We propose an epitaxial punchthrough diode for bipolar resistance RAM (RRAM) selector application. Epitaxial Si:C process is used to deposit n + /p/n + layers which are fabricated into ...300-nm-diameter vertical punchthrough diodes. High on-current density of >; 1 MA/cm 2 and high on/off current ratio of >; 250 and >; 4700 (at opposite polarities) are observed. A switching speed of <; 10 ns is measured. On-voltage designability is demonstrated by tuning the p-region doping and length. The comparison of experimental IV with Sentaurus TCAD-simulated IV characteristics confirms the punchthrough mechanism. Comparison with other bipolar RRAM selector technologies highlights the overall advantages of punchthrough-based selector.
In situ Formula Omitted and Formula Omitted measurements were performed during the 120 MeV AuFormula Omitted ion irradiation on the Pt/AlFormula Omitted-Ga2O3, metal–oxide–semiconductor capacitors ...(MOSCAPs), to comprehend the swift heavy ion (SHI)-induced effects at the interface and in the device performance. At a maximum fluence of Formula Omitted ions/cm2, the Formula Omitted data showed a rise in the reverse leakage current by four orders of magnitude compared to the pristine device. The trap level (below the conduction band of Al2O3) from Poole–Frenkel emission exhibits a variation from Formula Omitted1.1 to 0.91 eV. The conduction band offset Formula Omitted of AlFormula Omitted-Ga2O3 changes from 1.48 to 1.25 eV as estimated under the Fowler–Nordheim tunneling mechanism. In situ Formula Omitted measurements show a significant shift in the flat band voltages and increased oxide in the border and interface due to charge trapping. The X-ray photoelectron spectroscopy (XPS) measurements of Al 2p and O 1s core levels revealed the pre-existing oxygen defects in Al2O3, which increase with fluence. The deconvoluted peaks of Al 2p at 74.6 eV designated to Al-sub oxide and the O 1s peak variation in the FWHM signifies the increase in the O defects. Cross-sectional transmission electron microscopy (XTEM) measurements on the irradiated device (at Formula Omitted ions/cmFormula Omitted revealed a modulated interface of AlFormula Omitted-Ga2O3 and the formation of an interlayer of Formula Omitted4 nm Al x GayOz. The scanning transmission electron microscope (STEM)-based high-angle annular dark-field imaging (HAADF) energy-dispersive X-ray spectroscopy (EDS) mapping revelation and the depth profiles of XPS data confirm the formation of an Al x GayOz interlayer.
Abstract
Modulation of photoluminescence of atomically thin transition metal dichalcogenide two-dimensional materials is critical for their integration in optoelectronic and photonic device ...applications. By coupling with different plasmonic array geometries, we have shown that the photoluminescence intensity can be enhanced and quenched in comparison with pristine monolayer MoS
2
. The enhanced exciton emission intensity can be further tuned by varying the angle of polarized incident excitation. Through controlled variation of the structural parameters of the plasmonic array in our experiment, we demonstrate modulation of the photoluminescence intensity from nearly fourfold quenching to approximately threefold enhancement. Our data indicates that the plasmonic resonance couples to optical fields at both, excitation and emission bands, and increases the spontaneous emission rate in a double spacing plasmonic array structure as compared with an equal spacing array structure. Furthermore our experimental results are supported by numerical as well as full electromagnetic wave simulations. This study can facilitate the incorporation of plasmon-enhanced transition metal dichalcogenide structures in photodetector, sensor and light emitter applications.
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•Shrinkage of the oil phase from O/W emulsions pushes the hydrophobic γ-Fe2O3 NPs in to the pores.•Porous silica only with straight pores can entrap nanoparticles by this facile ...process.•Developed magnetic assembly system exhibits superparamagnetic behavior.•γ-Fe2O3 NPs assembled in the pores generate strong local magnetic field resulting in higher r2 relaxivity.
The present work reports a novel strategy of assembling maghemite (γ-Fe2O3) nanoparticles (NPs) in mesoporous silica host for developing a highly efficient MRI contrast probe. Shrinkage of hydrophobic environment due to the continuous evaporation of chloroform from Chloroform-in-Water emulsions pushes the hydrophobic γ-Fe2O3 NPs towards the hydrophobic pores of silica spheres resulting in a water soluble dense assembly structure. Mesoporous silica only with straight pores is found to be suitable for this particular entrapment process, while with curved and twisted pores, NPs are found to be seated on the surface only. So-developed assembly system has retained the superparamagnetic behaviour of its comprising NPs and exhibited high colloidal stability and biocompatibility. A significant enhancement in MRI transverse relaxivity to 386.2 mM−1 s−1 from 191.8 mM−1 s−1 of isolated primary γ-Fe2O3 NPs, has been obtained due to the strong magnetic field generated by the large number of NPs packed in the porous channels and consequent faster relaxation process. The fabrication strategy can be extended for the development of designed secondary nanostructures with new magnetic effects and physical properties.
A microfocus X‐ray fluorescence spectroscopy beamline (BL‐16) at the Indian synchrotron radiation facility Indus‐2 has been constructed with an experimental emphasis on environmental, archaeological, ...biomedical and material science applications involving heavy metal speciation and their localization. The beamline offers a combination of different analytical probes, e.g. X‐ray fluorescence mapping, X‐ray microspectroscopy and total‐external‐reflection fluorescence characterization. The beamline is installed on a bending‐magnet source with a working X‐ray energy range of 4–20 keV, enabling it to excite K‐edges of all elements from S to Nb and L‐edges from Ag to U. The optics of the beamline comprises of a double‐crystal monochromator with Si(111) symmetric and asymmetric crystals and a pair of Kirkpatrick–Baez focusing mirrors. This paper describes the performance of the beamline and its capabilities with examples of measured results.
To determine whether chronic oxygen dependency at the time of discharge from the neonatal intensive care unit (NICU) in infants with bronchopulmonary dysplasia (BPD) predicts respiratory outcomes at ...3 years.
Preterm infants ⩽1250 g without BPD, BPD and BPD with chronic oxygen dependency were identified from the Southern Alberta Perinatal Follow-up clinic database (1995-2007). Respiratory outcomes at 4, 8, 18 and 36 months corrected age following NICU discharge were examined. Univariate analyses were done.
Out of 1563 infants admitted to the NICU, 1212 survived. Complete follow-up data at 36 months were available for 1030 (85%) children. Children with BPD with or without chronic oxygen dependency had significantly (P<0.001) lower birth weights and gestational ages, and greater post-natal steroid use, compared with those with no BPD. At 4, 8 and 18 months follow-up, the use of respiratory medications and supplemental oxygen were both significantly higher in the BPD infants with chronic oxygen dependency group compared with the no-BPD group and BPD group. At 36 months, children in the BPD with chronic oxygen dependency group were more likely to use respiratory medications and supplemental oxygen vs the no-BPD or the BPD groups. At 4, 8 and 36 months of age, more children in the BPD with chronic oxygen dependency group had post-neonatal chronic lung disease (PNCLD) than children in the other groups, but at 36 months the difference was significant only for the BPD with chronic oxygen dependency vs no-BPD group (P<0.001).
At 36 months, children diagnosed with BPD with chronic oxygen dependency at NICU discharge were more likely to need respiratory medications and supplemental oxygen in the previous 12 months, as compared with no-BPD or BPD groups. They were also more likely to require frequent physician visits and have PNCLD at 3 years, as compared with the no-BPD group.
Hydrocarbon cracking and carbon contamination of optical elements in soft X-ray spectrometers and synchrotron radiation beamlines is a severe problem. Carbon contamination seriously affects the ...optics performance. In the present work, an Nd:YAG laser providing 2mJ of pulse energy and 100ns of pulse duration has been used for carbon cleaning experiments. The laser cleaning is a non-contact, accurate, efficient and safe process. A surface area of 48cm2 having ∼20nm thick carbon layer on gold surface has been removed with six number of laser passes and with 80% laser spot overlapping without any change in surface roughness of the underneath gold film. Effect of laser beam on gold film after carbon removal has been analyzed using X-ray photoelectron spectroscopy, soft X-ray reflectivity techniques. Atomic force microscopy was used to analyze surface morphology before and after laser cleaning process. Power spectral density function was calculated over large frequency range of 10−1 to 10−4nm−1 to understand topographic data.
Summary The palm has proved to be the most satisfactory domor site for the defects of the palm, fingers and sole of the foot. Our results were superior by this method—over the other methods we had ...tried.
Macrophomina phaseolina (Tassi) Goid., causing charcoal rot on many economically valuable crops, is the most destructive soil borne plant pathogen in Indian arid regions. Combining Brassica ...amendments like mustard residues or oil cake with one summer irrigation was found effective as an alternative to expensive soil solarization in reducing incidence of Macrophomina induced diseases. Efficiency of Brassicas was improved when these were incorporated after prolonged exposure of pathogen-infested soil to dry summer heat amounting to sub lethal heating, which exerted a weakening effect. Mustard oil cake though found more effective than mustard residues could not find acceptance in the resource deficient farming community of the region due to high initial cost. Large differences in effectiveness between different crucifer species have been found in control of soil borne plant pathogens. It was, therefore, thought worthwhile to examine whether by supplementing a small dose of other crucifers can improve the efficiency of mustard residues in pathogen control. This work reports the results of study on interactive effects of sub lethal heating and cruciferous residues on survival of M. phaseolina propagules. Utilizing a typical hot arid environment, in a field experiment conducted during summer days, combined effect of weakened pathogenic propagules and cruciferous amendments (mustard, cauliflower, Eruca and mustard oil cake) was ascertained in improving the control of M. phaseolina. In this study, improvement in mortality of Macrophomina by 6.9-9.4% was achieved merely by extending summer exposure time of pathogen infested soil from 30 to 60 days to attain discernible weakening effect prior to incorporation of amendments. Supplementing economic dose of cauliflower residues or mustard oil cake (0.04%) with mustard residues (0.18%) augmented reduction by 10.7-11.6% compared to mustard residues alone after completion of the experiment. Demonstration of this soil disinfestation strategy at growers’ field has produced encouraging results.
We report the results of growth kinetics of oxidation process on niobium thin film surfaces exposed to air at room temperature by using a surface sensitive non-destructive X-ray reflectivity ...technique. The oxidation process follows a modified Cabrera–Mott model of thin films. We have shown that the oxide growth is limited by the internal field due to the contact potential which develops during the initial stage of oxidation. The calculated contact potential for 100 and 230
Å thick films is 0.81
±
0.14 and 1.20
±
0.11
V respectively. We report that 40% increase in the contact potential increases the growth rate for the first few mono layers of Nb
2O
5 from ∼2.18 to ∼2790
Å/s. The growth rates of oxidation on these samples become similar after the oxide thicknesses of ∼25
Å are reached. We report on the basis of our studies that a protective layer should be grown in situ to avoid oxidation of Nb thin film surface of Nb/Cu cavities.
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