- 标题
- 摘要
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- 实验方案
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Tuning Contact Resistance in Top-Contact <i>p</i> -Type and <i>n</i> -Type Organic Field Effect Transistors by Self-Generated Interlayers
摘要： Contact resistance significantly limits the performance of organic field-effect transistors (OFETs). Positioning interlayers at the metal/organic interface can tune the effective work-function and reduce contact resistance. Myriad techniques offer interlayer processing onto the metal pads in bottom-contact OFETs. However, most methods are not suitable for deposition on organic films and incompatible with top-contact OFET architectures. Here, a simple and versatile methodology is demonstrated for interlayer processing in both p- and n-type devices that is also suitable for top-contact OFETs. In this approach, judiciously selected interlayer molecules are co-deposited as additives in the semiconducting polymer active layer. During top contact deposition, the additive molecules migrate from within the bulk film to the organic/metal interface due to additive-metal interactions. Migration continues until a thin continuous interlayer is completed. Formation of the interlayer is confirmed by X-ray photoelectron spectroscopy (XPS) and cross-section scanning transmission electron microscopy (STEM), and its effect on contact resistance by device measurements and transfer line method (TLM) analysis. It is shown that self-generated interlayers that reduce contact resistance in p-type devices, increase that of n-type devices, and vice versa, confirming the role of additives as interlayer materials that modulate the effective work-function of the organic/metal interface.
关键词： organic electronics,TLM,self-generated interlayers,organic field-effect transistors
更新于2025-09-23 15:22:29
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Long-Range Activationless Photostimulated Charge Transport in Symmetric Molecular Junctions
摘要： Molecular electronic junctions consisting of nitroazobenzene oligomers covalently bonded to a conducting carbon surface using an established 'all-carbon' device design were illuminated with UV?vis light through a partially transparent top electrode. Monitoring junction conductance with a DC bias imposed permitted observation of photocurrents while varying the incident wavelength, intensity, molecular layer thickness, and temperature. The photocurrent spectrum tracked the in situ absorption spectrum of nitroazobenzene, increased linearly with light intensity, and depended exponentially on applied bias. The electronic characteristics of the photocurrent differed dramatically from those of the same device in the dark, with orders of magnitude higher conductance and very weak attenuation with molecular layer thickness (β = 0.14 nm?1 for thickness above 5 nm). The temperature dependence of the photocurrent was opposite that of the dark current, with a 35% decrease in conductance between 80 and 450 K, while the dark current increased by a factor of 4.5 over the same range. The photocurrent was similar to the dark current for thin molecular layers but greatly exceeded the dark current for low bias and thick molecular layers. We conclude that the light and dark mechanisms are additive, with photoexcited carriers transported without thermal activation for a thickness range of 5?10 nm. The inverse temperature dependence is likely due to scattering or recombination events, both of which increase with temperature and in turn decrease the photocurrent. Photostimulated resonant transport potentially widens the breadth of conceivable molecular electronic devices and may have immediate value for wavelength-specific photodetection.
关键词： charge transport,optoelectronics,photocurrent,molecular electronics,molecular orbital energy,tunneling barrier,HOMO?LUMO gap,photoinduced transport
更新于2025-09-23 15:22:29
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The CMS Beam Halo Monitor electronics
摘要： The CMS Beam Halo Monitor has been successfully installed in the CMS cavern in LHC Long Shutdown 1 for measuring the machine induced background for LHC Run II. The system is based on 40 detector units composed of synthetic quartz Cherenkov radiators coupled to fast photomultiplier tubes (PMTs). The readout electronics chain uses many components developed for the Phase 1 upgrade to the CMS Hadronic Calorimeter electronics, with dedicated firmware and readout adapted to the beam monitoring requirements. The PMT signal is digitized by a charge integrating ASIC (QIE10), providing both the signal rise time, with few nanosecond resolution, and the charge integrated over one bunch crossing. The backend electronics uses microTCA technology and receives data via a high-speed 5 Gbps asynchronous link. It records histograms with sub-bunch crossing timing resolution and is read out via IPbus using the newly designed CMS data acquisition for non-event based data. The data is processed in real time and published to CMS and the LHC, providing online feedback on the beam quality. A dedicated calibration monitoring system has been designed to generate short triggered pulses of light to monitor the efficiency of the system. The electronics has been in operation since the first LHC beams of Run II and has served as the first demonstration of the new QIE10, Microsemi Igloo2 FPGA and high-speed 5 Gbps link with LHC data.
关键词： Cherenkov and transition radiation,Front-end electronics for detector readout,Beam-line instrumentation (beam position and profile monitors; beam-intensity monitors; bunch length monitors)
更新于2025-09-23 15:22:29
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GaN Integration Technology, an Ideal Candidate for High-Temperature Applications: A Review
摘要： In many leading industrial applications such as aerospace, military, automotive, and deep-well drilling, extreme temperature environment is the fundamental hindrance to the use of microelectronic devices. Developing an advanced technology with robust electrical and material properties dedicated for high-temperature environments represents a significant progress allowing to control and monitor the harsh environment regions. It may avoid using cooling structures while improving the reliability of the whole electronic systems. As a wide bandgap semiconductor, gallium nitride is considered as an ideal candidate for such environments, as well as in high-power and high-frequency applications. We review in this paper the main reasons that offer superiority to GaN devices over better-known technologies such as silicon (Si), silicon-on-insulator, gallium arsenide (GaAs), silicon germanium (SiGe), and silicon carbide (SiC). The theory of operation and main challenges at high temperature are discussed, notably those related to materials and contacts. In addition, the main limitations of GaN, including the technological (thermal and chemical) and intrinsic (current collapse and device self-heating) features are provided. In addition, the GaN devices recently developed for high-temperature applications are examined.
关键词： wide-bandgap semiconductors,high-temperature electronics,Extreme temperature applications,gallium-nitride technology
更新于2025-09-23 15:22:29
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[IEEE 2017 14th IEEE India Council International Conference (INDICON) - Roorkee (2017.12.15-2017.12.17)] 2017 14th IEEE India Council International Conference (INDICON) - Paper Based Flexible Carbon-FET Devices by Embedding Si Nanoparticles in Graphite Channel
摘要： A paper based carbon-FET (C-FET) was developed with graphite as channel. The performance of the fabricated C-FET was enhanced by embedding Si nanoparticles (SiNP) with the graphite. Initially, graphite was brush coated on paper substrate by mechanically rubbing a graphite source to fabricate the channel. However, to embed SiNP, the graphite was brush coated in presence of SiNPs, which formed graphite-SiNP composite and improved the performance of the device. It was observed that due to the presence of SiNP, the effect of gate voltage was improved approximately by a factor of four. The device was operated in back gate configuration with the paper as the dielectric material. Effect of loading of SiNP was also checked and it was found that the performance of the device improved with increase in SiNP loading. Thus, a carbon-FET was demonstrated with flexible substrate, which can be useful for different sensing and flexible electronic applications. Further, it was also observed that the performance of the C-FET was improved by adding semiconducting SiNPs. This approach of fabricating flexible paper based C-FETs are expected to be applied in the development of economical, replaceable, environment friendly, and disposable biomedical or point-of-care (POC) instruments, sensors, wearable and flexible electronic devices which will be affordable for a larger section of society.
关键词： Flexible electronics,Graphite,Nanoparticles,FET
更新于2025-09-23 15:22:29
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Strain-Engineered Ultrahigh Mobility in Phosphorene for Terahertz Transistors
摘要： Carrier mobility is a key parameter for the operation of electronic devices as it determines the ON state current and switching speed/frequency response of transistors. 2D phosphorene is considered as a potential candidate for field-effect transistors due to its high mobility. Here it is proposed to further enhance the carrier mobility of phosphorene and device performance via strain engineering. A systematic ab initio investigation on the anisotropic electronic structure of few-layer phosphorene reveals that the monolayer under 7.5–10% strain along zigzag direction shows an exceptional carrier mobility of ≈106 cm2 V?1 s?1, which is 10 times higher than the strain-free case. The simulated device performance shows that strain-engineered phosphorene–based field-effect transistors demonstrate a cut-off frequency of ≈1.14 THz with a gate length of 1.0 micron and 112 THz with a sub-10 nm gate length.
关键词： carrier mobility,density functional theory,phosphorene,transistors,strain-engineered electronics
更新于2025-09-23 15:22:29
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Direct-printed nanoscale metal-oxide-wire electronics
摘要： One-dimensional metal oxide (MO) micro-wires and nano-wires (MOWs) can be excellent functional units for integrated and transparent electronics. However, MOWs produced using conventional synthesis methods are short, uncontrollable, and randomly-distributed, so they cannot be easily used to fabricate high-density transistor arrays with precisely-controlled MOW-channels. Here, we describe a large-scale direct-printed universal nanoscale MOW electronics which includes highly-aligned, digitally-controlled and arbitrarily-long MOW arrays and various nanoscale applications of MOW field-effect transistors (FETs), neuromorphic synaptic transistors, and gas sensors. Broad classes of pristine, doped and alloyed MOWs are fabricated, so we demonstrated all-MOWFETs composed of conducting indium oxide (In2O3) wires and semiconducting indium zinc oxide (IZO) wires; the devices show a high carrier mobility μ ~17.67 cm2 V-1 s-1, comparable to μ of MO thin-film FETs. MOW synaptic transistors show presynaptic signals dependent postsynaptic behaviors similar to biological synaptic responses; which can be promising nano-electronic units of high-density neuromorphic devices. We also demonstrated MOW gas sensors which show high response to NO2 gas. Our direct-printed, large-scale, and individually-controlled MOW electronics would be a promising approach in development of industrially-viable MOW electronics and open new horizons for precisely-controlled inorganic MOW electronics and nanoscale printed electronics.
关键词： synaptic transistors,metal oxide nanowires,metal oxide gas sensors,nanowire printing,metal oxide transistors,nanowire electronics
更新于2025-09-23 15:22:29
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Bay-Linked Perylenediimides are Two Molecules in One: Insights from Ultrafast Spectroscopy, Temperature Dependence, and Time-Dependent Density Functional Theory Calculations
摘要： Bay-linked di-perylenediimide (di-PDI) molecules are finding increasing use in organic electronics due to their steric hindrance that 'twists' the two monomer units relative to one another, decreasing molecular aggregation. In this paper we explore the electronic spectroscopy and ultrafast dynamics of the singly-linked β-β-S-di-PDI (2,9'-di(undecan-5-yl)-2',9-di(undecan-6-yl)-[5,5'-bianthra[2,1,9-def:6,5,10-d'e'f']diisoquinolin]-1,1',3,3',8,8',10,10'(2H,2'H,9H,9'H)-octaone). Excitation-emission spectroscopy reveals two distinct emitting species, which are further characterized by time-dependent density functional theory (TD-DFT), demonstrating that the bay-linked PDI dimers exist in two geometrical conformations. These conformations are an 'open' geometry, where the two monomer sub-units are oriented nearly at right angles, giving them more J-like coupling, and a 'closed' geometry, in which the two monomer sub-units are nearly π-stacked, resulting in more H-like coupling. Given the extent of through-space and through-bond coupling, however, neither di-PDI conformer can be well-described simply in terms of independently-coupled monomers; instead, a full quantum chemistry description is required to understand the electronic structure of this molecule. Temperature-dependent experiments and the TD-DFT calculations indicate that the 'closed' conformer is ～70 meV more stable than the 'open' conformer, so that both conformers are important to the behavior of the molecule at room temperature and above. We use a combination of steady-state and femtosecond transient absorption and emission spectroscopies to globally fit the multiple electronic transitions underlying the spectra of both the 'closed' and 'open' conformers, which agree well with the TD-DFT calculations. The fact that di-PDI molecules are molecular species that adopt two distinct quasi-independent chemical identities has important ramifications for charge trapping and mobility in the organic electronic devices employing these materials.
关键词： TD-DFT calculations,ultrafast spectroscopy,conformational isomers,organic electronics,Bay-linked perylenediimides
更新于2025-09-23 15:22:29
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A review of the most recent progresses of state-of-art gallium oxide power devices
摘要： Until very recently, gallium oxide (Ga2O3) has aroused more and more interests in the area of power electronics due to its ultra-wide bandgap of 4.5–4.8 eV, estimated critical field of 8 MV/cm and decent intrinsic electron mobility limit of 250 cm2/(V·s), yielding a high Baliga’s figures-of-merit (FOM) of more than 3000, which is several times higher than GaN and SiC. In addition to its excellent material properties, potential low-cost and large size substrate through melt-grown methodology also endows β-Ga2O3 more potential for future low-cost power devices. This article focuses on reviewing the most recent advances of β-Ga2O3 based power devices. It will be starting with a brief introduction to the material properties of β-Ga2O3 and then the growth techniques of its native substrate, followed by the thin film epitaxial growth. The performance of state-of-art β-Ga2O3 devices, including diodes and FETs are fully discussed and compared. Finally, potential solutions to the challenges of β-Ga2O3 are also discussed and explored.
关键词： power electronics,power devices,gallium oxide
更新于2025-09-23 15:22:29
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A roadmap for electronic grade 2D materials
摘要： Since their modern debut in 2004, 2-dimensional (2D) materials continue to exhibit scientific and industrial promise, providing a broad materials platform for scientific investigation, and development of nano- and atomic-scale devices. A significant focus of the last decade’s research in this field has been 2D semiconductors, whose electronic properties can be tuned through manipulation of dimensionality, substrate engineering, strain, and doping (Mak et al 2010 Phys. Rev. Lett. 105 136805; Zhang et al 2017 Sci. Rep. 7 16938; Conley et al 2013 Nano Lett. 13 3626–30; Li et al 2016 Adv. Mater. 28 8240–7; Rhodes et al 2017 Nano Lett. 17 1616–22; Gong et al 2014 Nano Lett. 14 442–9; Suh et al 2014 Nano Lett. 14 6976–82; Yoshida et al 2015 Sci. Rep. 5 14808). Molybdenum disulfide (MoS2) and tungsten diselenide (WSe2) have dominated recent interest for potential integration in electronic technologies, due to their intrinsic and tunable properties, atomic-scale thicknesses, and relative ease of stacking to create new and custom structures. However, to go ‘beyond the bench’, advances in large-scale, 2D layer synthesis and engineering must lead to ‘exfoliation-quality’ 2D layers at the wafer scale. This roadmap aims to address this grand challenge by identifying key technology drivers where 2D layers can have an impact, and to discuss synthesis and layer engineering for the realization of electronic-grade, 2D materials. We focus on three fundamental areas of research that must be heavily pursued in both experiment and computation to achieve high-quality materials for electronic and optoelectronic applications.
关键词： transition metal dichalcogenides,2D materials,grand challenges,technology drivers,2D electronics,synthesis,roadmap
更新于2025-09-23 15:22:29