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Enhanced electron field emission from nanocrystalline orthorhombic boron nitride films
摘要： Nanocrystalline orthorhombic boron nitride (oBN) thin films with an island-in-honeycomb morphology were prepared on graphite substrate by radio frequency (r.f.) magnetron sputtering. The Field emission (FE) measurement results indicated that the FE properties are significantly enhanced in oBN films compared to high quality cBN films, the turn-on electric field of oBN films is decreased from 17.0 V/μm to 6 V/μm, and the highest emission current density is increased from 2.8 × 10?? to 3 × 10?? A/cm2. The enhanced FE properties of the oBN films can be attributed to significant reduction in effective potential barrier caused by both protruded island-in-honeycomb morphology and honeycomb-like interconnected internal structure.
关键词： Semiconductors,Thin films,Electron field emission,Boron nitride,Physical vapour deposition
更新于2025-09-23 15:22:29
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Recent progress on jet printing of oxide-based thin film transistors
摘要： Among the printing technologies for printed electronics, jet printing-based methods provide promising solutions to the fabrication of oxide-based thin film transistors (TFTs) for flexible and non-flexible electronics. Their direct patterning capability, non-vacuum and solution-based material formation process have attracted a significant amount of interests from both the academic and industry sectors. This topical review summarizes recent progress on the development of jet printed metal oxide TFTs with special attention given to the surface related effects, ink preparation and post-printing treatments, which are the critical aspects of obtaining high performance printed TFTs. Firstly, a brief introduction is made on the state of art jet printing technologies: the piezoelectric/thermal inkjet printing, the newly emerged electro-hydrodynamic jet printing and aerosol jet printing. Then, surface related issues of wettability and coffee-ring effect are discussed. At last, jet printing of oxide-based TFTs is reviewed according to the classification of printed material types: metal oxide semiconductors, gate dielectrics and conductive electrodes. The extensive review of low temperature annealing methods made this work particular interesting to the printing of oxide-based TFTs on flexible substrates.
关键词： gate dielectric,jet printing,oxide-based semiconductors,thin film transistors,electrode
更新于2025-09-23 15:22:29
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A comparison of the morphological and electrical properties of sol-gel dip coating and atomic layer deposition of ZnO on 3D nanospring mats
摘要： We report on the morphological and electrical properties, with (light) and without (dark) UV illumination, of conformal coatings of ZnO on silica nanosprings deposited by sol-gel and atomic layer deposition (ALD) for the first time. Field Emission Scanning Electron Microscopy (FESEM) imaging showed that both methods produce conformal coatings of ZnO on the nanosprings. The surface of the sol-gel coatings exhibited cracks at higher numbers of dipping/sintering cycles, while the morphology of ALD ZnO films were always smooth and devoid of cracks. The effective photoconductivity of the sol-gel ZnO coated nanospring mats increased nonlinearly with increasing coating thickness. The corresponding dark effective conductivity of the sol-gel ZnO coated nanospring mats also increased within the same thickness range. Alternatively, the effective photoconductivity of the ALD ZnO coated nanospring mats increased linearly with increasing coating thickness. The corresponding dark effective conductivity also increased within the same thickness range. The superior effective conductivity and photoconductivity of the ALD ZnO coated nanospring mats is attributed to the uniformity of the coating and the absence of cracks, which are observed for the thicker sol-gel ZnO coatings.
关键词： atomic layer deposition (ALD),semiconductors,sol-gel,nanosprings,field emission scanning electron microscopy,conductivity,ZnO
更新于2025-09-23 15:22:29
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Preparation of a Photoactive 3D Polymer Pillared with Metalloporphyrin
摘要： Among the very few efforts for the preparation of stable pillared graphene nanostructures, there is no report of tin porphyrin intercalated between TiO2-graphene (TG) nanosheets. In this study, a nanostructure material of pillared graphene made of tin porphyrin functionalized graphene-TiO2 composite (TG) was successfully synthesized. The prepared compound showed high activity in the photodegradation reaction under irradiation of visible light. Photocatalytic results showed that the composite of graphene-TiO2 containing 3% graphene had the highest photoactivity. The photoactivity of TG (3%) was about 1.5 times higher than that of the pure TiO2. Besides, tin porphyrin-pillared TG composite (TGSP) material exhibited an excellent visible light photocatalytic performance in degradation of methyl orange dye. This compound could destruct 100% of methyl orange dye in 180 min. Such pillared carbon nanostructure exhibited unique photoactivity due to the synergistic effect between the graphene sheets and the SnTCPP pillars. It is found that the highly efficient light-harvesting structure of the SnTCPP pillared TG composite can be attributed to densely embedded porphyrin chromophores with high visible absorptivity within the framework. The investigation of photocatalytic mechanism determined that hydroxyl radical is a main species in photodegradation process of methyl orange over TGSP compound.
关键词： Semiconductors,Nanostructure,Material,Photocatalytic
更新于2025-09-23 15:22:29
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Recent Advancement of Semiconductor Materials and Devices
摘要： 本論文では, 主に GaAs および GaAs 系混晶半導体の MBE 成長とそのデバイス応用について取り上げたが, その他にも窒化物半導体, 酸化物半導体, II-VI 族半導体といった多くの半導体の成長や, 量子細線, 量子ドットのような量子井戸以上に複雑な構造の製作にも MBE 法は活用されている. 基礎研究から実用化まで, 半導体デバイスの開発において MBE 法が成し遂げてきた功績は極めて大きい. 今後も素子構造の製作, 新規半導体材料の成長, 結晶欠陥の制御など様々な要求のある結晶成長時に MBE 法は活用され続けるであろう.
关键词： Compound semiconductors,Optical and electronic devices,Molecular beam epitaxy
更新于2025-09-23 15:22:29
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Half-metallic ferromagnetic behavior in (Ga, Cr)N and (Ga, Cr, V)N compounds for spintronic technologies: Ab-initio and Monte Carlo methods
摘要： In this article, we investigate the magnetic- and electronic-proprieties of GaN doped with simple- and double-impurities utilizing Ab-initio and Monte Carlo studies. We have predicted that (Ga, Cr)N and (Ga, Cr, V)N compounds exhibit ferromagnetic- and halfmetallic-behavior with 100% spin-polarization at the Fermi-level. Moreover, we have found that Ga1-xCrxN and Ga1-2xCrxVxN (x = 0.04, 0.05 and 0.06) show a 2nd order ferromagnetic transition and that their Tc is above room temperature. These predictions make (Ga, Cr)N and (Ga, Cr, V)N compounds strong-candidates for spintronic-technologies.
关键词： Ab-initio calculations,Monte Carlo method,Diluted magnetic semiconductors,Spintronic,Gallium Nitride
更新于2025-09-23 15:22:29
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Effect of the length of a symmetric branched side chain on charge transport in thienoisoindigo-based polymer field-effect transistors
摘要： Compounds consisting of the electron-accepting thienoisoindigo (TIIG) moiety with branched alkyl side chains of various lengths were each copolymerized with thiophenylene vinylene thiophene (TVT) and selenophenylene vinylene selenophene (SVS) donor moieties, to investigate how the length of the side chain between the branch point and backbone affects the microstructure and charge transport of thin films made of these TIIGTVT and TIIGSVS copolymers. All of the organic field-effect devices based on these copolymers exhibited p-type behaviors, and these devices displayed hole mobility values as high as 1.15 cm2/V/s. Interestingly, the longer side chains in both series of TIIGTVT and TIIGSVS copolymers, the more improved was the molecular ordering of the thin films. But the relationship between charge mobility and side chain length differed for these two series of copolymers, a result attributed to differences between the microstructures of their films. The TIIGTVT series showed localized aggregation, with the greater length of the side chain between the branch point and backbone enhancing the charge transport by increasing the quantity and average size of the aggregates. In contrast, the TIIGSVS series showed long-range order, and aggregates that were too large and prevented charge transport.
关键词： side-chain engineering,thienoisoindigo,polymer field-effect transistor,Polymeric semiconductors
更新于2025-09-23 15:21:21
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Non-radiative processes in metal halide perovskite semiconductors probed by photoluminescence microscopy
摘要： Organo metal halide perovskites are solution processed semiconductors that recently attracted a great attention. They possess a rather “soft” and (photo) chemically active solid structure allowing for ion migration and other mass diffusion processes. This is a likely reason why non-radiative recombination centres in these materials are activated and de-activated on relatively slow time-scales. This dynamics reveals as photoluminescence (PL) fluctuations (blinking) of individual microcrystals and local areas of films and allows for application of a broad range of single molecule spectroscopy methods including optical super-resolution. Studying PL blinking resolves properties of individual non-radiative centres and helps to unravel their chemical nature.
关键词： perovskite,metal halide,Non-radiative processes,semiconductors,photoluminescence microscopy
更新于2025-09-23 15:21:21
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Selective Transfer of Rotationally Commensurate MoS <sub/>2</sub> from an Epitaxially Grown van der Waals Heterostructure
摘要： Large-scale synthesis of high quality two-dimensional (2D) semiconductors are critical for their incorporation in emerging electronic and optoelectronic technologies. In particular, chemical vapor deposition (CVD) of transition metal dichalcogenides (TMDs) via van der Waals epitaxy on epitaxial graphene (EG) leads to rotationally commensurate TMDs in contrast to randomly aligned TMDs grown on amorphous oxide substrates. However, the interlayer coupling between TMDs and EG hinders the investigation and utilization of the intrinsic electronic properties of the resulting TMDs, thus requiring their isolation from the EG growth substrate. To address this issue, we report here a technique for selectively transferring monolayer molybdenum disulfide (MoS2) from CVD-grown MoS2-EG van der Waals heterojunctions using copper (Cu) adhesion layers. The choice of Cu as the adhesion layer is motivated by density functional theory calculations that predict the preferential binding of monolayer MoS2 to Cu in contrast to graphene. Atomic force microscopy and optical spectroscopy confirm the large-scale transfer of rotationally commensurate MoS2 onto SiO2/Si substrates without cracks, wrinkles, or residues. Furthermore, the transferred MoS2 shows high performance in field-effect transistors with mobilities up to 30 cm2/Vs and on/off ratios up to 106 at room temperature. This transfer technique can likely be generalized to other TMDs and related 2D materials grown on EG, thus offering a broad range of benefits in nanoelectronic, optoelectronic, and photonic applications.
关键词： molybdenum disulfide,van der Waals epitaxy,two-dimensional semiconductors,field-effect transistors,copper adhesion layers,transition metal dichalcogenides,chemical vapor deposition
更新于2025-09-23 15:21:21
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Setup to Study the in Situ Evolution of Both Photoluminescence and Absorption during the Processing of Organic or Hybrid Semiconductors
摘要： In situ measurement techniques, applied during the solution processing of novel semiconductors such as organic semiconductors or hybrid perovskites, have become more and more important to understand their film formation. In that context, it is crucial to determine how the optical properties, namely photoluminescence (PL) and absorption, evolve during processing. However, until now PL and absorption have mostly been investigated independently, significantly reducing the potential insights into film formation dynamics. To tackle this issue we present the development of a detection system that allows simultaneous measurement of full absorption and PL spectra during solution processing of the investigated film. We also present a spin-coater system attachable to the detection system, where the temperature of the substrate on which the film is processed can be changed. We performed test measurements by spin coating the well-known conjugated polymer P3HT demonstrating the potential of this technique. By considering absorption and corresponding PL, we extract the PL quantum yield (PLQY) during processing, which decreases with substrate temperature. Furthermore, we identify a significant red shift of the PL just prior to the onset of the aggregation process, indicating the importance of chain planarization prior to solid film formation.
关键词： photoluminescence,in situ measurement,organic semiconductors,hybrid perovskites,spin-coating,film formation,absorption,P3HT
更新于2025-09-23 15:21:21