Silicon Schottky Diodes Research Articles

Current crowding in graphene–silicon schottky diodes

The performance of the Graphene/Si (Gr/Si) Schottky interface and its potential in future electronics strongly rely on the quality of interconnecting contacts with external circuitry. In this work, we investigate the dominating and limiting factors of Gr/Si interfaces designed for high light absorption, paying particular attention to the nature of the contact failure under high electrostatic discharge (ESD) conditions. Our findings indicate that severe current crowding at contact edges of the graphene is the dominating factor for the device breakdown. Material degradation and electrical breakdown are systematically analyzed by atomic force, Raman, scanning electron, and energy-dispersive x-ray spectroscopies. This work enlists the robustness and limitations of Gr/Si junction in photodiode architecture under high ESD conditions that can be used as general guidelines for 2D–3D electronic and optoelectronic devices.

PEI N-doped graphene quantum dots/p-type silicon Schottky diode

Graphene Quantum Dots (GQDs) are graphene nanoparticles with exceptional properties and a remarkable material for new technologies. Especially, GQDs/semiconductor junctions (GQDs/S), which have a high potential to open doors to new fields of study such as sensing, detection, and communication have started to attract great attention in the scientific community in the last few years. Functionalization of GQDs with several functional groups to develop their properties is one of the hot topics of research. In this context, we have investigated the properties of functionalized GQDs/p-type Si diode in this study. Polyethylenimine (PEI) functionalized nitrogen-doped GQDs (PEI/N/GQDs) have been successfully produced by the hydrothermal method. Afterward, we fabricated the Al/PEI/N/GQDs/p-Si diode. The parameters of GQDs-based Schottky diode have been investigated from current-voltage (I-V) measurements at 300 K. The barrier heights (Φb) of the diode obtained from Thermionic Emission (TE) theory, Norde’s, and Cheung’s approaches are 0.76 eV, 0.82 eV, and 0.66 eV, respectively. The ratio of rectification (RR) of the diode has been calculated to be approximately 2.8 × 104 at ± 5 V. In addition, the surface state density (Nss) versus (Ess-Ev) profile of the diode has been also obtained, by taking into account the voltage dependence of the ideality factor (n) and Φb. The average value of them has been found as 1.90 × 1013 eV−1cm−2, which is very suitable for this structure. The obtained results show that the prepared Al/PEI/N/GQDs/p-Si has Schottky diode behavior.

Self-Reverse-Blocking Control of Dual-Gate Monolithic Bidirectional GaN Switch With Quasi-Ohmic on-State Characteristic

Converter topologies such as current-source rectifiers and inverters require switching devices with bipolar voltage blocking and unidirectional current conduction capability. Recently available dual-gate GaN monolithic bidirectional switches (MBDSs) can mimic such self-reverse-blocking (SRB) behavior if the MBDS’ two gates are controlled accordingly, but thus need twice the number of gate signals and gate drive circuits. Therefore, we propose cascode-diode control (i.e., without additional sensing or gate drive circuitry) of one MBDS gate using a cascode configuration with a low-voltage silicon Schottky diode. The resulting SRB-MBDS features quasi-ohmic conduction characteristic and single-gate control. We provide static and dynamic measurements of a discrete proof-of-concept realization (600-V, 190-m <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mathrm{\Omega }$</tex-math></inline-formula> GaN MBDS; 40-V, 10-A silicon Schottky diode) that demonstrate the proposed SRB-MBDS’ feasibility.

Investigation of structural, kinetics and electrical properties of CuAlMnZn shape memory alloy – p-type silicon Schottky diode

SEM (scanning electron microscopy) and DSC (differential scanning calorimetry) measurements were done to characterize the microstructure and transformation temperature properties of the materials. The CuAlMnZn shape memory alloy (SMA) was used as a Schottky contact in Schottky diode fabricating. The electrical behavior of the diode was investigated using current and admittance experiments. Current-voltage (I–V), capacitance-voltage (C–V) and conductivity voltage (G/ω-V) measurements of the produced diode were carried out at room temperature, dark, light and at different frequencies. For the diode we obtained, basic diode parameters such as ideality factor (n), barrier height (Φb), shunt resistance (Rsh) and series resistance (Rs) were calculated. The current-voltage (I–V) measurements showed that the produced diode exhibits a good rectification in dark conditions. The frequency and potential dependence of the C–V and G/ω-V characteristics of this diod were investigated. It was observed that the C–V and G/ω-V characteristics changed significantly with frequency. The increase in capacitance, especially at low frequencies, was attributed to the presence of interfacial states at the metal/semiconductor interface. The Rsh and Rs values were observed to decrease with illumination. The experimental observations showed that the CuAlMnZn/p-Si Schottky diode can be used as a photodiode for optoelectronic applications.

Electrical properties of 3 MeV proton irradiated silicon Schottky diodes

This work presents the effects of proton irradiations on the electrical properties of n-silicon-based Schottky diodes. A change in electrical properties of the diodes due to 3 MeV proton irradiation to the fluence of 1017 ion cm−2 was investigated by current-voltage (I-V) and capacitance-voltage (C-V) techniques. A drastic decrease in forward current by a factor of 103 indicates a reduction of free injected effective carrier density in the space charge region. This reduction in the density is observed by a decrease in rectification ratio after proton irradiation. The results in general indicate that proton induced defects are responsible for the recombination/compensation of charge carriers resulting in an increase in the resistivity of the material. An increase in the resistivity is confirmed by high series resistance and low doping density evaluated on the irradiated diode. A change in dominated diode conduction mechanism due to irradiation presented here is of technological importance. Furthermore, the results presented here would, certainly, contribute to an ongoing study on the induced damage by radiation in silicon.

High-Power Wire Bonded GaN Rectifier for Wireless Power Transmission

A novel wire bonded GaN rectifier for high-power wireless power transfer (WPT) applications is proposed. The low breakdown voltage in silicon Schottky diodes limits the high-power operations of microwave rectifier. The proposed microwave rectifier consists of a high breakdown voltage GaN rectifying element for high-power operation and a novel low loss impedance matching technique for high efficiency performance. Wire bonding method is adopted to provide electrical connection between GaN chip and board which induces undesirable inductance. In order to realize high efficiency performance, an impedance matching network is proposed to exploit the unavoidable inductance along with a single shunt capacitor, resulting in a low loss matching circuit to achieve a compact high-power rectifier. The fabricated GaN rectifier exhibits a good performance in the high-power region and can withstand up to 39 dBm input power before reaching the breakdown limit at the operating frequency of 0.915 GHz and load resistance of 100 Ω. It has a compact size and exhibits high efficiency performance in high-power region (achieved a maximum efficiency of 61.2% at 39 dBm), making it suitable for high-power applications like future unmanned intelligent devices and WPT in space applications.

Time-Spectral based Polarization-Encoding for Spatial-Temporal Super-Resolved NSOM Readout

Detection of evanescent waves through Near-field Scanning Optical Microscopy (NSOM) has been simulated in the past, using Finite Elements Method (FEM) and 2D advanced simulations of a silicon Schottky diode, shaped as a truncated trapezoid photodetector, and sharing a subwavelength pin hole aperture. Towards enhanced resolution and next applications, the study of polarization’s influence was added to the scanning. The detector has been horizontally shifted across a vertically oriented Gaussian beam while several E-field modes, are projected on the top of the device. Both electrical and electro-optical simulations have been conducted. These results are promising towards the fabrication of a new generation of photodetector devices which can serve for Time-Spectral based Polarization-Encoding for Spatial-Temporal Super-Resolved NSOM Readout, as developed in the study.

Single Events Induced By Heavy Ions and Laser Pulses in Silicon Schottky Diodes

This paper is dedicated to the investigation of single-event effects (SEEs) in different types of silicon Schottky diodes using heavy ions and laser pulses. The objectives are both to progress in heavy ions and laser correlations using simple devices and to further understand the impact of optical and electrical parameters on photogeneration in Schottky diodes to contribute to the use of pulsed lasers for single-event sensitivity studies. Heavy ion test results on planar and trenched commercial Schottky diodes are presented. Based on these results, pulsed laser tests and transient measurements were performed on the sensitive devices. Destructive single events were evidenced with both techniques. Significant parameters of the laser tests, such as backside aperture of the device, electrical and optical configuration are discussed. These investigations show the potential of laser testing for Schottky diode SEE sensitivity study.

Minority Carrier Injection in High-Barrier Si-Schottky Diodes

In this paper, we investigate the presence of minority carriers and their role in charge carrier transport in silicon (Si) Schottky diodes with a high potential barrier. Using TCAD simulations along with an analytical model, we show that an inversion charge is induced at the metal–semiconductor (MS) interface in a high-barrier Schottky diode which imparts bipolar-type current characteristics to otherwise a unipolar Schottky diode, even at low-injection operation. In such a high-barrier diode, minority diffusion also becomes important along with the majority carrier thermionic emission and therefore cannot be neglected, unlike in a conventional Schottky diode. The presence of minority carriers at low injection in a high-barrier Si Schottky diode has been experimentally verified via a prior-reported two-diode electrical test method, reverse recovery measurements, and by measuring infrared electroluminescence. It is also shown, via TCAD simulations, that the diffusion component becomes more pronounced in case of a reduced Gummel number and at elevated temperatures.

V2O5/4H-SiC Schottky Diode Temperature Sensor: Experiments and Model

Performances of temperature sensors based on Divanadium Pentoxide/4H polytype of silicon carbide, V2O5/4H-SiC, and Schottky diodes are analyzed. The devices with an active area of $1.96\times 10^{-3}$ cm2 were characterized in a temperature range between 147.22 and 396.75 K and in a current range between $1~\mu \text{A}$ and 1 mA. Measurements reveal that at a bias current of $16~\mu \text{A}$ , the diode forward voltage shows a linear dependence on the temperature, with a sensitivity of 1.86 mV/K and a temperature error of 0.64 K. Sensors have also shown a good repeatability of sensing over more cycles of measurements in the considered temperature range. Numerical simulations are performed, and device physical parameters are obtained from the best fit with experimental data. From simulation results, we show that the conduction mechanism of the sensor is affected by traps at the V2O5/4H-SiC interface, which have been modeled with an exponential tail. Moreover, device parameters, as epilayer doping concentration and thickness, have been varied in order to evaluate the variations on the sensor performances.

Towards substrate engineering of graphene-silicon Schottky diode photodetectors.

Graphene-silicon Schottky diode photodetectors possess beneficial properties such as high responsivities and detectivities, broad spectral wavelength operation and high operating speeds. Various routes and architectures have been employed in the past to fabricate devices. Devices are commonly based on the removal of the silicon-oxide layer on the surface of silicon by wet-etching before deposition of graphene on top of silicon to form the graphene-silicon Schottky junction. In this work, we systematically investigate the influence of the interfacial oxide layer, the fabrication technique employed and the silicon substrate on the light detection capabilities of graphene-silicon Schottky diode photodetectors. The properties of devices are investigated over a broad wavelength range from near-UV to short-/mid-infrared radiation, radiation intensities covering over five orders of magnitude as well as the suitability of devices for high speed operation. Results show that the interfacial layer, depending on the required application, is in fact beneficial to enhance the photodetection properties of such devices. Further, we demonstrate the influence of the silicon substrate on the spectral response and operating speed. Fabricated devices operate over a broad spectral wavelength range from the near-UV to the short-/mid-infrared (thermal) wavelength regime, exhibit high photovoltage responses approaching 106 V W-1 and short rise- and fall-times of tens of nanoseconds.

Electro-optical study of nanoscale Al-Si-truncated conical photodetector with subwavelength aperture

A type of silicon photodiode has been designed and simulated to probe the optical near field and detect evanescent waves. These waves convey subwavelength resolution. This photodiode consists of a truncated conical shaped, silicon Schottky diode having a subwavelength aperture of 150 nm. Electrical and electro-optical simulations have been conducted. These results are promising toward the fabrication of a new generation of photodetector devices.

Graphene–Silicon Schottky Diodes for Photodetection

We present the optoelectronic characterization of two graphene/silicon Schottky junctions, fabricated by transferring CVD-graphene on flat and nanotip-patterned n-Si substrates, respectively. We demonstrate record photo responsivity, exceeding 2.5 A/W under white light, which we attribute to the contribution of charges photogenerated in the surrounding region of the flat junction or to the internal gain by impact ionization caused by the enhanced field on the nanotips.

Criterion for the Stability Against Thermal Runaway During Blocking Operation and Its Application to SiC Diodes

Silicon-Schottky diodes are well known for their poor blocking behavior at high temperatures and high blocking voltages. This behavior is particularly problematic, because the high leakage currents [1] lead to self-heating, which increases the leakage further. Due to this fatal feedback loop, a thermal runaway [2] may occur. Silicon carbide (SiC) devices are supposed to show much lower leakage current levels and a better thermal stability. However, early SiC-Schottky diodes were affected by nonideal leakage current densities [3] – [5] and, therefore, seriously threatened by thermal runaway as well. In this paper, the blocking stability of commercial SiC-Schottky and SiC-p-i-n diodes is investigated. Due to different leakage mechanisms in SiC-Schottky and SiC-p-i-n diodes, both the device types show different voltage and temperature dependences of the leakage current. Nevertheless, the derived stability criterion (SC) is a reasonable approximation for both the diode types. In agreement with the SC, experimental results prove that thermal stability is reached during high-temperature operation and even under worst cooling conditions. Within the specified operating range, thermal runaway is, thus, no longer a limiting factor. However, the risk of a thermal runaway has to be reassessed when going to higher voltage, higher operating temperatures, and less cooling as promised by the SiC devices.

High Efficiency DC/AC/DC Converter Based on Synchronous Rectifier for Proton Exchange Membrane Fuel Cells

AbstractThis paper deals with the efficiency improvement of a DC/AC/DC converter used for proton exchange membrane fuel cell (PEMFC) coupling to an electrical vehicle DC bus. The power converter is based on a MOSFET inverter stage, a high frequency planar technology transformer stage and a full bridge diode rectifier output stage. The diode rectifier is a source of losses due to the diode forward voltage, which may be reduced by implementation of synchronous rectifier technology, especially for high output current. Mosfets with low drain‐to‐source on‐resistance are coupled to the diodes to reduce the losses. Control principle of this converter is presented with losses modeling and efficiency study in order to highlight the advantages of the synchronous rectification. Efficiency improvement is quantified from a comparison study with technological choices including silicon carbide (SiC) MOSFET and Schottky diodes. This study points out that the synchronous rectification becomes really relevant for an actual scale‐1 application and not for our reduced scale laboratory power converter. Finally, experimental validation of the control is presented with our laboratory test bench. The realization of a scale‐1 converter is under study to experimentally validate the advantages of the proposed synchronous rectification.

Schottky Diode Derating for Survivability in a Heavy Ion Environment

In this paper, we irradiate a number of silicon power Schottky diodes from a variety of manufacturers. The tested diodes represent a wide assortment of reverse voltages and forward currents. Additionally, we review correlations between single-event failures in Schottky diodes and device electrical parameters. The spatial locations of failures in the diode are discussed, as well as a possible explanation for why the failures occur. Based on these correlations to date, we propose a derating scheme for Schottky diodes flown in a heavy ion environment and suggest screening procedures for decreasing the risks of such failures.

Effects of Surface Passivation and Annealing on Electrical Characteristics of Graphene/&lt;I&gt;n&lt;/I&gt;-type Silicon Schottky Diodes

Effects of Surface Passivation and Annealing on Electrical Characteristics of Graphene/&lt;I&gt;n&lt;/I&gt;-type Silicon Schottky Diodes

Paralleled Three-Phase Current-Source Rectifiers for High-Efficiency Power Supply Applications

This paper presents the paralleling operation of three-phase current-source rectifiers (CSRs) as the front-end power conversion stage of data center power supply systems based on 400- $\hbox{V}_{\rm dc} $ power delivery architecture, which has been proven to have higher efficiency than traditional ac architectures. A control algorithm of paralleled three-phase CSRs is introduced to achieve balanced outputs and individual rectifier module hot swap, which are required by power supply systems. By using silicon carbide (SiC) power semiconductors, SiC MOSFETs, and Schottky diodes, the power losses of the front-end stage are reduced, and the power supply system efficiency can be further increased. The prototype of a 19-kW front-end rectifier to convert 480 $\hbox{V}_{{\rm ac},{\rm rms}}$ to 400 $\hbox{V}_{\rm dc} $ , based on three paralleled three-phase CSRs, is developed. Each CSR is an all-SiC converter and designed for high efficiency, and the front-end stage full-load efficiency is greater than 98% from experimental tests. The balanced outputs and individual converter hot swap are realized in the hardware prototype too.

Contact Effect on the Current–Voltage Characteristic of Graphene Nanoribbon Based Schottky Diode

This paper presents the study of the current-voltage characteristic of graphene nanoribbon based Schottky diode using analytical method. The work presents a simple model to analyse the current-voltage characteristic in the function of Schottky barrier properties such as the potential barrier and the Schottky barrier lowering effect of graphene nanoribbon contact. Thermionic emission effect and tunneling effect were considered in the development of the current-voltage characteristic. By using the analytical method, the analytical model for potential barrier, Schottky barrier lowering effect and the current-voltage characteristic of graphene nanoribbon Schottky diode are presented. Based on the obtained result, it is found that the potential barrier has a quadratic relationship relative to its depletion region width. Besides that, the Schottky barrier lowering effect is dependent on the applied voltage. Both of these two parameters, the potential barrier and the Schottky barrier lowering effect are temperature dependent. The presented current-voltage model was compared with silicon Schottky diode and germanium Schottky diode which shows different contact effect when different metal and semiconductor were used for Schottky contact. Moreover a comparison study between the presented model with experimental graphene Schottky diode shows that the presented model indicates similar leaning of the current-voltage characteristic with experimental work.

Study of the relaxation of the excess current in silicon Schottky diodes

This study is devoted to investigation of the relaxation of excess current in silicon α-NiTi-n-Si Schottky diodes subjected to either γ-ray radiation or local disturbance of the interface structure using a diamond indenter. A decrease in the excess diode current is attained using both thermal annealing and ultra-sound irradiation. Simultaneously, the parameters of solar cells manufactured from the above-mentioned Schottky diodes subjected to irradiation with γ-ray photons and to single or double irradiation with ultra-sound are studied. It is shown that, after the effect of the diamond indenter, the excess current decreases as a result of thermal annealing; however, a decrease in the excess current to the initial value is not attained. The photoelectric parameters of the studied solar cells before irradiation and after irradiation with γ-ray photons and after single or double irradiation with ultrasound show that ultrasonic treatment is more efficient than thermal annealing.