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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Electron sources based on diamond pin-diodes
摘要： Efficient electron sources are of ongoing interest in particular for space and terrestrial power telecommunications and radar applications. With conventional cathode technology based on thermionic- and field electron emission a novel approach for direct electron emission is realized through a diamond pin diode. Electrons injected into the conduction band of the intrinsic layer of the diode can be released into vacuum with a negative electron affinity surface of the i-layer. The diamond pin diodes were prepared on boron doped (p-type) substrates with (111) surface orientation. A high purity intrinsic and a phosphorus doped diamond layer (n-type, ~400nm thickness) were deposited in dedicated PECVD systems, respectively. An additional contact layer comprised of nanostructured carbon was grown in a dedicated PECVD. The layered device was processed by lithography utilizing an aluminum hard mask to etch mesa structures with diameters ranging from 50μm to 200μm. The final devices were treated in a pure hydrogen plasma to induce the negative electron affinity properties of the i-layer. After an annealing step in high vacuum individual pin diodes were biased in forward current and voltages up to 20V. The observation of light from the diode was attributed to the UV exciton state and indicated bipolar transport. At a diode current of about 80mA an electron emission current of 25μA was observed from a single 200μm diameter diode.
关键词： Diamond,solid state electronics,doping,phosphorus,electron emission,plasma-enhanced chemical vapor deposition,nanostructured carbon,pin diode,single crystal
更新于2025-09-23 15:21:21
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Catalytic growth of large area monolayer molybdenum disulfide film by chemical vapor deposition
摘要： Large area monolayer molybdenum disulfide (MoS2) film grown on silica/silicon substrate was synthesized using a catalyst perylene-3, 4, 9, 10-tetracarboxylic acid tetrapotassium salt (PTAS) by the method of chemical vapor deposition. The properties of the monolayer MoS2 film were characterized using a number of techniques. The optical microscope images show the film is uniform and continuous on a large scale. The 0.7 nm film thickness measured by atomic force microscope, as well as the difference of 20 cm-1 between the two characteristic Raman peaks, all prove that the film is single layer. The strong photoluminescence spectrum and image as well as the x-ray diffraction indicate that the monolayer MoS2 film has a good quality. The MoS2 film synthesized under the same conditions without PTAS was also characterized as a comparison. The results show that the MoS2 film tends to thicker without using PTAS, suggesting that PTAS can not only promote the formation of the MoS2 seeding, but also induce horizontal growth of the MoS2 film on the substrate.
关键词： Molybdenum disulfide,Chemical vapor deposition,Monolayer
更新于2025-09-23 15:21:21
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Fabrication of Two-Dimensional Arrays of Fluorescent Centers in Single-Crystalline Diamond Using Particle Beam Writing
摘要： Micrometer-scale patterning was performed using the particle beam writing technique with a focused heavy-ion microbeam, allowing the creation of a unique two-dimensional distribution of fluorescent centers in single-crystalline diamond. The focused nitrogen microbeam was scanned over the target of single-crystalline diamond prepared by chemical vapor deposition to create nitrogen-vacancy (NV) centers at defined positions. Imaging using a custom-built confocal fluorescence microscopy system revealed that the desired NV distribution was generated in the target crystal with a spatial resolution similar to the beam resolution. A two-dimensional matrix barcode test pattern was successfully generated in a diamond substrate to demonstrate the encryption of information inside a solid-state target.
关键词： diamond,particle beam writing,two-dimensional,chemical vapor deposition,nitrogen vacancy centers,confocal fluorescence microscopy
更新于2025-09-23 15:21:21
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Tenfold increase in the photostability of an azobenzene guest in vapor-deposited glass mixtures
摘要： Improvements to the photostability of organic glasses for use in electronic applications have generally relied on the modification of the chemical structure. We show here that the photostability of a guest molecule can also be significantly improved—without chemical modification—by using physical vapor deposition to pack molecules more densely. Photoisomerization of the substituted azobenzene, 4,4'-diphenyl azobenzene, was studied in a vapor-deposited glass matrix of celecoxib. We directly measure photoisomerization of trans- to cis-states via Ultraviolet-visible (UV-Vis) spectroscopy and show that the rate of photoisomerization depends upon the substrate temperature used during co-deposition of the glass. Photostability correlates reasonably with the density of the glass, where the optimum glass is about tenfold more photostable than the liquid-cooled glass. Molecular simulations, which mimic photoisomerization, also demonstrate that photoreaction of a guest molecule can be suppressed in vapor-deposited glasses. From the simulations, we estimate that the region that is disrupted by a single photoisomerization event encompasses approximately 5 molecules.
关键词： photostability,organic glasses,azobenzene,photoisomerization,physical vapor deposition,molecular simulations,UV-Vis spectroscopy
更新于2025-09-23 15:21:21
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Insights into the Role of Plasma in Atmospheric Pressure Chemical Vapor Deposition of Titanium Dioxide Thin Films
摘要： In this work, the effect of plasma on the chemistry and morphology of coatings deposited by Atmospheric Pressure Plasma Enhanced Chemical Vapor Deposition (AP-PECVD) is investigated. To do so, plasma deposited amorphous titanium dioxide (TiO2) thin films are compared to thin films deposited using Atmospheric Pressure Chemical Vapor Deposition (AP-CVD) not involving the use of plasma. We focus here on the effect and the interest of plasma in the AP-PECVD process over AP-CVD for low substrate temperature deposition. The advantages of AP-PECVD over AP-CVD are often suggested in many articles however no direct evidence of the role of the plasma for TiO2 deposition at atmospheric pressure was reported. Hence, herein, the deposition via both methods is directly compared by depositing coatings with and without plasma using the same CVD reactor. Through the control of the plasma parameters, we are able to form low carbon coatings at low temperature with a deposition rate twice faster than AP-CVD, clearly showing the interest of plasma. Plasma enhanced methods are promising for the deposition of coatings at industrial scale over large surface and at high rate.
关键词： AP-PECVD,TiO2 thin films,Atmospheric Pressure Chemical Vapor Deposition,Atmospheric Pressure Plasma Enhanced Chemical Vapor Deposition,plasma,AP-CVD,low substrate temperature deposition
更新于2025-09-23 15:21:01
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Revealing the Role of Gold in the Growth of Two-dimensional Molybdenum Disulfide by Surface Alloy Formation
摘要： Formation of Mo-Au surface alloy during Au-assisted chemical vapor deposition (CVD) of MoS2 was confirmed by a series of control experiments. We adapted a metalorganic chemical vapor deposition (MOCVD) system to conduct two-dimensional MoS2 growth in a controlled environment. Sequential injection of Mo and S precursors, which does not yield any MoS2 on a SiO2/Si, grows atomically thin MoS2 on Au, indicating formation of an alloy phase. Transmission electron microscopy of a cross-section of the specimen confirmed the confinement of the alloy phase near the surface only. These results show that the reaction intermediate is the surface alloy and that the role of Au in the Au-assisted CVD is formation of an atomically thin reservoir of Mo near the surface. This mechanism is clearly distinguished from that of MOCVD, which does not involve formation of any alloy phases.
关键词： Molybdenum Disulfide,Surface Alloy,Two-dimensional Material,Chemical vapor deposition,Metalorganic Chemical Vapor Deposition
更新于2025-09-23 15:21:01
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Applications of atomic layer deposition and chemical vapor deposition for perovskite solar cells
摘要： Metal halide perovskite solar cells (PSCs) have rapidly evolved over the past decade to become a photovoltaic technology on the cusp of commercialization. In the process, numerous fabrication strategies have been explored with the goal of simultaneously optimizing for device efficiency, stability, and scalability. Chemical vapor deposition (CVD) and atomic layer deposition (ALD) have proven to be effective tools for the fabrication of various components of PSCs. This review article examines the application of CVD and ALD for the deposition and modification of charge transport layers, passivation layers, absorber materials, encapsulants, and electrodes. It outlines the use of these vapor deposition techniques in state-of-the-art, multi-junction solar cell devices, and also contains a discussion of the stability of metal halide perovskite materials under CVD and ALD conditions based on in-situ characterization reported in literature. This article concludes with insights into future CVD and ALD research directions that could be undertaken to further aid the deployment of PSCs in emerging solar photovoltaic markets.
关键词： absorber materials,passivation layers,encapsulants,atomic layer deposition,charge transport layers,chemical vapor deposition,perovskite solar cells,electrodes
更新于2025-09-23 15:21:01
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Ultra-long high quality catalyst-free WO<sub>3</sub> nanowires for fabricating high-performance visible photodetectors
摘要： This work presents a study on the controlled growth of WO3 nanowires via chemical vapor deposition without catalyst, and their potential applications in visible photodetectors. The influence of growth conditions on the morphology of WO3 nanowires is studied in order to understand the growth mechanism of WO3 nanowires, and ultra-long (60 μm, the longest one ever reported) WO3 nanowires with a spindle shape are achieved by optimizing the growth conditions. The photoconductor detectors based on WO3 single nanowires present excellent device performance with a responsivity as high as 19 A/W at a bias of 0.1 V, a detectivity as high as 1.06 × 1011 Jones, and a response (rising and decay) time as short as 8 ms under the illumination of a 404 nm laser. These results indicate the great potential of WO3 nanowires for applications in fabricating high performance visible photodetectors.
关键词： visible light,high performance,photodetectors,chemical vapor deposition,WO3 nanowires
更新于2025-09-23 15:21:01
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High-performance and Flexible CsPbBr3UV-vis Photodetectors Fabricated via Chemical Vapor Deposition
摘要： Inorganic perovskite cesium lead halide (CsPbBr3) has attracted considerable attention because of its particularly excellent optoelectronics properties and high stability in humidity environments. Here, highly crystalline CsPbBr3 films with different morphologies and grain sizes were prepared via a one-step low pressure chemical vapor deposition (CVD). The structure-activity relationship between film microstructure and photodetectors (PDs) performance are investigated. The CsPbBr3 PD prepared at ~190 ℃ possess an excellent response in the UV-Vis region and exhibits a fast response time of 0.7 ms/1.0 ms. Under 405 nm laser irradiation, the PD has a high responsivity, detectivity, external quantum efficiency, and switch ratio of 3.49 A/W, 1.50×1013 Jones, 1075.4%, and 3.29×105, respectively. More importantly, the PD maintains 93% of original photocurrent when exposed to air for 28 days, which demonstrates excellent stability. At the same time, the CsPbBr3 films prepared via CVD are not dependent on the substrate, and the PDs exhibit similar performance on glass, SiO2/Si and polyimide (PI) substrates. The photocurrent of the flexible PD is maintained at 86% of the initial device performance parameters after 1000 bending cycles. These results indicate that the CsPbBr3 perovskite films prepared via CVD have great potential for application in high-performance, stable and flexible PDs.
关键词： photodetector,chemical vapor deposition,stability,CsPbBr3,flexible
更新于2025-09-23 15:21:01
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Low temperature platinum chemical vapor deposition on functionalized self-assembled monolayers
摘要： The reaction pathways of Pt CVD using (COD)PtMe2 – xClx (x = 0, 1, 2) have been investigated on functionalized self-assembled monolayers (SAMs) as models for organic substrates. Residual gas analysis for (COD)PtMe2 and (COD)PtMeCl is consistent with the loss of methyl radicals as the initial step in deposition, while for (COD)PtCl2, the first step is the loss of a chlorine radical. It is further shown using x-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry that the deposition process leads to chemical damage of the SAM layer and little Pt deposition. Using this understanding, it is demonstrated that the Pt CVD rate can be controlled using a radical trap. In the presence of 1,4-cyclohexadiene, a well-known alkyl radical trap, Pt deposition was increased by 5× to 10×, creating a room-temperature effective Pt CVD process.
关键词： time-of-flight secondary ion mass spectrometry,x-ray photoelectron spectroscopy,Pt CVD,chemical vapor deposition,self-assembled monolayers,radical trap
更新于2025-09-23 15:21:01