Showing papers on "Schottky diode published in 2015"
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.
Abstract: In the past decade graphene has been one of the most studied material for several unique and excellent properties. Due to its two dimensional nature, physical and chemical properties and ease of manipulation, graphene offers the possibility of integration with the exiting semiconductor technology for next-generation electronic and sensing devices. In this context, the understanding of the graphene/semiconductor interface is of great importance since it can constitute a versatile standalone device as well as the building-block of more advanced electronic systems. Since graphene was brought to the attention of the scientific community in 2004, the device research has been focused on the more complex graphene transistors, while the graphene/semiconductor junction, despite its importance, has started to be the subject of systematic investigation only recently. As a result, a thorough understanding of the physics and the potentialities of this device is still missing. The studies of the past few years have demonstrated that graphene can form junctions with 3D or 2D semiconducting materials which have rectifying characteristics and behave as excellent Schottky diodes. The main novelty of these devices is the tunable Schottky barrier height, a feature which makes the graphene/semiconductor junction a great platform for the study of interface transport mechanisms as well as for applications in photo-detection, high-speed communications, solar cells, chemical and biological sensing, etc. In this paper, we review the state-of-the art of the research on graphene/semiconductor junctions, the attempts towards a modeling and the most promising applications.
409 citations
TL;DR: In this paper, the state-of-the-art of In2O3 in terms of semiconductor applications is summarized, with the focus on the charge carrier transport properties of the material.
Abstract: The present review takes a semiconductor physics perspective to summarize the state-of-the art of In2O3 in relation to applications. After discussing conventional and novel applications, the crystal structure, synthesis of single-crystalline material, band-structure and optical transparency are briefly introduced before focussing on the charge carrier transport properties. The issues of unintentional n-type conductivity and its likely causes, the surface electron accumulation, and the lack of p-type conductivity will be presented. Intentional doping will be demonstrated to control the electron concentration and resistivity over a wide range, but is also subject to compensation. The control of the surface accumulation in relation to Schottky and ohmic contacts will be demonstrated. In the context of scattering mechanisms, the electron mobility and its limits will be discussed. Finally, the Seebeck coefficient and its significance will be shown, and ferromagnetic doping of In2O3 will be critically discussed. With this overview most if not all ingredients for the use of In2O3 as semiconductor material in novel or improved conventional devices will be given.
231 citations
TL;DR: In this paper, the authors reviewed the mechanism focusing on how Schottky barrier and SPR phenomena help to improve a photoreaction, as well as the paradox between the SBS and SPR in the matter of the direction of electron flow in the metal/semiconductor system.
222 citations
TL;DR: In this paper, the authors reviewed the most exciting recent progress in interface engineering for improving the channel mobility and fundamental understanding of channel transport in 4H-SiC power metal oxide Semiconductor Field Effect Transistors.
Abstract: A sustainable energy future requires power electronics that can enable significantly higher efficiencies in the generation, distribution, and usage of electrical energy. Silicon carbide (4H-SiC) is one of the most technologically advanced wide bandgap semiconductor that can outperform conventional silicon in terms of power handling, maximum operating temperature, and power conversion efficiency in power modules. While SiC Schottky diode is a mature technology, SiC power Metal Oxide Semiconductor Field Effect Transistors are relatively novel and there is large room for performance improvement. Specifically, major initiatives are under way to improve the inversion channel mobility and gate oxide stability in order to further reduce the on-resistance and enhance the gate reliability. Both problems relate to the defects near the SiO2/SiC interface, which have been the focus of intensive studies for more than a decade. Here we review research on the SiC MOS physics and technology, including its brief history, the state-of-art, and the latest progress in this field. We focus on the two main scientific problems, namely, low channel mobility and bias temperature instability. The possible mechanisms behind these issues are discussed at the device physics level as well as the atomic scale, with the support of published physical analysis and theoretical studies results. Some of the most exciting recent progress in interface engineering for improving the channel mobility and fundamental understanding of channel transport is reviewed.
220 citations
TL;DR: Multilayered graphene and single-layered graphene are assembled onto perovskite films in the form of Schottky junctions and ohmic contacts, respectively, for the production of a graphene-based hole transporting material-free perovSKite solar cell.
Abstract: Multilayered graphene and single-layered graphene are assembled onto perovskite films in the form of Schottky junctions and ohmic contacts, respectively, for the production of a graphene-based hole transporting material-free perovskite solar cell. Multilayered graphene extracts charge selectively and efficiently, delivering a higher efficiency of 11.5% than single-layered graphene (6.7%).
218 citations
TL;DR: In this article, a gated graphene/semiconductor van der Waals Schottky diode was used for high efficient solar cell with power conversion efficiency of 18.5% and open circuit voltage of 0.96V.
176 citations
TL;DR: The fabrication and device characteristics of exfoliated, few-layer, dual-gated ReS2 field effect transistors (FETs) demonstrate current saturation, voltage gain, and a subthreshold swing of 148 mV/decade.
Abstract: We report the fabrication and device characteristics of exfoliated, few-layer, dual-gated ReS2 field effect transistors (FETs). The ReS2 FETs display n-type behavior with a room temperature Ion/Ioff of 105. Many devices were studied with a maximum intrinsic mobility of 12 cm2·V–1·s–1 at room temperature and 26 cm2·V–1·s–1 at 77 K. The Cr/Au-ReS2 contact resistance determined using the transfer length method is gate-bias dependent and ranges from 175 kΩ·μm to 5 kΩ·μm, and shows an exponential dependence on back-gate voltage indicating Schottky barriers at the source and drain contacts. Dual-gated ReS2 FETs demonstrate current saturation, voltage gain, and a subthreshold swing of 148 mV/decade.
175 citations
TL;DR: In this article, a novel fuel cell device based on integrating the Schottky junction effect with the electrochemical principle is designed, constructed, and verified through experiments, and it is found that it is possible to use Schott...
Abstract: A novel fuel cell device based on integrating the Schottky junction effect with the electrochemical principle is designed, constructed, and verified through experiments. It is found that the Schott ...
155 citations
TL;DR: The findings enable the best optimized flexible diodes to reach 6.3 GHz at zero bias, which is beyond the critical benchmark speed of 2.45 GHz to satisfy the principal frequency bands of smart phones such as those for cellular communication, Bluetooth, Wi-Fi and global satellite positioning.
Abstract: Mechanically flexible mobile phones have been long anticipated due to the rapid development of thin-film electronics in the last couple of decades. However, to date, no such phone has been developed, largely due to a lack of flexible electronic components that are fast enough for the required wireless communications, in particular the speed-demanding front-end rectifiers. Here Schottky diodes based on amorphous indium-gallium-zinc-oxide (IGZO) are fabricated on flexible plastic substrates. Using suitable radio-frequency mesa structures, a range of IGZO thicknesses and diode sizes have been studied. The results have revealed an unexpected dependence of the diode speed on the IGZO thickness. The findings enable the best optimized flexible diodes to reach 6.3 GHz at zero bias, which is beyond the critical benchmark speed of 2.45 GHz to satisfy the principal frequency bands of smart phones such as those for cellular communication, Bluetooth, Wi-Fi and global satellite positioning.
149 citations
TL;DR: A simple modelling approach is proposed to quantitatively describe the transfer characteristics of Schottky barrier-MOSFETs from ultra-thin body materials accurately in the device off-state and successfully applied the approach to extract Schotky barrier heights for electrons and holes in black phosphorus devices for a large range of body thicknesses.
Abstract: Owing to the difficulties associated with substitutional doping of low-dimensional nanomaterials, most field-effect transistors built from carbon nanotubes, two-dimensional crystals and other low-dimensional channels are Schottky barrier MOSFETs (metal-oxide-semiconductor field-effect transistors). The transmission through a Schottky barrier-MOSFET is dominated by the gate-dependent transmission through the Schottky barriers at the metal-to-channel interfaces. This makes the use of conventional transistor models highly inappropriate and has lead researchers in the past frequently to extract incorrect intrinsic properties, for example, mobility, for many novel nanomaterials. Here we propose a simple modelling approach to quantitatively describe the transfer characteristics of Schottky barrier-MOSFETs from ultra-thin body materials accurately in the device off-state. In particular, after validating the model through the analysis of a set of ultra-thin silicon field-effect transistor data, we have successfully applied our approach to extract Schottky barrier heights for electrons and holes in black phosphorus devices for a large range of body thicknesses.
145 citations
TL;DR: The presented work clearly shows that PEDOT:PSS forms a hybrid heterojunction with n-Si behaving similar to a conventional pn-junction and not, like commonly assumed, a Schottky junction.
Abstract: We investigated hybrid inorganic-organic solar cells combining monocrystalline n-type silicon (n-Si) and a highly conductive polymer poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS). The build-in potential, photo- and dark saturation current at this hybrid interface are monitored for varying n-Si doping concentrations. We corroborate that a high build-in potential forms at the hybrid junction leading to strong inversion of the n-Si surface. By extracting work function and valence band edge of the polymer from ultraviolet photoelectron spectroscopy, a band diagram of the hybrid n-Si/PEDOT:PSS heterojunction is presented. The current-voltage characteristics were analyzed using Schottky and abrupt pn-junction models. The magnitude as well as the dependence of dark saturation current on n-Si doping concentration proves that the transport is governed by diffusion of minority charge carriers in the n-Si and not by thermionic emission of majorities over a Schottky barrier. This leads to a comprehensive explanation of the high observed open-circuit voltages of up to 634 mV connected to high conversion efficiency of almost 14%, even for simple planar device structures without antireflection coating or optimized contacts. The presented work clearly shows that PEDOT:PSS forms a hybrid heterojunction with n-Si behaving similar to a conventional pn-junction and not, like commonly assumed, a Schottky junction.
TL;DR: In this article, an advanced edge termination technology has been developed by combining plasma treatment, tetramethylammonium hydroxide wet etching, and ion implantation to suppress the leakage along the etch sidewall.
Abstract: Conventional GaN vertical devices, though promising for high-power applications, need expensive GaN substrates. Recently, low-cost GaN-on-Si vertical diodes have been demonstrated for the first time. This paper presents a systematic study to understand and control the OFF-state leakage current in the GaN-on-Si vertical diodes. Various leakage sources were investigated and separated, including leakage through the bulk drift region, passivation layer, etch sidewall, and transition layers. To suppress the leakage along the etch sidewall, an advanced edge termination technology has been developed by combining plasma treatment, tetramethylammonium hydroxide wet etching, and ion implantation. With this advanced edge termination technology, an OFF-state leakage current similar to Si, SiC, and GaN lateral devices has been achieved in the GaN-on-Si vertical diodes with over 300 V breakdown voltage and 2.9-MV/cm peak electric field. The origin of the remaining OFF-state leakage current can be explained by a combination of electron tunneling at the p-GaN/drift-layer interface and carrier hopping between dislocation traps. The low leakage current achieved in these devices demonstrates the great potential of the GaN-on-Si vertical device as a new low-cost candidate for high-performance power electronics.
TL;DR: It is found that the SBHs without defects are quite strongly pinned, with a pinning factor S of about S = 0.3, a similar value for both top and edge contact geometries, despite the weak interlayer bonding in the isolated materials.
Abstract: The transition metal dichalcogenides (TMDs) are two-dimensional layered solids with van der Waals bonding between layers. We calculate their Schottky barrier heights (SBHs) using supercell models and density functional theory. It is found that the SBHs without defects are quite strongly pinned, with a pinning factor S of about S = 0.3, a similar value for both top and edge contact geometries. This arises because there is direct bonding between the contact metal atoms and the TMD chalcogen atoms, for both top and edge contact geometries, despite the weak interlayer bonding in the isolated materials. The Schottky barriers largely follow the metal induced gap state (MIGS) model, like those of three-dimensional semiconductors, despite the bonding in the TMDs being largely constrained within the layers. The pinning energies are found to be lower in the gap for edge contact geometries than for top contact geometries, which might be used to obtain p-type contacts on MoS2.
TL;DR: In this paper, the nonlinear characteristics of drain-source capacitance in SiC MOSFETs are studied in detail, and the simplified modeling methods for engineering applications are presented.
Abstract: The nonlinear junction capacitances of power devices are critical for the switching transient, which should be fully considered in the modeling and transient analysis, especially for high-frequency applications. The silicon carbide (SiC) MOSFET combined with SiC Schottky Barrier Diode (SBD) is recognized as the proposed choice for high-power and high-frequency converters. However, in the existing SiC MOSFET models only the nonlinearity of gate-drain capacitance is considered meticulously, but the drain–source capacitance, which affects the switching commutation process significantly, is generally regarded as constant. In addition, the nonlinearity of diode junction capacitance is neglected in some simplified analysis. Experiments show that without full consideration of nonlinear junction capacitances, some significant deviations between simulated and measured results will emerge in the switching waveforms. In this paper, the nonlinear characteristics of drain–source capacitance in SiC MOSFET are studied in detail, and the simplified modeling methods for engineering applications are presented. On this basis, the SiC MOSFET model is improved and the simulation results with improved model correspond with the measured results much better than before, which verify the analysis and modeling.
20 Apr 2015
TL;DR: In this article, the authors demonstrate a nanoscale broadband silicon plasmonic Schottky detector with high responsivity and improved signal to noise ratio operating in the sub-bandgap regime.
Abstract: We demonstrate a nanoscale broadband silicon plasmonic Schottky detector with high responsivity and improved signal to noise ratio operating in the sub-bandgap regime. Responsivity is enhanced by the use of pyramidally shaped plasmonic concentrators. Owing to the large cross-section of the pyramid, light is collected from a large area which corresponds to its base, concentrated toward the nano apex of the pyramid, absorbed in the metal, and generates hot electrons. Using the internal photoemission process, these electrons cross over the Schottky barrier and are collected as a photocurrent. The combination of using silicon technology together with the high collection efficiency and nanoscale confinement makes the silicon pyramids ideal for playing a central role in the construction of improved photodetectors. Furthermore, owing to the small active area, the dark current is significantly reduced as compared with flat detectors, and thus an improved signal to noise ratio is obtained. Our measurements show high responsivities over a broad spectral regime, with a record high of about 30 mA/W at the wavelength of 1064 nm, while keeping the dark current as low as ∼100 nA. Finally, such detectors can also be constructed in the form of a pixel array, and thus can be used as focal plane detector arrays.
TL;DR: In this article, an energy harvesting at 35 GHz has been developed, which known as a rectenna, an array of a rectangular microstrip patch antenna with 16 elements was used to efficiently convert RF to dc signal, and a step-impedance low-pass filter was used between the antenna and rectifier circuit to suppress second-order harmonic generated by the diode.
Abstract: In this letter, an energy harvester at 35 GHz has been developed, which known as a rectenna. An array of a rectangular microstrip patch antenna with 16 elements was used to efficiently convert RF to dc signal. A step-impedance low-pass filter is used between the antenna and rectifier circuit to suppress second-order harmonic generated by the diode. A GaAs Schottky diode MA4E1317 was used in parallel with load as a half-wave rectifier circuit. The fabrication process is based on conventional optical photolithography to obtain an integrated circuit. The maximum RF-to-dc conversion efficiency of 67% was successfully achieved with input RF power of 7 mW at 35.7 GHz.
TL;DR: In this paper, the forward characteristics of SiC p-i-n diodes are significantly improved by carrier-lifetime enhancement, and the differential on-resistance is inversely proportional to the square root of current density.
Abstract: Silicon carbide (SiC) p-i-n diodes having five different n−-layer ( $i$ -layer) thicknesses from 48 to $268~\mu $ m are fabricated. The forward characteristics of SiC p-i-n diodes are significantly improved by carrier-lifetime enhancement. After this improvement, the differential on-resistance is inversely proportional to the square root of current density for all the diodes with different thicknesses of n−-layer. As a result, the forward current density–voltage characteristics can be approximately expressed by a parabolic function, as in the case of Si p-i-n diodes. Using a 268- $\mu $ m-thick n−-layer, the lifetime enhancement, and an improved space-modulated junction termination extension structure, a very high blocking voltage over 26.9 kV and low differential on-resistance of 9.7 m $\Omega \cdot $ cm $^{2}$ are achieved.
TL;DR: It is demonstrated that time-resolved photoinduced reflectance from a semiconductor captures interfacial carrier dynamics and is critically important to solar-driven water splitting.
Abstract: Solar photoconversion in semiconductors is driven by charge separation at the interface of the semiconductor and contacting layers. Here we demonstrate that time-resolved photoinduced reflectance from a semiconductor captures interfacial carrier dynamics. We applied this transient photoreflectance method to study charge transfer at p-type gallium-indium phosphide (p-GaInP2) interfaces critically important to solar-driven water splitting. We monitored the formation and decay of transient electric fields that form upon photoexcitation within bare p-GaInP2, p-GaInP2/platinum (Pt), and p-GaInP2/amorphous titania (TiO2) interfaces. The data show that a field at both the p-GaInP2/Pt and p-GaInP2/TiO2 interfaces drives charge separation. Additionally, the charge recombination rate at the p-GaInP2/TiO2 interface is greatly reduced owing to its p-n nature, compared with the Schottky nature of the p-GaInP2/Pt interface.
TL;DR: It is proposed that Li vacancy hopping is the main diffusion mechanism in highly conductive Li3OCl, a prototypical LiRAP, using ab initio density functional theory (DFT) calculations and classical molecular dynamics simulations.
Abstract: Lithium-rich anti-perovskites (LiRAPs) are a promising family of solid electrolytes, which exhibit ionic conductivities above 10−3 S cm−1 at room temperature, among the highest reported values to date. In this work, we investigate the defect chemistry and the associated lithium transport in Li3OCl, a prototypical LiRAP, using ab initio density functional theory (DFT) calculations and classical molecular dynamics (MD) simulations. We studied three types of charge neutral defect pairs, namely the LiCl Schottky pair, the Li2O Schottky pair, and the Li interstitial with a substitutional defect of O on the Cl site. Among them the LiCl Schottky pair has the lowest binding energy and is the most energetically favorable for diffusion as computed by DFT. This is confirmed by classical MD simulations, where the computed Li ion diffusion coefficients for LiCl Schottky systems are significantly higher than those for the other two defects considered and the activation energy in LiCl deficient Li3OCl is comparable to experimental values. The high conductivities and low activation energies of LiCl Schottky systems are explained by the low energy pathways of Li between the Cl vacancies. We propose that Li vacancy hopping is the main diffusion mechanism in highly conductive Li3OCl.
TL;DR: In this article, the synthesis of novel zinc oxide with a lower defect density and its effect on the Al/ZnO Schottky junction has been demonstrated, and the defect density was estimated by positron annihilation lifetime measurement which ensures the material's superiority over the earlier reported results.
Abstract: In this report the synthesis of novel zinc oxide (ZnO) with a lower defect density and its effect on the Al/ZnO Schottky junction has been demonstrated. The defect density was estimated by positron annihilation lifetime measurement which ensures the material's superiority (i.e. free from point defects or any type of vacancies) over the earlier reported results. The thin film device of synthesized ZnO was fabricated on an ITO coated glass substrate. As the front contact was made by aluminium, the characteristic I–V produced rectifying Schottky behavior. The underlying charge transport mechanism through a metal–semiconductor (i.e. Al/ZnO) junction was analyzed on the basis of thermoionic emission theory to find out the quality of the fabricated device. In this regard we have studied the charge transport mechanism by measuring the density of states (DOS) at the Fermi level, mobility-lifetime product and diffusion length.
TL;DR: In this paper, a vertical GaN Schottky barrier diodes (SBDs) fabricated on a free-standing GaN substrate with different sizes of Schottkey electrode was reported.
Abstract: This paper reports on vertical GaN Schottky barrier diodes (SBDs) fabricated on a free-standing GaN substrate with different sizes of Schottky electrode. The fabricated SBDs with 3 ? 3 mm2 Schottky electrodes exhibited both a forward current of 50 A and a blocking voltage of 790 V. To our knowledge, the characteristics of operation with a simultaneous high forward current and high blocking voltage are reported for the first time for vertical GaN SBDs on free-standing GaN substrates. The dependence of these characteristics on the Schottky electrode size is also reported in detail.
TL;DR: It is found that the p-type MoS2 forms a Schottky junction with graphene with a barrier height of 139 meV, which results in high photocurrent and wide spectral range of detection with wavelength selectivity.
Abstract: Two dimensional (2D) Molybdenum disulfide (MoS2) has evolved as a promising material for next generation optoelectronic devices owing to its unique electrical and optical properties, such as band gap modulation, high optical absorption, and increased luminescence quantum yield. The 2D MoS2 photodetectors reported in the literature have presented low responsivity compared to silicon based photodetectors. In this study, we assembled atomically thin p-type MoS2 with graphene to form a MoS2/graphene Schottky photodetector where photo generated holes travel from graphene to MoS2 over the Schottky barrier under illumination. We found that the p-type MoS2 forms a Schottky junction with graphene with a barrier height of 139 meV, which results in high photocurrent and wide spectral range of detection with wavelength selectivity. The fabricated photodetector showed excellent photosensitivity with a maximum photo responsivity of 1.26 AW–1 and a noise equivalent power of 7.8 × 10–12 W/√Hz at 1440 nm.
TL;DR: This work examines the underlying physical mechanisms responsible for this RF-to-dc power conversion efficiency limitation, and explores a high I-V curvature backward tunnel diode to overcome this efficiency limitation.
Abstract: Harvesting low-density ambient microwave power as an alternative power source for small ubiquitous wireless nodes has been proposed in recent papers discussing emerging technologies like the Internet of Things and Smart Cities. However, a literature review of the state-of-the-art Schottky diode based microwave rectifiers shows that a maximum efficiency has been reached for such devices operating in the low-power regime, as is the case for ambient microwave power-harvesters. This work examines the underlying physical mechanisms responsible for this RF-to-dc power conversion efficiency limitation, and explores a high I-V curvature backward tunnel diode to overcome this efficiency limitation. Measurements of the 2.4 GHz RF-to-dc power conversion efficiency at $-$ 40 dBm input power demonstrates that the backward tunnel diode outperforms the HSMS-285B Schottky diode by a factor of 10.5 and the Skyworks SMS7630 by a factor of 5.5 in a lossless matching network scenario. A prototype built using a new GSG probe embedded with a matching circuit showed a total power conversion efficiency of 3.8% for $-$ 40 dBm input power and 18.2% for $-$ 30 dBm input power at 2.35 GHz.
TL;DR: In this article, an AlGaN/GaN-on-Si lateral power diode with recessed metal/Al2O3/III-nitride (MIS)-gated ohmic anode for improved forward conduction and reverse blocking has been realized.
Abstract: An AlGaN/GaN-on-Si lateral power diode with recessed metal/Al2O3/III-nitride (MIS)-gated ohmic anode for improved forward conduction and reverse blocking has been realized. The low onset voltage of $\sim 0.6$ V with good uniformity for the fabricated 189 devices is obtained. In comparison with the conventional Schottky diode the specific ON-resistance ( $R_{\mathrm {\mathbf {\mathrm{{\scriptscriptstyle ON}},SP}}})$ was reduced by 51% in a device with anode-to-cathode spacing ( $L_{\mathrm {\mathbf {AC}}})$ of 5 $\mu \text{m}$ . The incorporation of high- $k$ dielectric in the recessed gate region enabling two-order lower reverse leakage comparing with the conventional device, leading to a high breakdown voltage over 1.1 kV at leakage current as low as 10 $\mu \text{A}$ /mm in device with $L_{\mathrm {\mathbf {AC}}}=20~\mu \text{m}$ . The strong reverse blocking over 600 V was still achieved at 150 °C. The proposed diode is compatible with GaN normally $\mathbf {\mathrm{{\scriptstyle OFF}}}$ MIS high-electron-mobility transistors, revealing its potential for highly efficient GaN-on-Si power ICs.
TL;DR: In this article, the authors demonstrate the use of solution-processed Ga2O3 thin films (TFs) for electronic device applications and demonstrate that the rectification ratio and reverse breakdown voltage of typical SDs were $6 \times 10^{6}$ and 19.6 V, respectively.
Abstract: This paper demonstrates the use of cost-effective solution-processed $\alpha $ -Ga2O3 thin films (TFs) for electronic device applications. MESFETs based on AgO x Schottky diode (SD) gates were fabricated on highly crystalline Sn-doped $\alpha $ -Ga2O3 TFs, grown by mist chemical vapor deposition at atmospheric pressure and a substrate temperature of only 400 °C. The rectification ratio and reverse breakdown voltage of typical SDs were $6 \times 10^{6}$ and 19.6 V, respectively. The ON–OFF ratio of the corresponding transistors was $2 \times 10^{7}$ . The MESFETs that could withstand drain voltages of up to 48 V were also realized.
TL;DR: In this article, the tradeoff between the switching energy and electrothermal robustness is explored for 1.2kV SiC MOSFET, silicon power MOS-FET and 900-V CoolMOS body diodes at different temperatures.
Abstract: The tradeoff between the switching energy and electro-thermal robustness is explored for 1.2-kV SiC MOSFET, silicon power MOSFET, and 900-V CoolMOS body diodes at different temperatures. The maximum forward current for dynamic avalanche breakdown is decreased with increasing supply voltage and temperature for all technologies. The CoolMOS exhibited the largest latch-up current followed by the SiC MOSFET and silicon power MOSFET; however, when expressed as current density, the SiC MOSFET comes first followed by the CoolMOS and silicon power MOSFET. For the CoolMOS, the alternating p and n pillars of the superjunctions in the drift region suppress BJT latch-up during reverse recovery by minimizing lateral currents and providing low-resistance paths for carriers. Hence, the temperature dependence of the latch-up current for CoolMOS was the lowest. The switching energy of the CoolMOS body diode is the largest because of its superjunction architecture which means the drift region have higher doping, hence more reverse charge. In spite of having a higher thermal resistance, the SiC MOSFET has approximately the same latch-up current while exhibiting the lowest switching energy because of the least reverse charge. The silicon power MOSFET exhibits intermediate performance on switching energy with lowest dynamic latching current.
TL;DR: Permalloy (Py) contacts to both multilayer and monolayer MoS2 are investigated and a good tunability of the Schottky barrier height is achieved, which may pave the way to realize spin transport and spin injection inMoS2.
Abstract: MoS2 is a layered two-dimensional material with strong spin-orbit coupling and long spin lifetime, which is promising for electronic and spintronic applications. However, because of its large band gap and small electron affinity, a considerable Schottky barrier exists between MoS2 and contact metal, hindering the further study of spin transport and spin injection in MoS2. Although substantial progress has been made in improving device performance, the existence of metal-semiconductor Schottky barrier has not yet been fully understood. Here, we investigate permalloy (Py) contacts to both multilayer and monolayer MoS2. Ohmic contact is developed between multilayer MoS2 and Py electrodes with a negative Schottky barrier, which yields a high field-effect mobility exceeding 55 cm2V−1s−1 at low temperature. Further, by applying back gate voltage and inserting different thickness of Al2O3 layer between the metal and monolayer MoS2, we have achieved a good tunability of the Schottky barrier height (down to zero). These results are important in improving the performance of MoS2 transistor devices; and it may pave the way to realize spin transport and spin injection in MoS2.
TL;DR: In this paper, NiO-ZnO heterojunction is used for piezoelectric performance enhancement via both suppressing the screening effect in the ZnO film and forming a reliable p-n junction at the interfaces instead of the Schottky barriers.
TL;DR: An atomistic insight into potential barrier formation and band bending is provided by ab initio simulations and model analysis of a prototype Schottky diode, i.e., niobium doped rutile titania in contact with gold (Au/Nb:TiO2).
Abstract: The formation of a Schottky barrier at the metal-semiconductor interface is widely utilised in semiconductor devices. With the emerging of novel Schottky barrier based nanoelectronics, a further microscopic understanding of this interface is in high demand. Here we provide an atomistic insight into potential barrier formation and band bending by ab initio simulations and model analysis of a prototype Schottky diode, i.e., niobium doped rutile titania in contact with gold (Au/Nb:TiO2). The local Schottky barrier height is found to vary between 0 and 1.26 eV depending on the position of the dopant. The band bending is caused by a dopant induced dipole field between the interface and the dopant site, whereas the pristine Au/TiO2 interface does not show any band bending. These findings open the possibility for atomic scale optimisation of the Schottky barrier and light harvesting in metal-semiconductor nanostructures.
TL;DR: In this article, a nanoporous tungsten trioxide (WO3) Schottky diode-based gas sensor was developed by depositing a platinum (Pt) catalytic contact and tested towards hydrogen gas and ethanol vapour.
Abstract: This paper reports the development of nanoporous tungsten trioxide (WO3) Schottky diode-based gas sensors. Nanoporous WO3 films were prepared by anodic oxidation of tungsten foil in ethylene glycol mixed with ammonium fluoride and a small amount of water. Anodization resulted in highly ordered WO3 films with a large surface-to-volume ratio. Utilizing these nanoporous structures, Schottky diode-based gas sensors were developed by depositing a platinum (Pt) catalytic contact and tested towards hydrogen gas and ethanol vapour. Analysis of the current–voltage characteristics and dynamic responses of the sensors indicated that these devices exhibited a larger voltage shift in the presence of hydrogen gas compared to ethanol vapour at an optimum operating temperature of 200 °C. The gas sensing mechanism was discussed, associating the response to the intercalating H+ species that are generated as a result of hydrogen and ethanol molecule breakdowns onto the Pt/WO3 contact and their spill over into nanoporous WO3.