Modified Richardson Constant Research Articles

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.

Integration of biocompatible Coomassie Brilliant Blue dye on silicon in organic/Inorganic heterojunction for photodetection applications

Here, we introduce systematic investigations of structural, morphological, and optical properties of solution-processed coomassie brilliant blue, CBB, thin films for photodetection applications. First, the structural and morphological features of the spin-coated CBB thin films are investigated using XRD and FESEM microscopy and yielded a polycrystalline, nanostructured, and porous CBB film of crystallite size and RMS roughness ∼31.95 nm and 10.65 nm, respectively. The UV–Vis–NIR spectrophotometric measurements of transmittance and reflectance elucidated the efficient absorption and light-harvesting of the UV and visible light range with estimated indirect energy gap and Urbach energy ∼1.54 eV and 22.3 meV, respectively. Next, the dispersion behavior of the fabricated thin films is analyzed in the light of the single-oscillator model estimating the detail dispersion parameters. Furthermore, the dielectric function, as well as the nonlinear optical parameters, is accurately estimated. Subsequently, the microelectronic parameters of the engineered rectifying Ag/CBB/p-Si/Al heterojunction such as ideality factor, barrier height, series, and shunt resistances are estimated at different temperatures. The charges dynamical mechanism and the interface states density profile are analyzed, and the thermionic emission model is confirmed to fit the low bias region with a modified Richardson constant of about 34.8A/cm2K2.After that, the photoresponse of the implemented organic/inorganic heterojunction is checked at different illumination intensities and showed a significant stable sensitivity with fast On-Off switching behavior. The fabricated heterojunction achieved good figures of merit such as responsivity, specific detectivity, linear dynamic range, and rise/fall time of about 4.289 mA/W, 2.07 × 109 Jones, 30.36 dB, and 61.6/82.5 ms, respectively. The good and stable responsive performance of the current Ag/CBB/p-Si/Al architecture may make it a potential candidate for photodetection applications.

Electrical transport properties of thermally stable n-ZnO/AlN/p-Si diode grown using RF sputtering

The temperature dependent electrical transport properties of n-ZnO/AlN/p-Si heterojunction diode fabricated by RF sputtering system have been investigated over a wide temperature range of 303 K–413 K. The AlN buffer layer in-between ZnO and Si lowers the mismatch in thermal expansion coefficient/lattice constant for improved electrical and structural characteristics. XRD pattern and FESEM confirm the crystalline nature and good quality of ZnO thin film with uniform grain size and crack free structure respectively. As measured from the temperature dependent I–V curve, the apparent barrier height reduces as Ideality factor rises which shows good thermal stability within the temperature range studied here. The mean value of barrier height as well as the Richardson constant have been evaluated. Additionally, by taking into account the Gaussian distribution of inhomogeneous barrier heights, the modified Richardson constant has been estimated.

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.

Temperature Effect on Al/p-CuInS2/SnO2(F) Schottky Diodes

In this paper, Schottky diodes (SDs) obtained by evaporated thin films of aluminum on pulverized p-CuInS2/SnO2:F have been studied using J-V-T characteristics in a temperature range of 200-340K. These characteristics show that aluminum acts as a rectifier metal-semiconductor contact. Characteristic variables of the Al/p-CuInS2/SnO2:F junctions, such as the current density, the serial resistance, the parallel conductance, the Schottky barrier height (SBH), and the ideality factor of the SD were obtained by fitting the J-V-T data using the Lambert function. Data analysis was conducted with the use of MATLAB. Results showed that n is greater than 1, which could be explained by the existence of inhomogeneities due to the grain boundaries in CuInS2. Through this analysis, one can see a good agreement between experimental and modeled data. The study has shown that the main contribution in the current conduction in such heterostructures is the thermionic emission (TE) supported by the recombination of the carriers. The last phenomenon appears mainly in the grain boundaries, which contain both intrinsic and extrinsic defects (secondary phases, segregated oxygen). An investigation of the J-V-T characteristics according to TE theory has demonstrated that the current density and the SBH increase while serial resistance, parallel conductance decrease with an increase in temperature. After an SBH inhomogeneity correction, the modified Richardson constant and the mean barrier height were found to be 120AK-2cm-2 and 1.29eV respectively. This kind of behavior has been observed in many metal-semiconductor contacts.

Barrier height inhomogeneities on Pd/n-4H-SiC Schottky diodes in a wide temperature range

Barrier height inhomogeneities on Pd/n-type 4H-SiC Schottky barrier diodes in the 300–800 K temperature range have been investigated. Palladium is known to form silicide above 673 K. Temperature dependent current-voltage (I-V) characteristics were analyzed. Barrier height (BH) and ideality factor (n) were found to be strongly temperature dependent. Barrier height increased, whilst ideality factor decreased with increasing in temperature and the Richardson plot showed some deviation from linearity. This was attributed to barrier inhomogeneities at the metal-semiconductor interface which resulted in a distribution of barrier heights. From the modified Richardson plot, the modified Richardson constant, A** was found to be 155 Acm−2K−2 and 87 Acm-2 K−2 in the 300–525 K and the 550–800 K temperature ranges respectively.

Analysis of barrier inhomogeneities in AuGe/n-Ge Schottky diode

The barrier inhomogeneities in AuGe/n-Ge Schottky diode have been analyzed by using current–voltage (I–V) measurements over a wide temperature range of 200 to 400 K. The electrical parameters such as ideality factor (n), zero-bias barrier height (ΦBo), and series resistance (Rs) of the diode were found to be strongly temperature dependent. The abnormal increase of the barrier height with temperature was attributed to the existence of barrier height inhomogeneities at the metal/semiconductor interface. Therefore, the conventional and modified Richardson plots were drawn to explain Gaussian distribution (GD) of barrier heights. The modified Richardson plot shows a good linearity over the temperature range. The modified Richardson constant (A*) was found to be 141.49 A cm−2 K−2, which is close to the theoretical value of 140 A cm−2 K−2 for n-Ge. Moreover, the barrier height values obtained from I–V and Norde methods are found to be in good agreement with each other.

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.

Transport properties of Gallium Phosphide based Schottky contact with thin insulating layer

The current-voltage (I-V) characteristics of Au/n-GaP Schottky barrier diode was analyzed in wide temperature range of 220–400K. The conduction mechanism in the low bias region, except for 220K and 240K, was identified as tunneling (TN). Nevertheless, thermionic emission (TE) becomes dominant as the voltage increases. The diode parameters were evaluated in this region by TE model incorporating the concept of thin insulating layer. The series resistance (Rs) of the device was found to decrease with increase in temperature. In the 220–320K temperature range, as reported for most of the Schottky diodes, the zero-bias barrier height (ϕb0) decreases and the ideality factor (η) increases with the decrease of temperature. The value of modified Richardson constant (A**) obtained agrees well with the theoretical value. However, in the 320–400K range, the variation of η and ϕb0 with temperature shows opposite trend, which is speculated as due to the change in conduction pattern by the temperature induced modifications at the interface.

Electrical characteristics and rectification performance of wet chemically synthesized vertically aligned n-ZnO nanowire/p-Si heterojunction

Vertically well-aligned n-ZnO nanowire (NW) thin films were deposited onto p-Si substrates by a two-step wet chemical technique to form a p–n heterojunction diode. The morphological and structural characteristics of the ZnO NW performed by scanning electron microscopy (SEM) and x-ray diffraction (XRD) revealed well-aligned h-ZnO NW with a wurtzite structure. A direct optical band gap of 3.30 eV was calculated from the transmittance trace obtained using a UV–VIS–NIR spectrophotometer. The electrical characteristics of the heterojunction diode were studied by capacitance–voltage (C–V) measurement at room temperature, and current–voltage–temperature (I–V–T) measurements performed in the 300–400 K range. The C–V measurements yield a carrier concentration of 1.3 × 1016 c.c.−1 for the ZnO NW thin film. The ideality factor (n) was found to decrease, while the barrier height (φb0) increased with the increase in temperature, when calculated using a thermionic emission model from the non-linear I–V–T plots. The series resistance (Rs) calculated by the Cheung–Cheung method decreased with the increase in temperature. The mean barrier height (0.718 eV) and modified Richardson constant (28.4 A cm−2 K−2) calculated using a Gaussian distribution of barrier heights (considering barrier height inhomogeneity) were closer to the theoretical value than those calculated from the linear approximation of the ln(Is/T2) versus 1000/T plot. The variation of the density of interface states with interface state energy was also studied. The n-ZnO NW/p-Si heterojunction diode performed very good half wave rectification in the frequency range 50 Hz–10 kHz, when a sinusoidal ac voltage of amplitude 4.5 V was applied across it.

Current–voltage and capacitance–voltage characteristics of Al Schottky contacts to strained Si-on-insulator in the wide temperature range

The electrical characteristics of Al/strained Si-on-insulator (sSOI) Schottky diode have been investigated using current–voltage (I–V) and capacitance–voltage (C–V) measurements in the wide temperature range of 200–400K in steps of 25K. It was found that the barrier height (0.57–0.80eV) calculated from the I–V characteristics increased and the ideality factor (1.97–1.28) decreased with increasing temperature. The barrier heights determined from the C–V measurements were higher than those extracted from the I–V measurements, associated with the formation of an inhomogeneous Schottky barrier at the interface. The series resistance estimated from the forward I–V characteristics using Cheung and Norde methods decreased with increasing temperature, implying its strong temperature dependence. The observed variation in barrier height and ideality factor could be attributed to the inhomogeneities in Schottky barrier, explained by assuming Gaussian distribution of barrier heights. The temperature-dependent I–V characteristics showed a double Gaussian distribution with mean barrier heights of 0.83 and 1.19eV and standard deviations of 0.10 and 0.16eV at 200–275 and 300–400K, respectively. From the modified Richardson plot, the modified Richardson constant were calculated to be 21.8 and 29.4Acm−2K−2 at 200–275 and 300–400K, respectively, which were comparable to the theoretical value for p-type sSOI (31.6Acm−2K−2).

Temperature-dependent current–voltage characteristics of Pd/ZnO Schottky barrier diodes and the determination of the Richardson constant

We report on a systematic investigation of temperature dependent current–voltage (I–V) characteristics of Pd/ZnO Schottky barrier diodes in the 30–300K temperature range. The ideality factor was observed to decrease with increase in temperature, whilst the barrier height increases with increase in temperature. The observed trend has been attributed to barrier inhomogeneities, which results in a distribution of barrier heights at the interface. Using the dependence of saturation current values on temperature, we have calculated the Richardson constant (A⁎) which was investigated in the two distinct temperature regions: 140–200K and 210–300K and values of 3×10−12 and 3×10−9Acm−2K−2 were obtained, respectively. A mean barrier height of 0.97eV was obtained in the 140–300K temperature range. Applying the barrier height inhomogeneities correction, the value of A⁎ was obtained from the modified Richardson plots as 39.43 and 39.03Acm−2K−2 in the 140–200K and 210–300K temperature range. The modified Richardson constant (A⁎⁎) has proved to be strongly affected by barrier inhomogeneities and dependent on contact quality.

Study of barrier height and trap centers of Au/n-Hg3In2Te6 Schottky contacts by current-voltage (I-V) characteristics and deep level transient spectroscopy

The temperature-dependent electrical characteristics of the Au/n-Hg3In2Te6 Schottky contact have been studied at the temperature range of 140 K–315 K. Based on the thermionic emission theory, the ideality factor and Schottky barrier height were calculated to decrease and increase from 3.18 to 1.88 and 0.39 eV to 0.5 eV, respectively, when the temperature rose from 140 K to 315 K. This behavior was interpreted by the lateral inhomogeneities of Schottky barrier height at the interface of Au/n-Hg3In2Te6 contact, which was shown by the plot of zero-bias barrier heights Фbo versus q/2kT. Meanwhile, it was found that the Schottky barrier height with a Gaussian distribution was 0.67 eV and the standard deviation σ0 was about 0.092 eV, indicating that the uneven distribution of barrier height at the interface region. In addition, the mean value of Φ¯b0 and modified Richardson constant was determined to be 0.723 eV and 62.8 A/cm2K2 from the slope and intercept of the ln(Io/T2) – (qσ02/2k2T2) versus q/kT plot, respectively. Finally, two electron trap centers were observed at the interface of Au/n-Hg3In2Te6 Schottky contact by means of deep level transient spectroscopy.

Temperature dependent current transport of Pd/ZnO nanowire Schottky diodes

Zinc oxide (ZnO) nanowire based Schottky barrier diodes are fabricated by depositing Pd metal contact on top of vertically well-aligned ZnO nanowire arrays. A vertical array of ZnO nanowires on indium tin oxide (ITO) coated glass substrates is synthesized by hybrid wet chemical route. Scanning electron microscopy (SEM), x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) measurement confirm the formation of stoichiometric well-aligned hexagonal (h-ZnO) nanowire arrays with wurtzite structure. Temperature dependent current–voltage (I–V) measurements on palladium-ZnO (Pd/ZnO) nanowire Schottky junctions in the temperature range 303–383 K exhibit excellent rectifying character. From these nonlinear I–V plots, different electrical parameters of diode-like reverse saturation current, barrier height and ideality factor are determined as a function of temperature assuming pure thermionic emission model. The ideality factor is found to decrease while the barrier height increases with the increase in temperature. The series resistance values calculated from Cheung’s functions also show temperature dependency. Such behavior can be attributed to the presence of defects that traps carriers, and barrier height inhomogeneity at the interface of the barrier junction. After barrier height inhomogeneity correction, considering a Gaussian distributed barrier height fluctuation across the Pd/ZnO interface, the estimated values of mean barrier height and modified Richardson constant are more closely matched to the theoretically predicted value for Pd/ZnO Schottky barrier diodes. The variation of density of interface states as a function of interface state energy is also calculated.

Influence of the nitrogen concentration on the electrical characteristic of hydrogenated amorphous silicon nitride (a-SiN_x:H) based Schottky diodes

In this study, the Schottky diode characteristic of hydrogenated amorphous silicon nitride (a-SiN_x:H) samples containing various amounts of nitrogen have been investigated via both I-V and C-V measurements. From forward bias I-V measurements in the dark, the barrier height of samples (\phi_{B0}), ideality factor (\eta ), modified Richardson constant (A^\ast) and series resistances (R_s) have been obtained as the function of temperature for different nitrogen content. In addition, forward and reverse bias current ratios (I_f/I_r) at V~=~1 volt have been investigated as the function of temperature for different nitrogen content. Light sensitivity of the samples has also been investigated under different light intensities at room temperature. From the C-V measurements in the dark and at room temperatures, the dielectric constant of each samples have been obtained as a function of nitrogen content.

Characterization and modeling of temperature-dependent barrier heights and ideality factors in GaAs Schottky diodes

A semi-analytical model for Schottky diodes with ideality factors ( η) greater than 1.00 is presented with an experimental verification from n-type GaAs Schottky diodes ( η = 1.00–2.47 over T = 83–323 K). Adopting a correcting ideality factor in the distribution function, an accurate modeling of temperature-sensitive variations of current–voltage characteristics and accurate extraction of Schottky barriers are obtained with a modified Richardson constant. Temperature-dependent Schottky barriers ( ϕ bn = 0.928 V∣ 83 K –0.837 V∣ 323 K ), obtained from the semi-analytical model, are consistent with the variation of the energy bandgap with temperature which is known to be the main cause for the change of Schottky barriers.

The influence of ohmic back contacts on the properties of a-Si:H Schottky diodes

We have investigated the temperature dependence of the current–voltage ( I– V) characteristics of Au/a-Si:H Schottky structures using different back metal ohmic contacts (Al, Cr, Mg or combination of Mg/Sb). I– V characteristics were measured in a wide temperature range (from 145 to 425 K) to find out the temperature dependence of the ideality factor, barrier height and series resistance for the different metal contacts used. We have also calculated the modified Richardson constant and barrier height from the plot of thermionic emission saturation current as a function of temperature.

Ruthenium and ruthenium-based contacts to GaAs

This paper deals with the outstanding electrical and structural properties of Ru-based Schottky and ohmic contacts fabricated by electron beam evaporation on n- and p + -type GaAs, respectively. The effective and flatband barrier heights were evaluated by standard current-voltage ( I–V)( T) and capacitance-voltage ( C–V)( T) measurements, over the temperature ( T) range 100 to 350 K. The modified Richardson constant, A ∗∗, varied between 2.2 and 4.9 A cm −2 K -2, depending upon the annealing temperature. AES depth profiles indicated that Ru forms structurally very stable contacts to GaAs, with no evidence from XPS measurements of any compound formation between Ru and GaAs even after annealing up to 500°C. A sharp increase was observed in the formation of Ga 2O 3 at the interface between the Ru layer and the GaAs after vacuum annealings at temperatures of 450°C and above. Only limited diffusion of arsenic through the Ru layer was observed after annealing at 400°C, but increased rapidly above 450°C. A Au/Ru/p +-GaAs ohmic contact system showed comparable specific contact resistance (5.5×10 −6 Ω·cm 2) to those systems commonly used, but with superior surface morphology.

Conduction mechanisms in erbium silicide Schottky diodes

Conduction mechanisms in erbium silicide Schottky diodes on n-type silicon have been studied over a temperature range of 25 to 160 K. Thermionic emission is the dominant carrier transport mechanism above 70 K. Below this temperature, deviations are apparent in the zero-bias barrier height and ideality factor. However, the flat-band barrier height is shown to remain constant over the entire temperature range. The Fermi level is demonstrated to be pinned to the conduction band. A new quantity, the flat-band saturation current (Isf) is defined. Plots of n ln(Isf/T2) vs 1/T are found to give an excellent fit to the data over 28 orders of magnitude. From these plots the flat-band barrier height and the modified Richardson constant are obtained directly. This technique provides a completely self-consistent and more reliable way of obtaining these parameters than do previous methods. For low temperatures and low forward bias, recombination via tunneling through surface states becomes the dominant conduction mechanism.

Analysis of I– V measurements on PtSi-Si Schottky structures in a wide temperature range

I– V Measurements on PtSi-Si Schottky structures in a wide temperature range from 90 to 350 K were carried out. The contributions of thermionic-emission current and various other current-transport mechanisms were assumed when evaluating the Schottky barrier height Φ 0. Thus the generation-recombination, tunneling and leak currents caused by inhomogeneities and defects at the metal-semiconductor interface were taken into account. Taking the above-mentioned mechanisms and their temperature dependence into consideration in the Schottky diode model, an outstanding agreement between theory and experiment was achieved in a wide temperature range. Excluding the secondary current-transport mechanisms from the total current, a more exact value of the thermionic-emission saturation current I te and thus a more accurate value of Φ b was reached. The barrier height Φ b and the modified Richardson constant A ∗∗ were calculated from the plot of thermionic-emission saturation current I te as a function of temperature too. The proposed method of finding Φ b is independent of the exact values of the metal-semiconductor contact area A and of the modified Richardson constant A ∗∗ . This fact can be used for determination of Φ b in new Schottky structures based on multicomponent semiconductor materials. Using the experimentally evaluated value A ∗∗ = 1.796 × 10 6 Am −2 K −2 for the barrier height determination from I– V characteristics the value of Φ b = 0.881 ± 0.002 eV was reached independent of temperature. The more exact value of barrier height Φ b is a relevant input parameter for Schottky diode computer-aided modeling and simulation, which provided a closer correlation between the experimental and theoretical characteristics.