and (n −1–1)–(1/2kT) in temperature regions of 80–160 K and 80–340 K form an evidence to the presence of Double Gaussian distribution (DGD). Using the plot of Φ bo –(1/2kT), the values of mean BH () and standard deviation (σ S) were found as 0.486 eV and 66 mV for first region, and 0.984 eV and 139 mV for second region, respectively. Thus, the effective Richardson constant (A*) was obtained using the interception point of the modified Richardson plot for these regions as 7.013 × 10−6 A.K−2cm−2 and 88.12 A.K−2cm−2, respectively. It is clear that A* value for second region is closer to theoretical value (=112 A.K−2cm−2 for n–Si). Finally, the energy dependent profile of the surface-states (Nss) was extracted using Card-Rhoderick method and Nss was found to range from ∼1012 (at 80 K) to 1013 eV−1 cm−2 (at 340 K).