Composition of Carbon Clusters in Implanted Silicon Using Atom Probe Tomography

Atom probe tomography was employed to observe and derive the composition of carbon clusters in implanted silicon. This value, which is of interest to the microelectronic industry when considering ion implantation defects, was estimated not to exceed 2 at%. This measurement has been done by fitting the distribution of first nearest neighbor distances between monoatomic carbon ions (C+ and C2+). Carbon quantification has been considerably improved through the detection of molecular ions, using lower electric field conditions as well as equal proportions of 12C and 13C. In these conditions and using another quantification method, we have shown that the carbon content in clusters approaches 50 at%. This result very likely indicates that clusters are nuclei of the SiC phase.

Preconditioning with Near-Infrared Irradiation to Enhance the Irreversible Electroporation Efficiency in HeLa Cells

Irreversible electroporation (IRE) has gained attention for ablation owing to fewer side effects and fast recovery. However, a high current from the applied high voltage can cause muscle contraction. Adding cationic molecules has been introduced to lower electric field strengths and enhance IRE outcomes by inducing hyperpolarization across the cell plasma membrane. Near-infrared light (NIR) has recently been reported to induce hyperpolarization across membranes in a mode-dependent manner. In this study, we performed IRE in HeLa cells after exposure to 810 nm NIR irradiation. Preconditioning with NIR of 3 J/cm2 induced changes in membrane potential, resulting in approximately two times enhancement of apoptosis by IRE. The apoptotic signals were governed by the presence of BAX and p53 and were not related to excess oxidative stress. NIR has better spatial and temporal distribution control than chemicals and, therefore, can enhance the spatial selectivity and reduce the side effects of IRE treatment. These results can be used to enhance the clinical outcomes of IRE.

Study on Electric Field Modulation and Avalanche Enhancement of SiC/GaN IMPATT Diode

This paper proposes a 6H-materials silicon carbide (SiC)/gallium nitride (GaN) heterogeneous p-n structure to replace the GaN homogenous p-n junction to manufacture an impact-ionization-avalanche-transit-time (IMPATT) diode, and the performance of this 6H-SiC/GaN heterojunction single-drift-region (SDR) IMPATT diode is simulated at frequencies above 100 GHz. The performance parameters of the studied device were simulated and compared with the conventional GaN p-n IMPATT diode. The results show that the p-SiC/n-GaN IMPATT performance is significantly improved, and this is reflected in the enhanced characteristics in terms of operating frequency, rf power, and dc-rf conversion efficiency by the two mechanisms. One such characteristic that the new structure has an excessive avalanche injection of electrons in the p-type SiC region owing to the ionization characteristics of the SiC material, while another is a lower electric field distribution in the drift region, which can induce a higher electron velocity and larger current in the structure. The work provides a reference to obtain a deeper understanding of the mechanism and design of IMPATT devices based on wide-bandgap semiconductor materials.

Evaluation of Pulsed Electric Field Polyphenol Extraction from Vitis vinifera, Sideritis scardica and Crocus sativus

This study exploited the application of pulsed electric field (PEF) on the recovery of polyphenols from aerial parts of Sideritis scardica, tepals of Crocus sativus, and fruits of Vitis vinifera. Short pulses of 10 μs in a period of 1 ms were applied to the plant material, while different electric field intensities, 1.2 to 2.0 kV/cm were tested to optimize the procedure. The content in total polyphenols and the polyphenolic profile of the plant extracts were evaluated. Along with PEF samples, control samples were prepared for comparison. PEF treatment enhanced the recovery in total polyphenols for all the three plants examined. A significant increase was noticed in each plant tested and PEF condition applied, though lower electric field intensities up to 1.4 kV/cm proved to be more effective. Under the optimum electric field intensities, 1.4 kV/cm for V. vinifera and 1.2 kV/cm for S. scardica and C. sativus, increases of 49.15%, 35.25%, and 44.36% in total polyphenol content, respectively, were achieved. Additionally, an 85% increase of quercetin 3-rutinoside for V. vinifera, a 56% of apigenin 7-O-glucoside for S. scardica, and a 64% increase for kaempferol 3-O-glucoside for C. sativus were obtained.

Ion-Induced Anomalous Charge Collection Mechanisms in SiC Schottky Barrier Diodes

The charge induced in SiC-SBDs with different epi-layer thicknesses by ion incidence was measured to understand the mechanism of heavy-ion-induced anomalous charge collection in SiC-SBDs. SiC SBD of which epitaxial-layer thicknesses is close to ion range show larger anomalous charge collection than SBD with thicker epi-layer although the former one has lower electric field than the later one. The gains of collected charge from the SBDs suggest that the impact ionization under 0.16 - 0.18 MV/cm of the static electric field in depletion layer is not dominant mechanisms for the anomalous charge collection. It is suggested that the epitaxial-layer thickness and ion-induced transient high electric field are key to understand the anomalous charge collection mechanisms in SBDs.

Optical and Electron Emission Properties of h-BN Films Codoped with Mg and O Atoms

Films of hexagonal BN (h-BN) codoped with Mg and O atoms were grown on n-type Si and quartz substrates heated at 500 °C by sputtering targets consisting of h-BN and MgO powders. An absorption is seen at a wavelength < 400 nm for h-BN films prepared in an Ar atmosphere. In contrast, films prepared from the target containing 0.25 mol% MgO in an atmosphere of Ar + 1% O2 shows an absorption at a wavelength < 260 nm and an electron field emission at a lower electric field of 3.6 V/μm.

Growth and Characterization of Single Crystalline Bi4Ge3O12Fibers for Electrooptic High Voltage Sensors

The micro-pulling-down technique for crystalline fiber growth is employed to grow fibers and thin rods of bismuth germanate, Bi4Ge3O12(BGO), for use in electrooptic high voltage sensors. The motivation is the growth of fibers that are considerably longer than the typical lengths (100–250 mm) that are achieved by more conventional growth techniques like the Czochralski technique. At a given voltage (several hundred kilovolts in high voltage substation applications) longer sensors result in lower electric field strengths and therefore more compact and simpler electric insulation. BGO samples with lengths up to 850 mm and thicknesses from 300 μm to 3 mm were grown. Particular challenges in the growth of BGO fibers are addressed. The relevant optical properties of the fibers are characterized, and the electrooptic response is investigated at voltages up to .