Schottky Barrier Structures Research Articles

In situ electrical characterization of the Au/n-Si Schottky barrier structure under 1.2 MeV Ar ion irradiation

Understanding the impact of energetic ion irradiation on semiconductor materials and devices is essential for optimizing their electronic applications. This knowledge contributes to the broader goal of tailoring material properties to enhance the overall performance and reliability of semiconductor devices. In this study, we investigate the impact of 1.2 MeV Ar8+ irradiation on Au/n-Si Schottky barrier structures in-situ, as a function of ion irradiation fluence. Electrical characterization was performed in-situ on a single sample to mitigate any variability in device parameters between samples. It is observed that ion irradiation results in an increased Schottky barrier height with a reduction in reverse leakage current. The behavior is attributed to dopant deactivation by the energetic ion irradiation-induced defects near the interface. These results underscore the importance of understanding ion irradiation impacts on semiconductor devices, providing valuable insights for optimizing Schottky diodes in electronic applications.

Photoelectric properties of thin layers of Ag2S quantum dots passivated with thiol-containing molecules

In this work, we studied the electrophysical properties of condensates of colloidal Ag2S quantum dots (QDs), passivated with thiol-containing molecules (thioglycolic acid and L-cysteine) (further, Ag2S/TGA QDs and Ag2S/L-Cys QDs) on indium tin oxide (ITO) substrates. The temperature dependences of the electrical characteristics (conductivity) are analyzed in the temperature range from 300 to 360 K. Facts of the formation of the Schottky barrier structures is obtained. Activation energies of 0.2 eV (Ag2S/L-Cys QDs) and 0.66 eV (Ag2S/TGA QDs) were obtained by the use of linear approximations of current–voltage (I–V) characteristics in Arrhenius coordinates. It is shown that the conductivity of ITO - Ag2S QDs film - Al structure is mainly determined by the Schottky barrier that is formed at the Al-Ag2S QDs film junction. The rectifying contact is formed at the Ag2S film -Al junction due to the lower work function of Al. The I–V characteristics under the optical radiation action were analyzed for the studied sandwich structures. They turned out to be similar for Ag2S/TGA and Ag2S/L-Cys QDs. When a reverse or forward bias voltage is applied to a sandwich structure, in the case of the optical radiation action with a wavelength starting from the its value, corresponding to the most probable exciton transition in the QDs absorption the photocurrent is observed. The found difference (by an order of magnitude) in the photocurrent values of the sandwich structure, based on Ag2S/TGA QDs and Ag2S/L-Cys QDs is related to the smaller thickness of the Ag2S/TGA QDs film.

Electric voltage redistribution effect in Schottky barrier structures based on Si under hydrostatic pressure

The paper presents the results of strain-effect studies in diode structures with Schottky barrier made on the basis of n-Si<P> and n-Si<P,Ni> with resistivities 102 - 105 Ohm·cm under all-round hydrostatic pressure. It is shown that as the resistivity of the base area of the structures increases, its rectifying properties worsens. It was found that the worse of the rectifying property of the surface barrier structures is not due to the presence of compensating impurities, but depends only on the resistance of the base area. In the Schottky barrier structures based on n - Si<P,Ni> with resistivities ~104 and 105 Ohm·cm the potential barrier is almost not formed. For the first time it was found that in structures with Schottky barrier under all-round hydrostatic pressure there is high strain sensitivity due to redistributions of electric voltage between the contact and the base area.

Optimization design of GaAs-based betavoltaic batteries with p–n junction and Schottky barrier structures

This paper presents the calculation model and the optimization design of the GaAs-based betavoltaic batteries with p–n junction and Schottky barrier structures. First of all, by using the Monte Carlo code, the transport process and energy deposition distribution of the source beta particles in the GaAs material are simulated. The relationships between the output parameters of batteries and the physical parameters of energy converter such as p–n junction depth, Schottky metal thickness, depletion region width and doping concentrations are discussed through the numerical calculation. For the GaAs p–n junction battery, the maximum output power density of 0.135 can be achieved when the junction depth is x j = 0.05 , the doping concentrations are and . Meanwhile, the short-circuit current density, open-circuit voltage, filling factor and energy conversion efficiency are 0.254 , 0.638 V, 83.3% and 2.63%, respectively. Among the selected metals of Au, Pd, Ni and Pt for the GaAs Schottky barrier diodes, the Pt-GaAs battery has the best output performance due to its large work function. The maximum output power density of 0.169 can be achieved when a 20 nm thick Schottky metal Pt is selected and the doping concentration is . The associated output parameters of the battery are 0.234 , 0.835 V, 86.5% and 3.29%, respectively.

Investigation of radiation-associated deformation in the electrical properties of metal-polymer semiconductor

In the present study, rubrene-based Schottky barrier structures have been formed by using the evaporation technique to investigate the conductance–voltage (G–V) and capacitance-voltage (C–V) values of the effect of the 60Co gamma-ray irradiation. The conductance and capacitance values were measured before and after 60Co gamma-ray radiation at 100 kHz, 500 kHz and 1 MHz. The frequency-dependent effects of interface state density and series resistance with and without irradiation in dark were analyzed at room temperature. The analysis results imply that values of forward and reverse C characteristics decrease the rate depending on gamma-ray irradiation and the increment of voltage due to the exchange of majority carriers between the majority carrier band of semiconductor and interface states. The irradiation dose and frequency increase show irradiation dispersion at the accumulation region when an A.C. signal is applied to the semiconductor structures. The G–V characteristics of rubrene-based Schottky barrier structures change with gamma radiation dose at different frequencies. Also, these characteristics relate to the density of the interface states. The analyses reveal that D it values decrease with the increase in frequency before 60Co gamma-ray irradiation. These values also decrease with the increase in frequency at the same radiation doses after 60Co gamma-ray irradiation. They decrease with the increase in irradiation doses at the same frequency, except for 100 kHz. Experimental results indicate that rubrene-based Schottky barrier structures can be altered using 60Co gamma-ray irradiation. The experimental contributions indicate a substantial step forward in the structure-function relationship in the benchmark organic semiconductors.

Fabrication, structural and electrical characterization of Au/ (CuSe-polyvinyl alcohol)/n-Si (MPS) Schottky barrier structures

The copper selenide (CuSe) nanostructures with different pH values are prepared by an ultrasound-assisted technique. The spectroscopic, morphological and structural characteristics of prepared nanomaterials were investigated via different methods. The XRD patterns depicted that the samples have crystalline structures. HRTEM images show the nanostructures size and it also showed that the morphology changed with changing pH value. FT-IR Spectroscopy confirmed the formation of CuSe and evaluates the changes induced by pH variation and in the energy variation between functional groups. Diffuse reflectance spectroscopy (DRS) results demonstrate the absorption regions of CuSe nanostructures are 300–400 nm. Some electrical parameters of the manufactured Au/(CuSe-PVA)/n-Si Schottky barrier diodes (SBDs) were obtained from the impedance measurements (capacitance/conductance-voltage) in the frequency range between 10 kHz and 1 MHz. The amounts of capacitance (C) and conductance (G/ω) were found as are strongly frequency and voltage dependent. While the values of depletion layer width (Wd) and barrier height (ΦB (C-V)) increase with increasing frequency, the concentration of donor atoms (ND) decreases. Both the voltage-dependent profile of surface states (Nss) and series resistance (Rs) were measured and estimated using the low-high frequency capacitance and Nicollian-Brews methods, respectively. These results showed a distinctive peak in the depletion region because of the spatial distribution of the Nss between (CuSe-PVA) and n-Si in the band-gap of Si. Obtained results indicated that the Nss, Rs, and interfacial (CuSe-PVA) layer are significant parameters for the electrical properties.

Analysis of the carrier conduction mechanism in 100 MeV O7+ ion irradiated Ti/n-Si Schottky barrier structures

The electrical transport properties of Ti/n-Si Schottky barrier structure irradiated by 100 MeV O7+ ion has been studied between 120 K and 320 K and compared with unirradiated Ti/n-Si structure to gain the understanding of carrier transport mechanism in irradiated devices. The barrier parameters have been extracted using the current-voltage (I–V) characteristics in forwarding bias. It is found that Schottky barrier height (zero bias) increases while the value of ideality factor becomes smaller with increasing temperature. Recent models consisting of inhomogeneous barrier potential at the metal-semiconductor (MS) interface have been used to explain the behavior of barrier parameters. The role played by the high energy ions at MS interface during irradiation is considered to understand the observed behavior.

A novel surface area to volume ratio estimation technique for nanohemisphere contacted Schottky barrier structures

Nanostructured metal-semiconductor interfaces, also known as Schottky barriers, exhibit remarkable electronic properties. The surface morphology of nanostructure contacted Schottky barriers has a significant effect on its current-voltage (I-V) characteristics, which is crucial for high-performance device applications. In this work, we present a surface area to volume ratio (SVR) estimation technique for nanohemisphere Schottky interfaces. By applying Gauss’s law, i.e. without deviating from first principle, we expand the formulation of thermionic emission theory to incorporate surface area and volume. The proposed technique has been assessed by comparison against AFM measured surface characteristics of fabricated Pt/ZnO nanohemisphere structures. Results show that the proposed technique has a high accuracy to within several percent from surface measurements. This technique provides access to SVR while eliminating the need for direct surface characterization, which can be an instrumental tool for the design and analysis of surface-sensitive devices, such as sensors.

Schottky Barrier Infra-Red Sensors Sensitive to Radiation of Quantum Energy Higher Than the Potential Barrier Height

The technology to obtain a silicide Pt/Ir mixture and Pt/Ir–Si photosensitive structures with a Schottky barrier in the middle IR area is developed. It is found that the main way to detect Pt/IrSi–р–Si structures is through the photoemission of Pt/IrSi holes into silicon. Moreover, the maximal photosensitivity is observed when the Pt/IrSi is not thicker than the free path length of the holes (less than 460 A). The energy band diagram of the Schottky barrier structures based on the Pt/IrSi–Si contact is plotted. It is determined that the electron affinity of Pt/IrSi varies within 4.7–5.26 eV depending on the operational conditions of its formation.

Schottky Barriers Based on Nanoporous InP with Gold Nanoparticles.

Schottky barrier structures based on nanoporous InP with inclusion of Au nanoparticles and evaporated semitransparent Au film have been made. The spectra of short-circuit photocurrent in the visible range and current-voltage characteristics have been measured. Prepared structures are characterized by increased photocurrent due to the microrelief interface and surface plasmon excitation in gold nanoparticles as well as increased surface recombination especially in the short wavelength region.

Osoblyvosti perenesennya zaryadu v strukturakh Mo/n-Si z bar"yerom Shotky

Forward and reverse current-voltage characteristics of Mo/n-Si Schottky barrier structures have been studied experimentally in the temperature range 130-330 K. The Schottky barrier height is found to increase and the ideality factor to decrease, as the temperature grows. The obtained results are analyzed in the framework of a non-uniform contact model. The average value and the standard deviation of a Schottky barrier height are determined to be 0.872 and 0.099 V, respectively, at T = 130220 K and 0.656 and 0.036 V, respectively, at T = 230330 K. Thermionic emission over the non-uniform barrier and tunneling are shown to be the dominant processes of charge transfer at a reverse bias voltage.

Electro-Deposited PdNi-Si Schottky Barrier Hydrogen Sensors with Improved Time Response

Abstract Hydrogen sensor based on electrodeposited PdNi-Si Schottky barriers have been fabricated with a gradient structure in the PdNi concentration in a single electrodeposition run through variation of the deposition potential. By varying the electrodeposition potential after a fixed amount of charge, we are able to create various Schottky barrier structures. The resulting sensors in the back to back diode configuration show very low idle leakage current and high sensitivity to hydrogen. The structure with increased Ni concentration at the PdNi-Si interface shows dramatically improved time response as compared to the sample with uniform PdNi concentration.

The electrical characterization and response to hydrogen of Schottky diodes with a resistive metal electrode—rectifying an oversight in Schottky diode investigation

Schottky-barrier structures with a resistive metal electrode are examined using the 4-point probe method where the probes are connected to the metal electrode only. The observation of a significant decrease in resistance with increasing temperature (over a range of ∼100 K) in the diode resistance–temperature (RD–T) characteristic is considered due to charge carrier confinement to the metal electrode at low temperature (high resistance), with the semiconductor progressively opening up as a parallel current carrying channel (low resistance) with increasing temperature due to increasing thermionic emission across the barrier. A simple model is constructed, based on thermionic emission at quasi-zero bias, that generates good fits to the experimental data. The negative differential resistance (NDR) region in the RD–T characteristic is a general effect and is demonstrated across a broad temperature range for a variety of Schottky structures grown on Si-, GaAs- and InP-substrates. In addition the NDR effect is harnessed in micro-scaled Pd/n-InP devices for the detection of low levels of hydrogen in an ambient atmosphere of nitrogen.

Determination of the parameters for the back-to-back switched Schottky barrier structures

The Cr/ n-GaAs/Cr and Ag/ p-GaAs/Ag metal–semiconductor–metal (MSM) Schottky contacts have been fabricated by reactive radio frequency (RF) sputtering system. The current–voltage ( I – V ) and capacitance–voltage ( C – V ) characteristics of the devices have been investigated in the temperature range of 80–316 K for the back-to-back switched Schottky barrier contacts. These measurements establish that the room temperature barrier height determined from reverse branch of the current–voltage characteristics is close to the value obtained from capacitance–voltage measurements.

Heat- and radiation-resistant contacts to SiC made on the basis of quasi-amorphous ZrB2 films

The radiation and thermal stability of the Schottky-barrier structures deposited by the magnetron sputtering of zirconium diboride onto the (0001) face of the Lely-grown n-6H(15R)SiC single crystals with the uncompensated-donor concentration of ∼1018 cm−3 was investigated by the methods of the I–V and C–V characteristics combined with the layer-by-layer Auger analysis. It is shown that the use of quasi-amorphous ZrB2 films when manufacturing contacts on n-6H(15R)SiC leads to no changes in the Schottky-barrier characteristics during rapid thermal annealing to 800°C in the range of 60Co γ-ray irradiation doses of 103–107 Gy.

Theoretical Investigation of GaN-Based Diodes with a Recessed Composite Schottky-Barrier Structure

We have performed the two-dimensional ensemble Monte Carlo simulation of GaN-based diodes with various Schottky-barrier structures. Simulation results indicate that the recessed composite Schottky-barrier structure is effective for improving the trade-off relationship between forward turn-on and reverse breakdown voltages. The optimized recessed composite Schottky-barrier diode, having low and high barrier heights of 0.4 and 0.8 eV, respectively, exhibited a low turn-on voltage of 0.21 V, while maintaining a high-breakdown voltage of 373 V. The proposed Schottky-barrier diode is a promising tool for applications in RF-to-DC conversion circuits with high efficiencies.

Electron emission from multilayer ensembles of vertically coupled InAs quantum dots in an n-GaAs matrix

Electron emission from multilayer arrays of vertically coupled InAs quantum dots into the n-GaAs matrix in Schottky-barrier structures (electron concentration n ≈ 2 × 1016 cm−3) is studied by admittance spectroscopy. It is established that, in the temperature region below ∼70 K, electron emission in a rate range of 3 × 104–3 × 106 s−1 proceeds via thermally activated tunneling through intermediate virtual states. As the number of layers in the quantum dot array increases from three to ten, a decrease in the electron emission rate is observed.

Defect states in pentacene thin films prepared by thermal evaporation and Langmuir–Blodgett technique

We investigate defect states in pentacene thin films (PTFs) prepared by two different deposition techniques: standard thermal evaporation in high vacuum and the Langmuir–Blodgett (LB) technique. Time domain capacitance–voltage (C–V) and charge deep-level transient spectroscopy (DLTS) techniques were employed. C–V measurements indicate that Schottky barrier structures on both types of PTFs exhibit a common behavior: the thinner the PTF, the closer the measured C–V curve to the ideal shape for the Schottky barrier. Charge DLTS measurements show a peak with an activation energy of about 0.70eV above Ev and an attempt-to-escape frequency of 3×1014s−1 for PTFs deposited by thermal evaporation. For PTFs prepared by LB technique two deep-levels with activation energies of 0.20eV and 0.21eV, and an attempt-to-escape frequencies of 2×107s−1 and 2×106s−1, respectively, are found. The amplitude of the charge DLTS signals increases with decreasing PTF sample thickness for both deposition techniques. The observed defects can not be removed by annealing in vacuum. The origin of defects responsible for the measured charge DLTS spectra is discussed.

Semiconductor(BaSi 2)/metal(CoSi 2) Schottky-barrier structures epitaxially grown on Si(1 1 1) substrates by molecular beam epitaxy

We successfully demonstrated epitaxial growth of semiconductor (BaSi 2)/metal(CoSi 2) Schottky-barrier structures on Si(1 1 1), for the first time, by molecular beam epitaxy (MBE). The interface between the CoSi 2 and BaSi 2 layers was found to be sharp from transmission electron microscopy (TEM) observations. The current–voltage characteristics measured at room temperature showed clear rectifying properties. When positive bias was applied to the CoSi 2 layer with respect to the BaSi 2 layer, the current increased exponentially. Electron diffraction patterns obtained using reflection high-energy electron diffraction (RHEED) and TEM are discussed.

Effect of the bias electric field on the spectral distribution of the photodielectric effect in the Schottky-barrier structures based on the cadmium-zinc telluride crystals

Spectral dependences of effective values of the real and imaginary parts of the low-frequency permittivity of the Cd1−xZnxTe crystals (x=0.12–0.16) with the Schottky barrier fabricated on the surface are measured. It is found that the boundary wavelengths of the characteristic portions of the measured dependences represented in the complex plane correspond to energies of photons, which cause the radical variations in the state of negatively charged and electrically neutral localized acceptor states. The variations in the energy spectrum of the localized states, which are determined by the magnitude and polarity of the electric bias applied to the Shottky barrier, are found.