Schottky Diodes Research Articles

Proton irradiation Of Ga2O3 Schottky diodes and NiO/Ga2O3 heterojunctions.

p-NiO/n-Ga2O3 heterojunction (HJ) diodes exhibit much larger changes in their properties upon 1.1MeV proton irradiation than Schottky diodes (SDs) prepared on the same material. In p-NiO/Ga2O3 HJ diodes, the narrow region adjacent to the HJ boundary is found to contain a high density of relatively deep centers with levels near EC-0.17eV and a depleted region in the immediate vicinity of the HJ boundary. The series resistance of the HJ diodes is slightly higher than for the Schottky diodes and shows a temperature dependence with activation energy ~ 0.12eV, like the temperature dependence of the NiO film resistivity. Irradiation with 1.1MeV protons leads to a decrease of the hole concentration in the NiO, with a high carrier removal rate of ~ 1.3 × 105cm-1 and a strong compensation of the interfacial region where the concentration of the EC-0.17eV centers decreases with a high rate of ~ 7 × 103cm-1. The combined action of these two effects gives rise to the much stronger increase of the series resistance of the HJ diodes compared to Schottky diodes. The observed differences between the radiation response of the HJs and SDs cannot be credibly attributed to the changes of the density of any of the deep electron and hole traps detected in our experiments.

Methodology of Production of Photo-Sensitive Elements on Ptsi Basis

Schottky barrier diodes based on PtSi-Si contact can be used as detectors for registration of radiation in the infrared spectral region. However, the quantum efficiency of such receivers is very low compared to photodetectors based on narrow-gap semiconductors and p-n junctions. To increase the quantum efficiency of Schottky receivers, as it will be shown below, they are made in the form of the so-called “optical cavity”, and the thickness of PtSi should not exceed 100 A0. For this purpose we have developed a technological mode of multilayer metallization to obtain thin PtSi-Si contacts.

Pt/β-Ga2O3 Schottky devices enabling 60 Hz half-wave rectification for power-efficient pixel display

Beta-phase gallium oxide, β-Ga2O3, in transistors and diodes has been reported due to its distinctive electrical characteristics, such as wide bandgap, low leakage current, and high breakdown electric field. However, besides such conventional basic devices, more advanced device applications using β-Ga2O3 are always necessary. Here, we report on the dynamic behavior of Pt/β-Ga2O3-based Schottky diode for power-efficient organic light emitting display (OLED). Two Schottky diodes are back-to-back connected in series to form a half-wave rectifier circuit and finally integrated with an OLED diode pixel. When AC voltage is applied to the circuit at a frequency greater than 60 Hz, blinking of the OLED light is indistinguishable to human eyes. By way of the rectifier circuit, the OLED pixel efficiently saves more than 35% of the power that should be consumed by applying DC voltage.

Investigation of traps in halide vapor-phase epitaxy-grown β-Ga2O3 epilayers/n+-Ga2O3 using deep-level transient spectroscopy

Abstract A detailed investigation of deep traps in halide vapor-phase epitaxy (HVPE)-grown β-Ga2O3 epilayers has been done by performing deep-level transient spectroscopy (DLTS) from 200 K to 500 K on Pt/β-Ga2O3 and Ni/β-Ga2O3 Schottky diodes. Similar results were obtained with a fill pulse width of 100 ms irrespective of the different Schottky metal contacts and epilayers. Two electron traps at E2 (E C–E T = 0.65 eV) and E3 (E C–E T = 0.68–0.70 eV) with effective capture cross-sections of 4.10 × 10−14 cm2 and 5.75 × 10−15 cm2 above 300 K were observed. Below 300 K, a deep trap with a negative DLTS signal peak was also observed at E1 (E C–E T = 0.34–0.35 eV) with a very low capture cross-section of 3.28 × 10−17 cm2. For a short pulse width of 100 μs, only two electron traps, E2 and E3, at energies of 0.72 eV and 0.73 eV were observed, and one order of higher corresponding effective capture cross-sections. All traps were found to be unaffected by the electric field during the field-dependent DLTS study. From the filling pulse width dependence DLTS study, a decrease in the capacitance transient amplitude with the increasing pulse width was observed opposite to the capture barrier kinetics of the traps and attributed to the emission of carriers during the capture process. Trap concentrations were found to be high at the interface using depth profiling DLTS. Based on the available literature, it is suggested that these traps are related to FeGa, Fe-related centers, and complexes with hydrogen or shallow donors, and might be affected or generated during metallization by the electron beam evaporator and chemical mechanical polishing.

TCAD simulation on an UACCUFET inserted with 3C/4H–SiC hetero-crystalline junctions for accumulation-channel and fly-back

Due to high channel mobility, SiC accumulation-channel field-effect transistors (ACCUFETs) exhibit important research and application values in high-frequency and large-power fields, but still encounter poor reverse recovery, etc. An enhancement-mode U-shaped gate ACCUFET integrated with 3C/4H–SiC hetero-crystalline junctions (HCJs) and semi-super-junction (SSJ) is constructed, where a (n−)4H–SiC-layer in (n)3C–SiC/(n−)4H–SiC HCJ is adopted to form accumulation-channel for conduction due to field-effect, another HCJ composed of (n)3C–SiC and (n)4H–SiC drift region is employed for fly-back under low cut-in voltage (VF) to shorten reverse recovery time (trr). Additionally, a SSJ is used to raise the breakdown voltage (VB). The device structure and performance are optimized by the Silvaco TCAD, which illustrates the values of VB and static figure of merit (FOMHM) are increased by 15.6 % and 5.6 % respectively compared to those of the counterpart with Schottky barrier diode. This paper can provide new ideas for devising high-performance ACCUFETs.

Measuring the radiation hardness of terahertz devices for space applications

The application of terahertz technology in space is frontier for the development of 6G technologies. Terahertz transceiver devices based on gallium arsenide Schottky barrier diodes (GaAs SBDs) have the characteristics of small size, light weight and low power consumption, making them suitable for application on spacecraft. However, there is currently a lack of experimental assessments on their space adaptability. Here, we study the radiation hardness of terahertz devices to determine their adaptability in complex space environments. We exposed GaAs SBDs and terahertz multipliers as typical terahertz devices to gamma rays and protons. The experimental results showed that the terahertz devices exhibited good tolerance to protons, but prolonged exposure to gamma rays could significantly increase the leakage current of the GaAs SBDs and alter its C-V characteristics, leading to the failure of the terahertz multiplier. Nevertheless, the terahertz devices maintained a good level of radiation hardness, making them highly suitable for use in Low Earth Orbit (LEO) satellites. The comparison between the results of proton and gamma ray tests indicated that the terahertz devices exhibited high inherent radiation hardness against displacement damage but were more sensitive to ionization damage, requiring higher shielding requirements.

A semiconducting supramolecular Co(II)-metallogel based resistive random access memory (RRAM) design with good endurance capabilities.

A highly efficient approach for synthesizing a supramolecular metallogel of Co(II) ions, denoted as CoA-TA, has been established under room temperature and atmospheric pressure conditions. This method employs the metal-coordinating organic ligand benzene-1,3,5-tricarboxylic acid as a low molecular weight gelator (LMWG) in DMF solvent. A comprehensive analysis of the mechanical properties of the resulting supramolecular Co(II)-metallogel was conducted through rheological investigation, considering angular frequency and thixotropic study. The hierarchical rocky network structure of the supramolecular Co(II)-metallogel was unveiled using field emission scanning electron microscopy (FESEM). Transmission electron microscopic (TEM) analysis showed rod-shaped structures via low-magnification high angle annular dark field (HAADF) bright field scanning transmission electron microscopic (STEM) imaging, while energy dispersive X-ray (EDX) elemental mapping confirmed its primary chemical constituents. The formation mechanism of the metallogel was examined via fourier transform infrared spectroscopy (FTIR) spectroscopy. The nature of the synthesized CoA-TA metallogel was affirmed through powder X-ray diffraction (PXRD) analysis. Furthermore, this study involved fabrication of Schottky diode structures in a metal-semiconductor-metal geometry based on cobalt(II) metallogel (CoA-TA), enabling observation of charge transport behavior. Remarkably, a resistive random access memory (RRAM) device utilizing cobalt(II) metallohydrogel (CoA-TA) demonstrated bipolar resistive switching at room temperature and under ambient conditions. The switching mechanism was investigated, revealing the formation and rupture of conductive filaments between metal electrodes that govern the resistive switching behavior. This RRAM device exhibited an impressive ON/OFF ratio (~ 414) and exceptional endurance over 5000 switching cycles. These structures offer great potential for diverse applications such as non-volatile memory design, neuromorphic computing, flexible electronics and optoelectronics. Their advantages lie in their fabrication process, reliable resistive switching behavior and overall performance stability.

Impacts of single Shockley-type stacking faults on current conduction in 4H-SiC PiN diodes

The impacts of single Shockley-type stacking faults (1SSFs) on the electrical characteristics of 4H-SiC PiN diodes were examined by fabricating the PiN diodes containing the 1SSF monolayer in the active area with a covering ratio of unity and evaluating the forward current–voltage (I–V) characteristics at various temperatures from 296 to 523 K. The measured I–V characteristics were compared with the previous results for Schottky barrier diodes (SBDs) containing the 1SSF monolayer. Based on the comparison, we clarified the similarity and differences between the impacts of the 1SSFs on the unipolar and bipolar conductions. The forward current conduction of the PiN diodes is limited by the 1SSF similar to that of the SBDs, while the forward current in the PiN diodes exceeds that in the SBDs at elevated temperatures. The difference was attributed to the contribution of hole and recombination currents, the insights into which were obtained by analyzing several experimental results, including dependences of the forward current on the temperature and thickness of the blocking-voltage layer. A simulation analysis was also conducted by adopting the model proposed in the previous study.

Huge photosensitivity gain combined with long photocurrent decay times in various polymorphs of Ga2O3: effects of carriers trapping with deep centers

Abstract The materials system of ultra-wide bandgap Ga2O3 has already shown great promise in the field of solar-blind photodetectors with high photoresponsivity, high photoresponsivity gain and low dark current. These promising results have been achieved on Ga2O3 films of different polymorphs and by different methods, often not with particularly high crystalline quality. In fact, it would often seem the case that the lower the crystalline quality of the films, the higher the photosensitivity and its gain. This, however, is in most cases accompanied by unusually long photocurrent build-up and decay times. We show that the experimental results can be explained by models in which the high photosensitivity gain is related to the effects of holes being trapped by deep states that, in Schottky diodes, results in the decrease of the Schottky barrier height with consequent increase of electron current, and in Metal-Semiconductor-Metal (MSM) structures additionally gives rise to the usual gain increase due to the increased concentration and lifetime of electrons. We present and discuss the models describing the effects in Ga2O3 Schottky diodes, MSM structures, unipolar and bipolar heterojunctions and propose possible candidates for the role of the hole traps in different Ga2O3 polymorphs. We also discuss the existing results for the photocurrent build-up and decay times and offer possible explainations of the observed temperature dependences of the characteristic times where such data are present.

Point-to-multipoint beam-steering terahertz communications using a photonics-based leaky-wave transmit antenna

Abstract We report on the successful implementation of a photonic-based beam steering approach for point-to-multipoint terahertz (THz) communications. The frequency-agile radiation properties of a THz leaky-wave antenna connected to a photodiode are utilized in the remote transmitter for generating multiple individually steerable THz beams. The approach benefits from the ultra-wide frequency tunability of optical heterodyne systems for frequency-agile THz beam steering. Moreover, the approach allows to exploit high performance and mature optical modulation techniques for generating THz beams with a high data capacity. In the THz receiver, a carrier frequency insensitive envelope THz detector based upon a single Schottky-barrier diode is used. In detail, THz communications in the 300 GHz band (WR3.4) with a maximum steering angle up to 90° is reported. Experimentally, for single steerable THz beam operation, a record high data rate of 35 Gbit/s at a wireless distance of 30 cm is achieved using two-level pulse amplitude modulation. Also, longer wireless distances up to 110 cm with 5 Gbit/s are demonstrated. Furthermore, point-to-multipoint THz communications is reported using two individually steerable THz beams carrying 10 Gbit/s and 5 Gbit/s over 70 cm and 50 cm, respectively.

Self-assembly monolayer impact on Schottky diode electrical properties

This study examines the electrical and charge transport properties of p-Si/TiO2/self-assembly monolayer (SAM)/Al type Schottky diodes. The diodes were fabricated by applying the SAM molecule 4′-[(3-methylphenyl)(phenyl)amino]biphenyl-4-carboxylic acid (CT21) onto titanium dioxide (TiO2) synthesized via the sol-gel method. The key parameters, including the ideality factor (n), series resistance (Rs), and barrier height (∅b), were used to assess the impact of CT21 on diode performance. Experimental results revealed that using CT21 at the TiO2/Al interface significantly enhances diode performance. The n decreased from 3.8 in the control diode to 1.9 with CT21. Rs was substantially reduced, and the ∅b increased. The rectification ratio improved from 1x104 in the control diode to 1.1x105 in the CT21-modified diode. These enhancements, due to the CT21 molecule's ability to reduce interface states (Nss) and improve surface properties, underscore the potential of SAM coatings to open a new window in nanoelectronics with better performance and reliability.

Numerical Investigation of G–V Measurements of metal – A Nitride GaAs junction

In this study, a Schottky diode consisting of Au/GaN/GaAs was fabricated using a radiofrequency nitrogen plasma source. The voltage-conductance characteristics (G/ω-V) of this diode structure were investigated at room temperature. To interpret the changes in the electrical properties of the nitrided GaAs-based Schottky structure, we developed a simulation program. This program employs a numerical model to calculate the G-V characteristics, allowing us to validate the experimental measurements conducted on the Schottky diodes. The geometric model used in our simulation considers not only the GaN layer formed between the metal and GaAs substrate but also the density and distribution of trapped states within the band gap. The program utilizes the numerical resolution of the Poisson and continuity equations to calculate the electrostatic potential and the concentrations of both n and p mobile carriers. These parameters are then used to determine the electric charge, current, capacitance, and conductance. The simulation results were subsequently compared to the experimental measurements to ensure their accuracy.

Construction of Schottky barrier diode with a novel one-dimensional Cu(II)-based coordination polymer

Utilization of different kinds of materials in the fabrication of electronic device is considered as one of their most prominent employments. For modern civilization development of efficient electronic devices is extremely helpful not only due to their technological aspect but also for their laboratory to land applications. Keeping in mind of the above issues, a copper(II)-based zigzag one dimensional coordination polymer [Cu(4-dpds)(4-cba)2]n (where 4-dpds represents 1,2-di(pyridine-4-yl)disulfane and 4-cba represents 4-chloro benzoate anion) has been synthesized and well-characterized through X-ray single crystal diffraction analysis, powder X-ray diffraction analysis, thermogravimetric analysis, absorption spectral analysis and infra-red spectral analysis. Structural characterization through single crystal X-ray diffraction analysis reveals that the zigzag wave like architecture has been generated due to the presence of S-S linked ligands 4-dpds and strong hydrogen bonding interactions play pivotal role in the development of the supramolecular aggregate. Interestingly, the optical band-gap (2.15 eV) obtained from absorption spectra and the electrical conductivity at room temperature (measured as 9.73 × 10−4 S cm-1) revealed the semiconducting nature of the coordination polymer. The theoretical calculation projected HOMO-LUMO energy gap (2.11 eV) and the Fermi level (near to valence band) estimated from DOS also justified the p-type behavior of the derived material. The device fabricated by sandwiching the coordination polymer in between ITO coated glass substrate and metallic aluminum, was observed to exhibit non-linear rectifying nature in current-voltage characteristic plot. Therefore it is obvious that these kinds of easily synthesizable lower dimensional coordination polymers can be considered as potential candidates in application of Schottky like devices and also helpful for technological advancement as well as for the up-gradation of future research in the corresponding field.

Development of a compact and portable diamond-based detection system for dosimetry and microdosimetry in ion beam therapy.

Ion beam therapy techniques have advanced significantly in the past two decades. However, the development of dosimetric verification methods has lagged. Traditional dosimetry, which offers a macroscopic view of the absorbed dose, fails to address the micrometric-scale stochastic effects crucial for understanding biological responses. To bridge this gap, microdosimeters are used to assess physical quantities correlated with radiation effects. This work reports on the design and testing of a novel detection system based on synthetic single crystal diamond. The system is capable of simultaneously performing dosimetric and microdosimetric characterizations of clinical ion beams. The detector incorporates two active components configured as diamond Schottky diodes, both integrated on a single crystal diamond substrate. In particular, one very small element (sensitive area 0.0078 mm2) was designed to evaluate microdosimetric metrics, while the other large one (sensitive area 4.2 mm2) was designed to measure the absorbed dose to water. Diamond detectors were characterized using the ion beam induced charge (IBIC) technique, employing a 1MeV protons microbeam. The IBIC map of the diamond detector shows two distinct sensitive areas with quite uniform sensitivity, well contained within the metallic contact regions. Dedicated front-end electronic circuits were designed and implemented for both the dosimetric and microdosimetric signals. These circuits, along with the integrated diamond detector, were embedded in an aluminum waterproof housing to minimize electronic interference. This configuration enables a compact, portable setup compatible with water phantoms. Laboratory tests with alpha particles yielded promising results, demonstrating stable and reproducible responses with a good signal-to-noise ratio.

A two-dimensional TaGe2P4–WSi2As4 van der Waals heterojunction: a near-ideal rectifier

Searching for suitable 2D metal-semiconductor interfaces to design high-performance Schottky diodes is essential for the continuous miniaturization of devices. Herein, by using the first-principles calculations, we propose a near-ideal two-dimensional van der Waals rectifier consisting of the monolayer TaGe2P4 metal and the WSi2As4 semiconductor with ultra-clean interface and free dangling bonds. The van der Waals heterojunction has a p-type Schottky contact at both the vertical and lateral interfaces. The Schottky barriers lead to the asymmetry of electronic transport under the positive and negative bias voltages, thus resulting in a remarkable rectification behavior. The rectifying properties can be improved by regulating the length of the semiconductor and the overlapping region, and an ultra-high rectification ratio of 107 is obtained at a low bias voltage. The origin of the rectification effect and the regulating mechanism are explained in terms of the projected local density of states, transmission eigenstates, potential drop, and transmission spectra. It is found that increasing the relative length of the semiconductive part in the device enlarges the width of the Schottky barrier, which largely reduces the reverse current dominated by the electron tunneling. At the same time, little affects the positive current and thus leads to a significant improvement in the rectification performance. These results suggest that the TaGe2P4–WSi2As4 van der Waals heterojunction has promising application as a near-ideal rectifier.

Enhancement of positive bevel β-Ga2O3 trench MOS barrier Schottky diode by post-etching treatment

Enhancement of positive bevel β-Ga2O3 trench MOS barrier Schottky diode by post-etching treatment

Effects of 10 keV Electron Irradiation on the Performance Degradation of SiC Schottky Diode Radiation Detectors

The silicon carbide (SiC) Schottky diode (SBD) detector in a SiC hybrid photomultiplier tube (HPMT) generates signals by receiving photocathode electrons with an energy of 10 keV. So, the performance of the SiC SBD under electron irradiation with an energy of 10 keV has an important significance for the application of the SiC-HPMT. However, studies on 10 keV radiation effects on the SiC SBDs were rarely reported. In this paper, the performance degradation of the SiC SBDs irradiated by 10 keV electrons at different fluences was investigated. After the irradiation, the forward current of the SiC SBDs increased, and the turn-on voltage decreased with the irradiation fluences until 1.6 × 1016 cm−2. According to the capacitance–voltage (C-V) curves, the effective doping concentration increased slightly after the irradiation, and an obvious discrepancy of C-V curves occurred below 5 V. Moreover, as a radiation detector, the peak position of the α-particles’ amplitude spectrum changed slightly, and the energy resolution was also slightly reduced after the irradiation due to the high collection charge efficiency (CCE) still being larger than 99.5%. In addition, the time response of the SiC SBD to the 50 ns pulsed X-ray was almost not affected by the irradiation. The results indicated that the performance degradation of the SiC SBD irradiated at the fluence of 1.5 × 1017 cm−2 would not result in a deterioration of the properties of the SiC-HPMT and showed an important significance for the supplement of the radiation resistance of the SiC SBD radiation detector.

CsSnBr3 and Cs3Bi2Br9: Structural, Optical Characteristics, and Application in a Schottky Barrier Diode

The search for alternatives to Pb‐based perovskites, due to concerns about stability and toxicity, has led to the exploration of Pb‐free options. Tin (Sn) and bismuth (Bi) are promising candidates, given their similar ionic radii to Pb and the isoelectronic nature of Pb2+ and Bi3+, which suggest comparable chemical properties. Among these, CsSnBr3 and Cs3Bi2Br9 are relatively underexplored but offer lower toxicity and enhanced stability while demonstrating optoelectronic properties suitable for various applications. In this study, CsSnBr3 and Cs3Bi2Br9 nanocrystals are synthesized using a colloidal method and integrated into Schottky diodes. X‐ray photoelectron spectroscopy analysis of the surface chemistry confirms improved thermal and phase stability compared to Pb‐based perovskites. Schottky diode parameters, including ideality factor, barrier height, and series resistance are assessed using conventional thermionic emission, modified Cheung's, and Norde's models. The Cs3Bi2Br9‐based Schottky diode exhibits superior electrical performance with the lowest series resistance and optimal barrier height. Electrical impedance spectroscopy results indicated that CsSnBr3 has higher resistances and lower capacitances than Cs3Bi2Br9, reflecting lower charge carrier mobility and more defects, although the R1C1 regions in both materials demonstrated faster charge dynamics, making them ideal for high‐speed applications.

650 V vertical Al0.51Ga0.49N power Schottky diodes

We report high-Al-composition (HAC) Al0.51Ga0.49N vertical power Schottky barrier diodes (SBDs) on sapphire substrates grown by metal organic chemical vapor deposition. The fabricated vertical HAC AlGaN-on-sapphire SBDs exhibit a low turn-on voltage of 1.31 V, a high on/off ratio of ∼107, a low ideality factor of 1.35, and a high breakdown voltage of 662 V.

The relationship of voltage variations in the third quadrant and the Schottky area ratios in a 4H-SiC SBD-embedded MOSFET

Based on the measured and the TCAD simulation results, this paper provides a detailed description of the third quadrant characteristics of the Schottky barrier diode (SBD) embedded MOSFETs with different Schottky area ratios of 2.6 %, 5.3 %, and 14.7 %. As the Schottky area ratio increases, the shift of the third quadrant turn-on voltages of the MOSFETs influenced by the gate voltage decreases. The shift rates in the conventional MOSFET and SBD-embedded MOSFETs are from 57.2 % to 0 % when Vgs changes from 0 V to −4 V. The shift rate becomes 0 % when the Schottky area ratio is larger than 5.3 %. Simultaneously, the TCAD simulation results and the measured results indicate that the SBD-embedded MOSFETs can effectively suppress the conduction of the low barrier diode and the body diode.Furthermore, the SPICE models were built to explain the physics mechanisms. The fitting error between the measured and fitting results is as low as 1.3 % among the models with the different Schottky area ratios.