Showing papers on "Schottky barrier published in 2019"
TL;DR: In this article, an interfacial Schottky junction composed of Ti3C2 and porous g-C3N4 nanosheets (TC/pCN) is constructed by a facile electrostatic self-assembly route to significantly boost the spatial charge separation to promote the activation of molecular oxygen for H2O2 production.
Abstract: The development of efficient photocatalysts for the production of hydrogen peroxide (H2O2) is a promising strategy to realize solar-to-chemical energy conversion. Graphitic carbon nitride (g-C3N4) presents giant potential for photocatalytic H2O2 production, but the sluggish charge separation depresses its photocatalytic performance. Herein, an interfacial Schottky junction composed of Ti3C2 nanosheets and porous g-C3N4 nanosheets (TC/pCN) is constructed by a facile electrostatic self-assembly route to significantly boost the spatial charge separation to promote the activation of molecular oxygen for H2O2 production. As the optimal sample, TC/pCN-2 possesses the highest H2O2 production rate (2.20 μmol L−1 min−1) under visible light irradiation (λ > 420 nm), which is about 2.1 times than that of the porous g-C3N4. The results of superoxide radical detection and rotating disk electrode measurement suggest that the two-step single-electron reduction of oxygen is the predominant reaction step during this photocatalytic H2O2 production process. The enhanced photocatalytic performance is ascribed to the formation of Schottky junction and subsequent built-in electric field at their interface, which accelerate the spatial charge separation and restrain the charge recombination. This work provides an in-depth understanding of the mechanism of photocatalytic H2O2 production, and gives ideas for the design of highly active materials for photocatalytic H2O2 production.
427 citations
TL;DR: Results suggest that the present PdSe2/perovskite Schottky junction photodetectors may be useful for assembly of optoelectronic system applications in near future.
Abstract: Group-10 transition metal dichalcogenides (TMDs) with distinct optical and tunable electrical properties have exhibited great potential for various optoelectronic applications. Herein, a self-powered photodetector is developed with broadband response ranging from deep ultraviolet to near-infrared by combining FA1- x Cs x PbI3 perovskite with PdSe2 layer, a newly discovered TMDs material. Optoelectronic characterization reveals that the as-assembled PdSe2/perovskite Schottky junction is sensitive to light illumination ranging from 200 to 1550 nm, with the highest sensitivity centered at ≈800 nm. The device also shows a large on/off ratio of ≈104, a high responsivity (R) of 313 mA W-1, a decent specific detectivity (D*) of ≈1013 Jones, and a rapid response speed of 3.5/4 µs. These figures of merit are comparable with or much better than most of the previously reported perovskite detectors. In addition, the PdSe2/perovskite device exhibits obvious sensitivity to polarized light, with a polarization sensitivity of 6.04. Finally, the PdSe2/perovskite detector can readily record five "P," "O," "L," "Y," and "U" images sequentially produced by 808 nm. These results suggest that the present PdSe2/perovskite Schottky junction photodetectors may be useful for assembly of optoelectronic system applications in near future.
266 citations
TL;DR: The photoplasticity of the artificial synapse has been modulated by heterosynaptic means with a sub-1 V external voltage, not only enabling an optoelectronic analog of the mechanical aperture device showing adaptive and stable optical perception capability under different illuminating conditions but also making the artificialsynapse suitable for the mimicry of interest-modulated human visual memories.
Abstract: The rapid development of artificial intelligence techniques and future advanced robot systems sparks emergent demand on the accurate perception and understanding of the external environments via visual sensing systems that can co-locate the self-adaptive detecting, processing, and memorizing of optical signals. In this contribution, a simple indium–tin oxide/Nb-doped SrTiO3 (ITO/Nb:SrTiO3) heterojunction artificial optoelectronic synapse is proposed and demonstrated. Through the light and electric field co-modulation of the Schottky barrier profile at the ITO/Nb:SrTiO3 interface, the oxide heterojunction device can respond to the entire visible light region in a neuromorphic manner, allowing synaptic paired-pulse facilitation, short/long-term memory, and “learning-experience” behavior for optical information manipulation. More importantly, the photoplasticity of the artificial synapse has been modulated by heterosynaptic means with a sub-1 V external voltage, not only enabling an optoelectronic analog of ...
192 citations
TL;DR: A high-gain, fully inkjet-printed Schottky barrier organic thin-film transistor amplifier circuit that delivered gain near the theoretical limit at a power below 1 nanowatt and detected electrophysiological signals from the skin with a wearable device is reported.
Abstract: Overcoming the trade-offs among power consumption, fabrication cost, and signal amplification has been a long-standing issue for wearable electronics. We report a high-gain, fully inkjet-printed Schottky barrier organic thin-film transistor amplifier circuit. The transistor signal amplification efficiency is 38.2 siemens per ampere, which is near the theoretical thermionic limit, with an ultralow power consumption of 60 decibels and noise voltage of <0.3 microvolt per hertz1/2 at 100 hertz.
177 citations
TL;DR: In this paper, copper was deposited on as well as encapsulated in a semiconductor-like MOF to fabricate the Cu/Cu@UiO-66 catalyst via an advanced double-solvent approach followed by one-step reduction.
Abstract: Metal-organic framework (MOF) is one of the most promising porous materials in photocatalysis. In this study, copper was deposited on as well as encapsulated in a semiconductor-like MOF (UiO-66) to fabricate the Cu/Cu@UiO-66 catalyst via an advanced double-solvent approach followed by one-step reduction. Even with ultralow amount of copper, Cu/Cu@UiO-66 shows significantly enhanced photocatalytic activity as well as stability for partial oxidation of aromatic alcohols under visible light irradiation. The result is attributed to the integration of plasmonic effect (Cu nanoparticles on UiO-66) and Schottky junction (Cu quantum dots encapsulated in UiO-66) which can be considered as a promising noble-metal-free way for the enhancement of visible-light-driven photocatalytic activity of MOFs.
159 citations
TL;DR: This demonstration of contact interface engineering with CVD-grown MoS2 and graphene is a key step toward the practical application of atomically thin TMDC-based devices with low-resistance contacts for high-performance large-area electronics and optoelectronics.
Abstract: 2D transition metal dichalcogenides (TMDCs) have emerged as promising candidates for post-silicon nanoelectronics owing to their unique and outstanding semiconducting properties. However, contact engineering for these materials to create high-performance devices while adapting for large-area fabrication is still in its nascent stages. In this study, graphene/Ag contacts are introduced into MoS2 devices, for which a graphene film synthesized by chemical vapor deposition (CVD) is inserted between a CVD-grown MoS2 film and a Ag electrode as an interfacial layer. The MoS2 field-effect transistors with graphene/Ag contacts show improved electrical and photoelectrical properties, achieving a field-effect mobility of 35 cm2 V-1 s-1 , an on/off current ratio of 4 × 108 , and a photoresponsivity of 2160 A W-1 , compared to those of devices with conventional Ti/Au contacts. These improvements are attributed to the low work function of Ag and the tunability of graphene Fermi level; the n-doping of Ag in graphene decreases its Fermi level, thereby reducing the Schottky barrier height and contact resistance between the MoS2 and electrodes. This demonstration of contact interface engineering with CVD-grown MoS2 and graphene is a key step toward the practical application of atomically thin TMDC-based devices with low-resistance contacts for high-performance large-area electronics and optoelectronics.
147 citations
TL;DR: In this paper, a post-treatment technique via pulsed laser irradiation of CdS (L-CdS) semiconductor was developed to significantly enhance the visible light-driven hydrogen evolution performance from water splitting.
Abstract: Herein, we developed one simple and novel post-treatment technique via pulsed laser irradiation of CdS (L-CdS) semiconductor to significantly enhance the visible light-driven hydrogen evolution performance from water splitting, during which the rate of hydrogen evolution over L-CdS in the first hour is 40-times than that of pure CdS. Because the pulsed laser irradiation induces the in-situ formation of metallic Cd clusters on CdS surface to construct the Schottky junction between Cd clusters and CdS, obviously facilitating the electron transfer from excited CdS into Cd to endow more photogenerated electrons for enhancing the photocatalytic efficiency of H2 evolution. Moreover, the bandgap narrow of post-treated CdS also benefits the stronger light absorption for enhancing the photocatalytic efficiency. This work may provide a new approach to develop heterojunction-based photocatalysts for efficient solar-to-chemical conversion.
146 citations
TL;DR: This work employs density functional theory calculations to show that van der Waals stacking can significantly modulate Schottky barrier heights in the contact formed between multilayer InSe and 2D metals by suppressing the FLP effect.
Abstract: Incorporation of two-dimensional (2D) materials in electronic devices inevitably involves contact with metals, and the nature of this contact (Ohmic and/or Schottky) can dramatically affect the electronic properties of the assembly. Controlling these properties to reliably form low-resistance Ohmic contact remains a great challenge due to the strong Fermi level pinning (FLP) effect at the interface. Herein, we employ density functional theory calculations to show that van der Waals stacking can significantly modulate Schottky barrier heights in the contact formed between multilayer InSe and 2D metals by suppressing the FLP effect. Importantly, the increase of InSe layer number induces a transition from Schottky to Ohmic contact, which is attributed to the decrease of the conduction band minimum and rise of the valence band maximum of InSe. Based on the computed tunneling and Schottky barriers, Cd3C2 is the most compatible electrode for 2D InSe among the materials studied. This work illustrates a straightforward method for developing more effective InSe-based 2D electronic nanodevices.
146 citations
TL;DR: The eloquent evidences clearly prove that doping-adjusting the Fermi level has great potential applications in high-performance GaAs nanowire photodetectors and other functional photodETectors.
Abstract: Metal-semiconductor-metal (MSM)-structured GaAs-based nanowire photodetectors have been widely reported because they are promising as an alternative for high-performance devices. Owing to the Schottky built-in electric fields in the MSM structure photodetectors, enhancements in photoresponsivity can be realized. Thus, strengthening the built-in electric field is an efficacious way to make the detection capability better. In this study, we fabricate a single GaAs nanowire MSM photodetector with superior performance by doping-adjusting the Fermi level to strengthen the built-in electric field. An outstanding responsivity of 1175 A/W is obtained. This is two orders of magnitude better than the responsivity of the undoped sample. Scanning photocurrent mappings and simulations are performed to confirm that the enhancement in responsivity is because of the increase in the hole Schottky built-in electric field, which can separate and collect the photogenerated carriers more effectively. The eloquent evidence clearly proves that doping-adjusting the Fermi level has great potential applications in high-performance GaAs nanowire photodetectors and other functional photodetectors.
145 citations
TL;DR: In this paper, the small-angle beveled field plate (SABFP) was used to fabricate a very small bevel angle (∼ 1°) in the mesa and field plates.
Abstract: This letter demonstrates vertical Ga2O3 Schottky barrier diodes (SBDs) with a novel edge termination, the small-angle beveled field plate (SABFP), fabricated on thinned $\text{G}_{{2}}\text{O}_{{3}}$ substrates. Non-punch-though design is used for the drift region with a donor concentration of ${3}\sim {3.5} \times {10} ^{{16}}$ cm−3, rendering a device differential ON-resistance of $\sim 2~\text{m}\Omega ~\cdot $ cm2. A new wet-etch technique is developed by using a bi-layer mask, which consists of spin-on-glass (SOG) and plasma-enhanced chemical vapor deposited (PECVD) SiO2, to fabricate a very small bevel angle (∼ 1°) in the mesa and field plates. This SABFP structure facilitates the electric field spreading at device edges, rendering a breakdown voltage of 1100 V, a peak electric field of 3.5 MV/cm in Ga2O3 at the Schottky contact edge, and an averaged electric field over 3.4 MV/cm underneath the contact. Our device demonstrates a Baliga’s figure of merit of 0.6 GW/cm2, which is among the highest in all reported Ga2O3 power devices and comparable to the state-of-the-art GaN SBDs. These results show the great potential of Ga2O3 SBDs for future power applications.
131 citations
TL;DR: In this article, a cube-like CeO2 and ultrathin Ti3C2-MXene nanosheets were used as a two-dimensional platform via a simple hydrothermal route for the development of efficient photocatalysts for environmental remediation.
TL;DR: A Schottky-type heterostructure of Au-Bi2S3 with promising ability of reactive free radicals generation under X-ray irradiation for selectively enhancing radiotherapeutic efficacy by catalyzing intracellular H2O2 in tumor is developed.
Abstract: Despite the development of nanomaterials with high-Z elements for radiosensitizers, most of them suffer from their oxygen-dependent behavior in hypoxic tumor, nonideal selectivity to tumor, or inevasible damages to normal tissue, greatly limiting their further applications. Herein, we develop a Schottky-type heterostructure of Au–Bi2S3 with promising ability of reactive free radicals generation under X-ray irradiation for selectively enhancing radiotherapeutic efficacy by catalyzing intracellular H2O2 in tumor. On the one hand, like many other nanomaterials with rich high-Z elements, Au–Bi2S3 can deposit higher radiation dose within tumors in the form of high energy electrons. On the other hand, Au–Bi2S3 can remarkably improve the utilization of a large number of X-ray-induced low energy electrons during radiotherapy for nonoxygen dependent free radicals generation even in hypoxic condition. This feature of Schottky-type heterostructures Au–Bi2S3 attributes to the generated Schottky barrier between metal ...
TL;DR: It is presented evidence that metal-induced gap states (MIGS) are the origin for the large FLP similar to conventional semiconductors, and the origin of FLP in TMDC-based metal/semiconductor junctions is confirmed.
Abstract: Understanding the electron transport through transition-metal dichalcogenide (TMDC)-based semiconductor/metal junctions is vital for the realization of future TMDC-based (opto-)electronic devices. Despite the bonding in TMDCs being largely constrained within the layers, strong Fermi-level pinning (FLP) was observed in TMDC-based devices, reducing the tunability of the Schottky barrier height. We present evidence that metal-induced gap states (MIGS) are the origin for the large FLP similar to conventional semiconductors. A variety of TMDCs (MoSe2, WSe2, WS2, and MoTe2) were investigated using high-spatial-resolution surface characterization techniques, permitting us to distinguish between defected and pristine regions. The Schottky barrier heights on the pristine regions can be explained by MIGS, inducing partial FLP. The FLP strength is further enhanced by disorder-induced gap states induced by transition-metal vacancies or substitutionals at the defected regions. Our findings emphasize the importance of ...
01 Jan 2019
TL;DR: In this paper, thermal scanning probe lithography is used to pattern metal electrodes in direct contact with monolayer MoS2, creating field effect transistors that exhibit vanishing Schottky barrier heights, high on/off ratios of 1010, no hysteresis, and subthreshold swings as low as 64
Abstract: Two-dimensional semiconductors, such as molybdenum disulfide (MoS2), exhibit a variety of properties that could be useful in the development of novel electronic devices. However, nanopatterning metal electrodes on such atomic layers, which is typically achieved using electron beam lithography, is currently problematic, leading to non-ohmic contacts and high Schottky barriers. Here, we show that thermal scanning probe lithography can be used to pattern metal electrodes with high reproducibility, sub-10-nm resolution, and high throughput (105 μm2 h−1 per single probe). The approach, which offers simultaneous in situ imaging and patterning, does not require a vacuum, high energy, or charged beams, in contrast to electron beam lithography. Using this technique, we pattern metal electrodes in direct contact with monolayer MoS2 for top-gate and back-gate field-effect transistors. These devices exhibit vanishing Schottky barrier heights (around 0 meV), on/off ratios of 1010, no hysteresis, and subthreshold swings as low as 64 mV per decade without using negative capacitors or hetero-stacks. Thermal scanning probe lithography can be used to pattern metal electrodes in direct contact with monolayer MoS2, creating field-effect transistors that exhibit vanishing Schottky barrier heights, high on/off ratios of 1010, no hysteresis, and subthreshold swings as low as 64 mV per decade.
TL;DR: By simply spin-coating transparent Ti3 C2 -based MXene electrodes from aqueous suspensions onto GaAs patterned with a photoresist and lifted off with acetone, photodetectors that outperform more standard Au electrodes are fabricated.
Abstract: 2D transition metal carbides, known as MXenes, are transparent when the samples are thin enough. They are also excellent electrical conductors with metal-like carrier concentrations. Herein, these characteristics are exploited to replace gold (Au) in GaAs photodetectors. By simply spin-coating transparent Ti3 C2 -based MXene electrodes from aqueous suspensions onto GaAs patterned with a photoresist and lifted off with acetone, photodetectors that outperform more standard Au electrodes are fabricated. Both the Au- and MXene-based devices show rectifying contacts with comparable Schottky barrier heights and internal electric fields. The latter, however, exhibit significantly higher responsivities and quantum efficiencies, with similar dark currents, hence showing better dynamic range and detectivity, and similar sub-nanosecond response speeds compared to the Au-based devices. The simple fabrication process is readily integratable into microelectronic, photonic-integrated circuits and silicon photonics processes, with a wide range of applications from optical sensing to light detection and ranging and telecommunications.
TL;DR: A ligand-free and additive-free method was used to boost the basicity of the carbon supports and the acidity of Cu by increasing the Schottky barrier at their boundary, mimicking the beneficial function of organic ligands acting as the Lewis acid and base in metal-organic frameworks (MOFs) or polymers and simultaneously avoiding the possible deactivation associated with the necessary stability of a heterogeneous catalyst.
Abstract: Highly efficient fixation of CO2 for the synthesis of useful organic carbonates has drawn much attention. The design of sustainable Lewis acid-base pairs, which has mainly relied on expensive organic ligands, is the key challenge in the activation of the substrate and CO2 molecule. Here, we report the application of Mott-Schottky type nanohybrids composed of electron-deficient Cu and electron-rich N-doped carbon for CO2 fixation. A ligand-free and additive-free method was used to boost the basicity of the carbon supports and the acidity of Cu by increasing the Schottky barrier at their boundary, mimicking the beneficial function of organic ligands acting as the Lewis acid and base in metal-organic frameworks (MOFs) or polymers and simultaneously avoiding the possible deactivation associated with the necessary stability of a heterogeneous catalyst. The optimal Cu/NC-0.5 catalyst exhibited a remarkably high turnover frequency (TOF) value of 615 h-1 at 80 °C, which is 10 times higher than that of the state-of-the-art metal-based heterogeneous catalysts in the literature.
TL;DR: In this paper, the first observation of a gate-controlled field emission current from a tungsten diselenide (WSe2) monolayer, synthesized by chemical-vapour deposition on a SiO2/Si substrate, was reported.
Abstract: We report the first observation of a gate-controlled field emission current from a tungsten diselenide (WSe2) monolayer, synthesized by chemical-vapour deposition on a SiO2/Si substrate. Ni contacted WSe2 monolayer back-gated transistors, under high vacuum, exhibit n-type conduction and drain-bias dependent transfer characteristics, which are attributed to oxygen/water desorption and drain induced Schottky barrier lowering, respectively. The gate-tuned n-type conduction enables field emission, i.e. the extraction of electrons by quantum tunnelling, even from the flat part of the WSe2 monolayers. Electron emission occurs under an electric field ∼100 V μm-1 and exhibits good time stability. Remarkably, the field emission current can be modulated by the back-gate voltage. The first field-emission vertical transistor based on the WSe2 monolayer is thus demonstrated and can pave the way to further optimize new WSe2 based devices for use in vacuum electronics.
TL;DR: In this article, a self-powered and flexible ultraviolet photodetector based on the ZnO/Ag Schottky junction was designed and fabricated using a comprehensive pyro-phototronic effect, which can reach up to 1.25 mA W−1 for 325 nm illumination.
Abstract: As a coupling effect of pyroelectric and photoelectric effect, pyro-phototronic effect has demonstrated an excellent tuning role for fast response p–n junction photodetectors (PDs). Here, a comprehensive pyro-phototronic effect is utilized to design and fabricate a self-powered and flexible ultraviolet PD based on the ZnO/Ag Schottky junction. By using the primary pyroelectric effect, the maximal transient photoresponsivity of the self-powered PDs can reach up to 1.25 mA W−1 for 325 nm illumination, which is improved by 1465% relative to that obtained from the steady-state signal. The relative persistent secondary pyroelectric effect weakens the height of Schottky barrier, leading to a reduction of the steady-state photocurrent with an increase in the power density. When the power density is large enough, the steady-state photocurrent turns into a reverse direction. The corresponding tuning mechanisms of the comprehensive pyro-phototronic effect on transient and steady-state photocurrent are revealed based on the bandgap diagrams. The results may help us to further clarify the mechanism of the pyro-phototronic effect on the photocurrent and also provide a potential way to optimize the performance of self-powered PDs.
TL;DR: Improved sensitivity of a 2D MoS2-based gas sensor is demonstrated by controlling the Schottky barrier height and the NO2 responsivity increased, and it was found to be effective for CO and CO2 gases, which had little reactivity in 2DMoS2 -based gas sensors.
Abstract: Two-dimensional (2D) transition-metal dichalcogenides have attracted significant attention as gas-sensing materials owing to their superior responsivity at room temperature and their possible application as flexible electronic devices. Especially, reliable responsivity and selectivity for various environmentally harmful gases are the main requirements for the future chemiresistive-type gas sensor applications. In this study, we demonstrate improved sensitivity of a 2D MoS2-based gas sensor by controlling the Schottky barrier height. Chemical vapor deposition process was performed at low temperature to obtain layer-controlled 2D MoS2, and the NO2 gas responsivity was confirmed by the fabricated gas sensor. Then, the number of MoS2 layers was fixed and the types of electrode materials were varied for controlling the Schottky barrier height. As the Schottky barrier height increased, the NO2 responsivity increased, and it was found to be effective for CO and CO2 gases, which had little reactivity in 2D MoS2-b...
TL;DR: It was shown that the MIL-100(Fe)/Ti3C2 MXene composite not only has higher thermal stability but also has a significantly increased activity in nitrogen fixation under visible-light.
Abstract: A new microporous MIL-100(Fe)/Ti3C2 MXene composite was constructed as a non-noble metal-based Schottky junction photocatalyst with improved nitrogen fixation ability. Ti3C2 MXene nanosheets exhibited excellent metal conductivity and were employed as two-dimensional support to optimize the composite's energy band structure. MIL-100(Fe) with a large specific surface area was used as an adsorbent and a photocatalytic oxidation center. The MIL-100(Fe)/Ti3C2 MXene composite not only exhibited higher thermal stability but also showed significantly increased nitrogen fixation activity under visible light. The NO conversion rate of the composite catalyst was about four and three times higher than that of the pure Ti3C2 MXene and the pure MIL-100(Fe) samples, respectively. Although adsorption plays an important role in the nitrogen fixation process, the synergistic effects of the Schottky junctions are the main cause of the enhanced photocatalytic activity. The built-in electric field can be generated to form charge-transfer channels, which help to achieve a desirable photocatalytic activity.
TL;DR: In this article, the authors carried out a systematic investigation on gate degradation and the physical mechanism of the Schottky-type GAN gate HEMTs under positive gate voltage stress and found that the time-dependent gate degradation exhibits weak relevance with frequencies ranging from 10 to 100 kHz under dynamic gate stress.
Abstract: In this paper, we carried out a systematic investigation on gate degradation and the physical mechanism of the Schottky-type ${p}$ -GaN gate HEMTs under positive gate voltage stress. The frequency- and temperature-dependent measurements have been conducted. It is found that the time-dependent gate degradation exhibits weak relevance with frequencies ranging from 10 to 100 kHz under dynamic gate stress and is similar to that in static gate stress. Both the gate breakdown voltage (BV) and mean-time-to-failure (MTTF) show positive temperature dependence. Moreover, the current–voltage ( I–V ) characteristics and threshold voltage ( ${V}_{\text {TH}}$ ) instability of ${p}$ -GaN devices before/after gate degradation are compared and analyzed. The degraded Schottky junction exhibits an ohmic-like gate behavior. It is revealed that under a large gate bias stress, high-energy electrons accelerated in the depletion region of the ${p}$ -GaN layer would promote the formation of defect levels near the metal/ ${p}$ -GaN interface, leading to the initial ${p}$ -GaN layer degradation. The subsequent high gate leakage density could cause the final degradation of the AlGaN barrier.
TL;DR: In this paper, a biomimetic omnidirectional photon management scheme for ultrathin flexible graphene silicon Schottky junction solar cell is presented, which mimics the two essential light trapping mechanisms of a leaf.
TL;DR: It is shown that reducing the degree of van der Waals overlapping in all 2D ultrathin lateral devices composed of graphene:WS2:graphene leads to significant increase in photodetector responsivity, and the direct CVD growth reduces overlapping sections of WS2:Gr and leads to more uniform lateral systems.
Abstract: We show that reducing the degree of van der Waals overlapping in all 2D ultrathin lateral devices composed of graphene:WS2:graphene leads to significant increase in photodetector responsivity. This is achieved by directly growing WS2 using chemical vapor deposition (CVD) in prepatterned graphene gaps to create epitaxial interfaces. Direct-CVD-grown graphene:WS2:graphene lateral photodetecting transistors exhibit high photoresponsivities reaching 121 A/W under 2.7 × 105 mW/cm2 532 nm illumination, which is around 2 orders of magnitude higher than similar devices made by the layer-by-layer transfer method. The photoresponsivity of our direct-CVD-grown device shows negative correlation with illumination power under different gate voltages, which is different from similar devices made by the transfer method. We show that the high photoresponsivity is due to the lowering of effective Schottky barrier height by improving the contact between graphene and WS2. Furthermore, the direct CVD growth reduces overlapping sections of WS2:Gr and leads to more uniform lateral systems. This approach provides insights into scalable manufacturing of high-quality 2D lateral electronic and optoelectronic devices.
TL;DR: In this paper, the authors implemented Mg implanted edge termination (ET), a simple but very useful technique to increase the breakdown voltage (BV) of the vertical $\beta $ -Ga2O3 Schottky barrier diode (SBD).
Abstract: This work reports on implementing Mg implanted Edge Termination (ET), a simple but very useful technique to increase the breakdown voltage (BV) of the vertical $\beta $ -Ga2O3 Schottky barrier diode (SBD). With this ET, vertical $\beta $ -Ga2O3 SBD demonstrates a reverse blocking voltage of 1.55 kV and low specific on-resistance ( ${R} _{ \mathrm{\scriptscriptstyle ON},\textrm {sp}}$ ) of 5.1 $\text{m}\Omega \cdot \textrm {cm}^{\textrm {2}}$ at a lightly doped $\beta $ -Ga2O3 layer with epitaxial thickness of $10~\mu \text{m}$ , yielding a high power figure-of-merit (P-FOM) of 0.47 GW/cm2. Combined with high forward current on/off ratio of 108 ~ 109, Schottky barrier height of 1.01 eV, and ideality factor of 1.05, vertical $\beta $ -Ga2O3 Schottky Diode with implanted ET verifies its great potential for future power rectifiers.
TL;DR: In this article, the authors reported the synthesis of high quality MnPS3 crystals and their mechanical exfoliation onto pre-fabricated devices, and the use of atomic force microscopy and Raman spectroscopy yielded information on the number of layers.
Abstract: Layered metal thiophosphates with the general formula MPX3 (M is a group VI element and X is a chalcogen) have been emerging as a novel group of tunable bandgap semiconductors. Herein, we report the synthesis of high quality MnPS3 crystals, and their mechanical exfoliation onto pre-fabricated devices. The use of atomic force microscopy and Raman spectroscopy yielded information on the number of layers. MnPS3-based field effect transistors (FETs) comprising few-layer and bulk crystals with gold contacts show p-type conductivity with an on–off ratio of ∼103. Temperature dependent electrical transport measurements yield a Schottky barrier height value of 0.34 eV for few-layer devices. FETs based on multilayer and bulk MnPS3 show very similar transport characteristics. The transistor devices have also been shown to be good ultraviolet photodetectors with photoresponsivity of 288 A W−1 at a wavelength of 365 nm. Density functional theory calculations reveal the parameters that affect the viability of electron/hole doping in MnPS3 and help understand the p-type nature of the FET device.
04 Sep 2019
TL;DR: In this paper, a light and mechanical energy co-harvesting generator based on a dynamic metal/perovskite Schottky junction was demonstrated, and the output current was enhanced by 3-fold compared with the dynamic junction in the dark condition.
Abstract: Summary Although perovskite has been widely explored in optoelectronic devices, it has been rarely explored as a Schottky junction. Here, we demonstrate a light- and mechanical-energy co-harvesting generator based on a dynamic metal/perovskite Schottky junction. In dark conditions, by moving Al over perovskite film (conductivity: 70.0 S/cm), output voltage and current density of −0.70 V and −41.1 A/m2, respectively, are achieved. As defects eliminate the photo-generated carriers in the static metal/perovskite junction under light illumination, the photoresponse is negligible. Strikingly, the output current of dynamic metal/perovskite junction under light illumination is enhanced by 3-fold compared with the dynamic junction in the dark condition. This nonlinear photo-enhanced effect is proposed as a result of strong interaction between the photo-generated and bound back carriers in the dynamic Schottky junction as well as the high light-absorption coefficient of perovskite. A flexible Al/perovskite generator has been demonstrated as a wearable energy-harvesting device.
26 Feb 2019
TL;DR: Results show that the USS-derived ZnO/rGO samples exhibit high NO2-sensing property at low operating temperatures because of their high specific surface area and porous structures when compared with the ZnNO/ rGO sample obtained by the traditional precipitation method.
Abstract: This paper develops a novel ultrasonic spray-assisted solvothermal (USS) method to synthesize wrapped ZnO/reduced graphene oxide (rGO) nanocomposites with a Schottky junction for gas-sensing applic...
TL;DR: In this paper, the van der Waals (vdW) force is dominated by the interlayer interlayer spacing of 3.413 and binding energy per C atom of approximately 50 µmV.
TL;DR: In this article, a low-power ZnO active-layered thin-film (60 nm) Schottky diode-one memristor device was fabricated and the material makeup of the device was confirmed via energy dispersive X-ray spectroscopy.
Abstract: Resistive random access memories (RRAMs) are favorable contenders in the race towards future technologies. Moreover, the desirable properties of memristor-based RRAM devices make them very good competitors in this field. The sneak paths problem poses one of the main difficulties in the construction of crossbar memory devices. This problem can be effectively suppressed by applying the 1diode-1resistor (1D1R) design structure. The Schottky diode has many advantages compared to the PN junction diode. The low-power (∼1 µW) ZnO active-layered thin-film (60 nm thick) one Schottky diode-one memristor device fabricated in this study included a top Ag electrode and a bottom Al electrode. The material makeup of the device was confirmed via energy dispersive X-ray spectroscopy (EDAX). The memristive and Schottky diode characteristics of the Ag/ZnO/Al device were resolved by measuring the time-dependent voltage/current. The characteristic pinched hysteresis memristive loops were observed at the first quadrant of the current-voltage plane, whereas the diode curves were seen at the third quadrant. Using the current-voltage curves, the height of the Schottky barrier, ideality factor and threshold voltage of the Schottky diode were found to be 0.68 eV, 3.75 and 0.49 V, respectively. After physical implementation and characterization of the one diode-one memristor device, its anti-crosstalk characteristics were investigated. Taking into account the 10% read margin, the maximum crossbar size was found to be 87.