Showing papers on "Schottky diode published in 2016"
TL;DR: A review of the state-of-the art of the research on graphene/semiconductor junctions, the attempts towards a modeling and the most promising applications can be found in this article.
348 citations
TL;DR: This review investigates the experimental efforts in interfacing 2D layers with 3D materials and analyzes the properties of the heterojunctions formed between them, calling for careful reconsideration of the physical models describing the junction behavior.
Abstract: After a decade of intensive research on two-dimensional (2D) materials inspired by the discovery of graphene, the field of 2D electronics has reached a stage with booming materials and device architectures. However, the efficient integration of 2D functional layers with three-dimensional (3D) systems remains a significant challenge, limiting device performance and circuit design. In this review, we investigate the experimental efforts in interfacing 2D layers with 3D materials and analyze the properties of the heterojunctions formed between them. The contact resistivity of metal on graphene and related 2D materials deserves special attention, while the Schottky junctions formed between metal/2D semiconductor or graphene/3D semiconductor call for careful reconsideration of the physical models describing the junction behavior. The combination of 2D and 3D semiconductors presents a form of p–n junctions that have just marked their debut. For each type of the heterojunctions, the potential applications are re...
310 citations
TL;DR: An on-chip integrated metal graphene–silicon plasmonic Schottky photodetector with 85 mA/W responsivity at 1.55 μm and 7% internal quantum efficiency is reported, paving the way to graphene integrated silicon photonics.
Abstract: We report an on-chip integrated metal graphene–silicon plasmonic Schottky photodetector with 85 mA/W responsivity at 1.55 μm and 7% internal quantum efficiency. This is one order of magnitude higher than metal–silicon Schottky photodetectors operated in the same conditions. At a reverse bias of 3 V, we achieve avalanche multiplication, with 0.37A/W responsivity and avalanche photogain ∼2. This paves the way to graphene integrated silicon photonics.
279 citations
TL;DR: In this paper, the temperature-dependent electrical properties of Pt/Ga2O3 Schottky barrier diodes (SBDs) fabricated on n−-Ga 2O3 drift layers grown on single-crystal n+-G 2O 3 (001) substrates by halide vapor phase epitaxy were investigated.
Abstract: We investigated the temperature-dependent electrical properties of Pt/Ga2O3 Schottky barrier diodes (SBDs) fabricated on n–-Ga2O3 drift layers grown on single-crystal n+-Ga2O3 (001) substrates by halide vapor phase epitaxy. In an operating temperature range from 21 °C to 200 °C, the Pt/Ga2O3 (001) Schottky contact exhibited a zero-bias barrier height of 1.09–1.15 eV with a constant near-unity ideality factor. The current–voltage characteristics of the SBDs were well-modeled by thermionic emission in the forward regime and thermionic field emission in the reverse regime over the entire temperature range.
251 citations
TL;DR: In this paper, the authors report switching performance of a new 1700-V, 50-A SiC MOSFET designed and developed by Cree, Inc. and compare it with other SiC devices.
Abstract: Due to wider band gap of silicon carbide (SiC) compared to silicon (Si), MOSFET made in SiC has considerably lower drift region resistance, which is a significant resistive component in high-voltage power devices. With low on-state resistance and its inherently low switching loss, SiC MOSFETs can offer much improved efficiency and compact size for the converter compared to those using Si devices. In this paper, we report switching performance of a new 1700-V, 50-A SiC MOSFET designed and developed by Cree, Inc. Hard-switching losses of the SiC MOSFETs with different circuit parameters and operating conditions are measured and compared with the 1700-V Si BiMOSFET and 1700-V Si IGBT, using same test set-up. Based on switching and conduction losses, the operating boundary of output power and switching frequency of these devices are found out in a dc–dc boost converter and compared. The switching $dv/dts$ and $di/dts$ of SiC MOSFET are captured and discussed in the perspective of converter design. To validate the continuous operation, three dc–dc boost converters using these devices, are designed and tested at 10 kW of power with 1 kV of output voltage and 10 kHz of switching frequency. 1700-V SiC Schottky diode is used as the blocking diode in each case. Corresponding converter efficiencies are evaluated and the junction temperature of each device is estimated. To demonstrate high switching frequency operation, the SiC MOSFET is switched upto 150 kHz within permissible junction temperature rise. A switch combination of the 1700-V SiC MOSFET and 1700-V SiC Schottky diode connected in series is also evaluated for zero voltage switching turn-ON behavior and compared with those of bipolar Si devices. Results show substantial power loss saving with the use of SiC MOSFET.
242 citations
TL;DR: N nanoscale magnetic tunnel junction microwave detectors are demonstrated, exhibiting high-detection sensitivity of 75,400’mV mW−1 at room temperature without any external bias fields, and for low-input power (micro-Watts or lower).
Abstract: Microwave detectors based on the spin-torque diode effect are among the key emerging spintronic devices By utilizing the spin of electrons in addition to charge, they have the potential to overcome the theoretical performance limits of their semiconductor (Schottky) counterparts However, so far, practical implementations of spin-diode microwave detectors have been limited by the necessity to apply a magnetic field Here, we demonstrate nanoscale magnetic tunnel junction microwave detectors, exhibiting high-detection sensitivity of 75,400 mV mW(-1) at room temperature without any external bias fields, and for low-input power (micro-Watts or lower) This sensitivity is significantly larger than both state-of-the-art Schottky diode detectors and existing spintronic diodes Micromagnetic simulations and measurements reveal the essential role of injection locking to achieve this sensitivity performance This mechanism may provide a pathway to enable further performance improvement of spin-torque diode microwave detectors
153 citations
TL;DR: Schottky barrier heights of metal-MoS2 contacts to devices fabricated from CVD synthesized MoS2 films were reduced by inserting a thin tunneling Ta2O5 layer between MoS 2 and metal contacts to directly correlate with exponential reductions in contact resistance.
Abstract: Creating high-quality, low-resistance contacts is essential for the development of electronic applications using two-dimensional (2D) layered materials. Many previously reported methods for lowering the contact resistance rely on volatile chemistry that either oxidize or degrade in ambient air. Nearly all reported efforts have been conducted on only a few devices with mechanically exfoliated flakes which is not amenable to large scale manufacturing. In this work, Schottky barrier heights of metal-MoS2 contacts to devices fabricated from CVD synthesized MoS2 films were reduced by inserting a thin tunneling Ta2O5 layer between MoS2 and metal contacts. Schottky barrier height reductions directly correlate with exponential reductions in contact resistance. Over two hundred devices were tested and contact resistances extracted for large scale statistical analysis. As compared to metal-MoS2 Schottky contacts without an insulator layer, the specific contact resistivity has been lowered by up to 3 orders of magni...
142 citations
TL;DR: In this paper, a self-trapped hole formation near the Schottky barrier in reverse bias was found to produce photoconductive gain, which can explain the operation of a variety of β-Ga2O3 photodetectors.
Abstract: Solar-blind photodetection and photoconductive gain >50 corresponding to a responsivity >8 A/W were observed for β-Ga2O3 Schottky photodiodes. The origin of photoconductive gain was investigated. Current-voltage characteristics of the diodes did not indicate avalanche breakdown, which excludes carrier multiplication by impact ionization as the source for gain. However, photocapacitance measurements indicated a mechanism for hole localization for above-band gap illumination, suggesting self-trapped hole formation. Comparison of photoconductivity and photocapacitance spectra indicated that self-trapped hole formation coincides with the strong photoconductive gain. It is concluded that self-trapped hole formation near the Schottky diode lowers the effective Schottky barrier in reverse bias, producing photoconductive gain. Ascribing photoconductive gain to an inherent property like self-trapping of holes can explain the operation of a variety of β-Ga2O3 photodetectors.
141 citations
29 Nov 2016
TL;DR: In this article, the authors demonstrate tunable Schottky barrier height and record photo-responsivity in a new concept device made of a single-layer CVD graphene transferred onto a matrix of nanotips patterned on n-type Si wafer.
Abstract: We demonstrate tunable Schottky barrier height and record photo-responsivity in a new-concept device made of a single-layer CVD graphene transferred onto a matrix of nanotips patterned on n-type Si wafer. The original layout, where nano-sized graphene/Si heterojunctions alternate to graphene areas exposed to the electric field of the Si substrate, which acts both as diode cathode and transistor gate, results in a two-terminal barristor with single-bias control of the Schottky barrier. The nanotip patterning favors light absorption, and the enhancement of the electric field at the tip apex improves photo-charge separation and enables internal gain by impact ionization. These features render the device a photodetector with responsivity (3 A/W for white LED light at 3 mW/cm2 intensity) almost an order of magnitude higher than commercial photodiodes. We extensively characterize the voltage and the temperature dependence of the device parameters and prove that the multi-junction approach does not add extra-inhomogeneity to the Schottky barrier height distribution. This work represents a significant advance in the realization of graphene/Si Schottky devices for optoelectronic applications.
129 citations
TL;DR: In this paper, the physical properties of Schottky-junctions formed on hybrid perovskite CH3NH3PbBr3 single crystals were investigated and a photodetectivity of 1.4 × 1010 Jones was obtained at zero bias, which increases to 7.1 × 1011 Jones at a bias of +3 V.
Abstract: Schottky junctions formed between semiconductors and metal contacts are ubiquitous in modern electronic and optoelectronic devices. Here we report on the physical properties of Schottky-junctions formed on hybrid perovskite CH3NH3PbBr3 single crystals. It is found that light illumination can significantly increase the dielectric constant of perovskite junctions by 2300%. Furthermore, such Pt/perovskite junctions are used to fabricate self-biased photodetectors. A photodetectivity of 1.4 × 1010 Jones is obtained at zero bias, which increases to 7.1 × 1011 Jones at a bias of +3 V, and the photodetectivity remains almost constant in a wide range of light intensity. These devices also exhibit fast responses with a rising time of 70 μs and a falling time of 150 μs. As a result of the high crystal quality and low defect density, such single-crystal photodetectors show stable performance after storage in air for over 45 days. Our results suggest that hybrid perovskite single crystals provide a new platform to develop promising optoelectronic applications.
125 citations
TL;DR: In this paper, the authors used MoS 2 /GaAs heterojunction as a self-driven photodetector with wide response band width from ultraviolet to visible light, which exhibits high sensitivity to the incident light of 635 nm.
TL;DR: In this article, the carbon doping effect on SBD performance was studied by adjusting the growth conditions and spanning carbon doping concentration between ≤3.5 µm and 3.9 µm.
Abstract: Vertical GaN Schottky barrier diode (SBD) structures were grown by metal-organic chemical vapor deposition on free-standing GaN substrates. The carbon doping effect on SBD performance was studied by adjusting the growth conditions and spanning the carbon doping concentration between ≤3 × 1015 cm−3 and 3 × 1019 cm−3. Using the optimized growth conditions that resulted in the lowest carbon incorporation, a vertical GaN SBD with a 6-μm drift layer was fabricated. A low turn-on voltage of 0.77 V with a breakdown voltage over 800 V was obtained from the device.
TL;DR: In this paper, the authors demonstrate tunable Schottky barrier height and record photo-responsivity in a new concept device made of a single-layer CVD graphene transferred onto a matrix of nanotips patterned on n-type Si wafer.
Abstract: We demonstrate tunable Schottky barrier height and record photo-responsivity in a new-concept device made of a single-layer CVD graphene transferred onto a matrix of nanotips patterned on n-type Si wafer. The original layout, where nano-sized graphene/Si heterojunctions alternate to graphene areas exposed to the electric field of the Si substrate, which acts both as diode cathode and transistor gate, results in a two-terminal barristor with single-bias control of the Schottky barrier. The nanotip patterning favors light absorption, and the enhancement of the electric field at the tip apex improves photo-charge separation and enables internal gain by impact ionization. These features render the device a photodetector with responsivity (3 A/W for white LED light at 3 mW/cm2 intensity) almost an order of magnitude higher than commercial photodiodes. We extensively characterize the voltage and the temperature dependence of the device parameters and prove that the multi-junction approach does not add extra-inhomogeneity to the Schottky barrier height distribution. This work represents a significant advance in the realization of graphene/Si Schottky devices for optoelectronic applications.
TL;DR: Interestingly, GQD sensitized nanorod-based device demonstrated high EQE value of 13,161% at -1 V bias (wavelength ∼340 nm), which is eight times higher than pristine ZnO NR-based detector, which revealed high external quantum efficiency (EQE) more than 100%.
Abstract: Graphene quantum dot (GQD)-sensitized ZnO nanorods/poly(3,4-ethylenedioxythiophene) polystyrenesulfonate (PEDOT:PSS) Schottky junction has been fabricated for visible-blind ultraviolet (UV) photodetector applications. Schottky diode parameters such as ideality factor, effective work function, and series resistance have been studied for GQD-modified and pristine ZnO nanorod-based devices. Under illumination of broadband light of intensity 80 mW/cm2, GQD-sensitized samples showed 11 times higher photocurrent value compared to pristine ZnO at −0.75 V external bias. GQD-modified detector demonstrated maximum photocurrent at UV region (wavelength ∼340 nm) for all reverse bias voltages. ZnO nanorods/polymer Schottky junction UV detectors revealed high external quantum efficiency (EQE) more than 100%. Interestingly, GQD sensitized nanorod-based device demonstrated high EQE value of 13,161% at −1 V bias (wavelength ∼340 nm), which is eight times higher than pristine ZnO NR-based detector. GQD-modified detectors a...
TL;DR: The important role of interfacial energetics played in photoelectrochemical conversion is identified and an unprecedentedly low onset potential of 0.9 V (vs RHE) is realized for water oxidation among n-Si photoanodes.
Abstract: The photoanodes with heterojunction behavior could enable the development of solar energy conversion, but their performance largely suffers from the poor charge separation and transport process through the multiple interfacial energy levels involved. The question is how to efficiently manipulate these energy levels. Taking the n-Si Schottky photoanode as a prototype, the undesired donor-like interfacial defects and its adverse effects on charge transfer in n-Si/ITO photoanode are well recognized and diminished through the treatment on electronic energy level. The obtained n-Si/TiOx/ITO Schottky junction exhibits a highly efficient charge transport and a barrier height of 0.95 eV, which is close to the theoretical optimum for n-Si/ITO Schottky contact. Then, the holes extraction can be further facilitated through the variation of surface energy level, with the NiOOH coated ITO layer. This is confirmed by a 115% increase in surface photovoltage of the photoanodes. Eventually, an unprecedentedly low onset po...
TL;DR: In this paper, first-principles calculations are performed to investigate the effects of interlayer coupling and the electric field on the electronic structures of graphene and molybdenum disulphide (MoS2) monolayers in two-dimensional ultrathin graphene and MoS2 heterostructures.
Abstract: Combining the electronic structures of graphene and molybdenum disulphide (MoS2) monolayers in two-dimensional (2D) ultrathin graphene and MoS2 heterostructures has been realized experimentally for novel nanoelectronic devices. Here, first-principles calculations are performed to investigate the effects of interlayer coupling and the electric field on the electronic structures of graphene and MoS2 heterobilayers (G/MoS2 HBLs). We find that an n-type Schottky contact is formed at the G/MoS2 interface with a small Schottky barrier of 0.23 eV, because the work function of graphene is close to the electron affinity of MoS2. Furthermore, increasing the interfacial distances between graphene and MoS2 can reduce the n-type Schottky barriers at the G/MoS2 interface. But applying the electric field perpendicular to the G/MoS2 HBL can not only control the Schottky barriers but also the Schottky contacts (n-type and p-type) and Ohmic contacts (n-type) at the G/MoS2 interface. Tunable p-type doping in graphene is easily achieved at negative electric fields because electrons can easily transfer from the Dirac point of graphene to the conduction band of MoS2.
TL;DR: The effectiveness of common techniques of mitigating shoot-through, including bipolar gate drives, multiple gate resistance switching paths, and external gate-source and snubber capacitors, has been evaluated for both technologies at different temperatures and switching rates and shows that solutions are less effective for SiC-MOSFETs.
Abstract: The temperature and $dV/dt$ dependence of crosstalk has been analyzed for Si-IGBT and SiC-MOSFET power modules. Due to a smaller Miller capacitance resulting from a smaller die area, the SiC module exhibits smaller shoot-through currents compared with similarly rated Si-IGBT modules in spite of switching with a higher $dV/dt$ and with a lower threshold voltage. However, due to high voltage overshoots and ringing from the SiC Schottky diode, SiC modules exhibit higher shoot-through energy density and induce voltage oscillations in the dc link. Measurements show that the shoot-through current exhibits a positive temperature coefficient for both technologies, the magnitude of which is higher for the Si-IGBT, i.e., the shoot-through current and energy show better temperature stability in the SiC power module. The effectiveness of common techniques of mitigating shoot-through, including bipolar gate drives, multiple gate resistance switching paths, and external gate–source and snubber capacitors, has been evaluated for both technologies at different temperatures and switching rates. The results show that solutions are less effective for SiC-MOSFETs because of lower threshold voltages and smaller margins for negative gate bias on the SiC-MOSFET gate. Models for evaluating the parasitic voltage have also been developed for diagnostic and predictive purposes. These results are important for converter designers seeking to use SiC technology.
TL;DR: In this article, the structural stability and electronic properties of monolayer and bilayer graphene with SnS hybrid heterostructures were studied by using the first-principle methods.
TL;DR: The first transport measurements evidencing the formation of a MoS2 Schottky barrier (SB) junction with barrier height of 0.13-0.18 eV are reported, revealing unique device fingerprint of SB-based field-effect transistors made from atom-thin 1T layers.
Abstract: Among atomically thin two-dimensional (2D) materials, molybdenum disulfide (MoS2) is attracting considerable attention because of its direct bandgap in the 2H-semiconducting phase. On the other hand, a 1T-metallic phase has been revealed, bringing complementary application. Recently, thanks to top-down fabrication using electron beam (EB) irradiation techniques, in-plane 1T-metal/2H-semiconductor lateral (Schottky) MoS2 junctions were demonstrated, opening a path toward the co-integration of active and passive two-dimensional devices. Here, we report the first transport measurements evidencing the formation of a MoS2 Schottky barrier (SB) junction with barrier height of 0.13–0.18 eV created at the interface between EB-irradiated (1T)/nonirradiated (2H) regions. Our experimental findings, supported by state-of-the-art simulation, reveal unique device fingerprint of SB-based field-effect transistors made from atom-thin 1T layers.
TL;DR: In this article, the impact of surface roughness after the recessed-anode formation on device characteristics is investigated, and an improved surface condition can reduce the leakage current and enhance the breakdown voltage simultaneously.
Abstract: In this letter, we demonstrate high-performance AlGaN/GaN Schottky barrier diodes (SBDs) on Si substrate with a recessed-anode structure for reduced turn-on voltage $V_{\mathrm {ON}}$ . The impact of the surface roughness after the recessed-anode formation on device characteristics is investigated. An improved surface condition can reduce the leakage current and enhance the breakdown voltage simultaneously. A low turn-on voltage of only 0.73 V can be obtained with a 50-nm recess depth. In addition, the different lengths of Schottky extension acting like a field plate are investigated. A high reverse breakdown voltage of 2070 V and a low specific ON-resistance of 3.8 $\text{m}\Omega \cdot \textrm {cm}^{2}$ yield an excellent Baliga’s figure of merit of 1127 MW/cm2, which can be attributed to the low surface roughness of only 0.6 nm and also a proper Schottky extension of 2 $\mu \text{m}$ to alleviate the peak electric field intensity in the SBDs.
TL;DR: Amorphous zinc oxide based resistive random access memory (RRAM) Ag/a-ZnO/Pt devices were fabricated and their resistive switching characteristics investigated as discussed by the authors.
Abstract: Amorphous zinc oxide (a-ZnO) based resistive random access memory (RRAM) Ag/a-ZnO/Pt devices were fabricated and their resistive switching characteristics investigated. The Ag/a-ZnO/Pt RRAMs exhibit typical bipolar resistive switching features with the resistance ratio of high to low resistance states (HRS/LRS) more than 107. Detailed current–voltage I–V characteristic analysis suggests that the conduction mechanism in the low resistance state is due to the formation of metallic filaments. Schottky emission is proven to be the dominant conduction mechanism in the high resistance state which results from the Schottky contacts between the metal electrodes and ZnO. The Ag/a-ZnO/Pt devices also show excellent retention performance. These results suggest promising application potentials for Ag/a-ZnO/Pt RRAMs.
TL;DR: A field-effect device based on dual graphene-GaSe heterojunctions is demonstrated that exhibits strong rectification with tunable threshold voltage and detailed theoretical modeling is used to explain the device operation.
Abstract: A field-effect device based on dual graphene-GaSe heterojunctions is demonstrated. Monolayer graphene is used as electrodes on a GaSe channel to form two opposing Schottky diodes controllable by local top gates. The device exhibits strong rectification with tunable threshold voltage. Detailed theoretical modeling is used to explain the device operation and to distinguish the differences compared to a single diode.
TL;DR: In this paper, the authors reported a new 900 V 4H-SiC JBSFET with an integrated JBS diode in the center area of the chip, which resulted in 30% reduction in SiC wafer area consumption in case of 10 A rating device.
Abstract: This letter reports a new 900 V 4H-SiC JBSFET containing an MOSFET with an integrated JBS diode in the center area of the chip. Both MOSFET and JBS diode structures utilize the same edge termination structure,which results in 30% reduction in SiC wafer area consumption in case of 10 A rating device. In order to form a Schottky contact for the JBS diode as well as ohmic contacts for n+ source and p+ body of the MOSFET,a simple metal process flow has been newly developed. It was found that Ni can simultaneously form ohmic contacts on n+ and p+ implanted regions while it remains a Schottky contact on the n-epitaxial drift layer when it is annealed at moderate temperature (900°C for 2 min). The proposed JBSFET was successfully fabricated using a nine-mask on 6-in 4H-SiC wafers.
TL;DR: In this paper, the authors investigated the light sensing behavior and also discussed the induced charge transport phenomena through the junction made by aluminium and hydrothermally derived zinc-sulfide (ZnS).
Abstract: In this report we have investigated the light sensing behavior and also discussed the induced charge transport phenomena through the junction made by aluminium and hydrothermally derived zinc-sulfide (ZnS). In this regards the structural, optical and electrical characterization of ZnS was performed well. The optical band gap energy (=3.68 eV) estimated from optical spectra and room temperature conductivity (0.49 × 10−6 S cm−1) measured from current–voltage characteristic explores the inorganic semiconductor behavior of the synthesized material. Depending upon the work function, aluminium (=4.4 eV) was preferred as metal contact to develop a potential barrier within the junction to study the underneath mechanism of charge transport through metal/inorganic-semiconductor interface. Moreover we have fabricated the sandwich structure ITO/ZnS/Al junction to study the effect of incident light on charge transport phenomena and demonstrated the potential applicability of the synthesized material to over crown the research on inorganic nano-semiconductor. The everbound charge transport phenomena within the device was analyzed by thermoionic emission theory. In searching its performance within light sensing electronic device we have deliberated the mobility-lifetime product, diffusion length and density of states (DOS) near Fermi level very aptly.
TL;DR: A scheme for a new type of spintronics-based high-frequency detector based on the expulsion of the vortex core in a magnetic tunnel junction, independent of the incoming RF current amplitude, offering a fast real-time RF threshold detector.
Abstract: It has been proposed that high-frequency detectors based on the so-called spin-torque diode effect in spin transfer oscillators could eventually replace conventional Schottky diodes due to their nanoscale size, frequency tunability and large output sensitivity. Although a promising candidate for information and communications technology applications, the output voltage generated from this effect has still to be improved and, more pertinently, reduces drastically with decreasing radiofrequency (RF) current. Here we present a scheme for a new type of spintronics-based high-frequency detector based on the expulsion of the vortex core in a magnetic tunnel junction (MTJ). The resonant expulsion of the core leads to a large and sharp change in resistance associated with the difference in magnetoresistance between the vortex ground state and the final C-state configuration. Interestingly, this reversible effect is independent of the incoming RF current amplitude, offering a fast real-time RF threshold detector.
TL;DR: In this paper, a two-level voltage source converter (2L-VSC) using SiC MOSFETs and Si IGBTs is presented, which is operated to supply 35 kVA load at 20-kHz switching frequency with dc bus voltage of 800 V and corresponding experimental results are presented.
Abstract: Silicon carbide (SiC) MOSFET is capable of achieving better efficiency and better power density of power converters due to its low on-state resistance and lower switching losses compared to silicon (Si) Insulated Gate Bipolar Transistor. Operation of power converters at higher switching frequency using SiC devices allows reduction in filter size and hence improves the power to weight ratio of the converter. This paper presents switching characterization of 1200-V 100-A SiC MOSFET module and compares the efficiency of a two-level voltage source converter (2L-VSC) using SiC MOSFETs and Si IGBTs. Also, various design considerations of the 1200-V 100-A SiC MOSFET-based 2L-VSC including gate drive design, bus bar packaging, and thermal management have been elaborated. The designed and developed 2L-VSC is operated to supply 35 kVA load at 20-kHz switching frequency with dc bus voltage of 800 V and the corresponding experimental results are presented.
TL;DR: Using ab initio energy band calculations and more reliable ab-in-time quantum transport simulations, this paper studied the interfacial properties of ML MoSe2-metal interfaces (metals = Al, Ag, Pt, Cr, Ni, and Ti).
Abstract: Monolayer (ML) transition-metal dichalcogenides are considered as promising channel materials in next-generation transistors. Using ab initio energy band calculations and more reliable ab initio quantum transport simulations, we study the interfacial properties of ML MoSe2–metal interfaces (metals = Al, Ag, Pt, Cr, Ni, and Ti). Weak or medium adsorption is found between ML MoSe2 and the Al, Ag, and Pt surfaces with the band structure of ML MoSe2 preserved, while strong adsorption is found between ML MoSe2 and the Ni, Ti, and Cr surfaces with the band structure of ML MoSe2 destroyed. The two methods give similar polarity and height of Schottky barriers for ML MoSe2 with Al, Ag, Pt, and Ti electrodes. ML MoSe2 forms an n-type Schottky contact with Ag, Ti, and Al electrodes with electron Schottky barrier heights (SBH) of 0.25, 0.29, and 0.56 eV, respectively, and a p-type Schottky contact with Pt electrode with hole SBH of 0.78 eV according to ab initio quantum transport simulations. Our study offers a guida...
TL;DR: In this paper, the optical properties of two-dimensional Schottky photodiode heterojunctions made of chemical vapor deposited (CVD) graphene on n- and p-type silicon (Si) substrates were studied.
Abstract: We have studied the optical properties of two-dimensional (2D) Schottky photodiode heterojunctions made of chemical vapor deposited (CVD) graphene on n- and p-type silicon (Si) substrates. Much better rectification behavior is observed from the diodes fabricated on n-Si substrates in comparison with the devices on p-Si substrates in dark condition. Also, graphene – n-Si photodiodes show a considerable responsivity of 270 mA W −1 within the silicon spectral range in DC reverse bias condition. The present results are furthermore compared with that of a molybdenum disulfide (MoS 2 ) – p-type silicon photodiode.
TL;DR: In this article, a state-of-the-art 520-620 GHz receiver front end working at room temperature was designed, built, and measured, and the receiver front-end features a GaAs-Schottky diode-based subharmonic mixer and a 260-307 GHz doubler.
Abstract: A state-of-the-art 520-620-GHz receiver front end working at room temperature was designed, built, and measured. The receiver front-end features a GaAs-Schottky diode-based subharmonic mixer and a 260-307-GHz doubler, both fabricated with the new LERMA-LPN Schottky process on a 4- μm-thick GaAs membrane suspended in a waveguide with metal beamleads. Small-area mesas and optimized transmission lines with low dielectric loading are used. At 295 K ambient temperature, an average of 1284 K DSB receiver noise temperature was measured over the 520-620-GHz frequency range, including the 3.5-8.5-GHz IF chain loss. A record 1130 K minimum DSB receiver noise temperature at 557 GHz was measured. At 134 K ambient temperature, an average DSB receiver noise temperature of 685 K from 538 to 600 GHz was measured when correcting for the cryostat window loss. A minimum DSB receiver noise of 585 K was measured at an RF center frequency of 540 GHz. The 520-620-GHz receiver presented in this article allows an increase in the sensitivity of the JUpiter ICy Moons Explrorer-SWI instrument of about a factor of two compared with requirements. It will allow study of the Jovian system with particular emphasis on the chemistry, meteorology, structure, and atmospheric coupling processes of Jupiter and its icy satellites, thereby providing important data for the exploration of their habitable zones.
TL;DR: It is shown how modulation of the Schottky barriers at drain and source by a separate gate can enable the selection of the carriers injected in the channel, and achieved controllable polarity behaviour with ON/OFF current ratios >106 for both electrons and holes conduction.
Abstract: As scaling of conventional silicon-based electronics is reaching its ultimate limit, considerable effort has been devoted to find new materials and new device concepts that could ultimately outperform standard silicon transistors. In this perspective two-dimensional transition metal dichalcogenides, such as MoS2 and WSe2, have recently attracted considerable interest thanks to their electrical properties. Here, we report the first experimental demonstration of a doping-free, polarity-controllable device fabricated on few-layer WSe2. We show how modulation of the Schottky barriers at drain and source by a separate gate, named program gate, can enable the selection of the carriers injected in the channel, and achieved controllable polarity behaviour with ON/OFF current ratios >106 for both electrons and holes conduction. Polarity-controlled WSe2 transistors enable the design of compact logic gates, leading to higher computational densities in 2D-flatronics.