Junction Model Research Articles

2D Modeling of Solar Cell Radial Junction: Study of Carriers Charge Density and Photocurrent Density in Static Mode under Monochromatic Illumination

A theoretical study of a polysilicon solar cell with a radial junction in static regime under monochromatic illumination is presented in this paper. The junction radial solar cell geometry is illustrated and described. The carriers’ diffusion equation is established and solved under quasi-neutral base assumption with boundaries conditions and Bessel equations. New analytical expressions of electrons and holes density and photocurrent are found. The wavelength and structural parameters (base radius, emitter thickness) influences on charge carriers density and photocurrent are shown and examined.

Hybrid Nb/Al/Ba0.5K0.5Fe2As2 sandwich Josephson junctions

We fabricated hybrid Josephson junctions between a Ba0.5K0.5Fe2As2 (BKFA) single crystal and the conventional superconductor Nb with normal metal Al as the barrier. An in situ process was used to create clean BKFA/Al/Nb interfaces. Current transport is along the c-axis of BKFA. The current–voltage characteristics are slightly hysteretic at low temperatures. Except for some features indicative of resonant modes the shape of the current–voltage characteristics can be well described by the resistively and capacitvely shunted junction (RCSJ) model, with a product of the Josephson critical current and the normal state resistance of the junction exceeding 180 μV at low temperatures. The temperature dependence of the Josephson current is linear for temperatures down to 2 K. Under 40 GHz microwave irradiation integer Shapiro steps are observed. The power dependence of the Shapiro step-height is in good agreement with RCSJ simulations. Possible relations of our data with the symmetry of the superconducting order parameter of BKFA are discussed.

On capacitance–voltage characteristics of non-hydrogenated amorphous silicon/crystalline silicon heterojunctions for solar-cell applications

This work presents the performance of a HIT (Heterojunction with Intrinsic Thin layer) solar cell which was fabricated for the first time in the Advanced Electronics Laboratory of Batna 2 University by sputtering silicon on p-type crystalline silicon substrate. This initial effort was a tentative to learn about the fabrication technique and the control of the deposition parameters involved in the fabrication process. Preliminary capacitance voltage measurements confirm an abrupt junction model in consistence with the earlier published data. A junction depth of 0.58 µm and a diffusion voltage of 1.65 V were obtained. A defect density in the gap of non-hydrogenated amorphous silicon of 6.93 1014 cm−3 was computed indicating the presence of defect states.

Integrating Manipulatives and Animations to Visualize Holliday Junctions

The complex molecular architecture of Holliday junctions is often challenging for undergraduate biochemistry students to conceptualize. In particular, they have difficulty translating from two-dimensional, linear representations shown in textbooks to the atomic-resolution DNA structures. This challenge impedes their comprehension of the mechanisms by which proteins are able to bind, hydrolyze, and re-ligate the component DNA strands. We have developed an affordable, portable Holliday junction model using colored chenille stems (a.k.a. pipe cleaners) that students use to first visualize the DNA structures within Holliday junctions, and relate those structures to the static two-dimensional representations in textbooks. To fully integrate the linear depictions with the three-dimensional models, students then watch an online animated movie that models the dynamics of Holliday junction resolution. Students then use those models to work problem sets that include questions about double-stranded break repair, mating-type switching, and genetic crossover. The implementation of these personal manipulative models for each student has notably improved student comprehension of the molecular mechanism of homologous recombination. <em>Primary image:&nbsp;</em>Representations of Holliday Junctions. Top row: a conventional line schematic of a Holliday junction, in which there are four heteroduplexes of double-stranded DNA, shown beside a cartoon representation of a Holliday junction solved by x-ray crystallography (PDB: 1DCW). Bottom row: a chenille-stem manipulative, which can be interconverted between the conventional line schematic and the open-cruciform structure that are depicted in the top row.

Modeling dislocation-related leakage currents in GaN p-n diodes

Finite element analysis software was used to model and visualize two p-n junction models: one with a single threading dislocation (TD) and a control model without a dislocation. TDs are modeled as a Gaussian distribution of trap states with an FWHM of 5 nm localized around the r=0 line in a cylindrical coordination such that the linear trap state density was 1 trap/c-translation; this model allows the cylindrical symmetry of the c-plane GaN crystal orientation to be utilized to avoid more computationally intensive 3D models. It was discovered that the interaction of the charged dislocation region with the p-n junction had many notable effects. At zero bias, it was observed that the depletion region width (using the Depletion Approximation) and the maximum electric field were markedly reduced near the dislocation line. More significantly, an asymmetric reduction in the diffusion barrier for electrons (Vbieff=3.03eV) and holes (Vbieff=0.81eV) was observed due to the asymmetric nature of the dislocation band bending related to the doping. The asymmetric reductions in diffusion barriers persisted into VA=2.4V leakage case where asymmetric current profiles for electrons and holes were also observed. Lastly, the diffusion barrier reduction resulted in an additional Shockley-Read-Hall nonradiative recombination leakage caused by a high np-product and trap state density near the intersection of the dislocation with the junction.

Evaluation of abnormal styloid anatomy as a cause of internal jugular vein compression using a 3D-printed model: a laboratory investigation

This study used a 3-dimensional (3D) craniocervical junction model of styloidogenic jugular venous compression (SJVC) syndrome to simulate and evaluate intracranial pressure (ICP) after internal jugular vein (IJV) compression by an elongated styloid process during axial rotation. The 3D-printed model created using data from an SJVC-syndrome patient included an articulating occipital-cervical junction, simplified arteriovenous system, gauge to measure simulated ICP, fixed obstruction simulating left-sided venous occlusion, and right-sided vascular tubing to simulate IJV compression. The model was rotated axially to its extreme right and left; maximum degree of motion and pressure were recorded for 3 cycles. Measurements were repeated after styloid resection in 25% increments. The extreme right rotation (11°) of the intact styloid condition yielded a mean pressure of 15.34 ± 2.85 mmHg. After 25% styloid resection, extreme rotation (11°) yielded 13.96 ± 2.88 mmHg. After 50%, extreme rotation increased to 16° yielding 17.41 ± 3.52 mmHg; 11° rotation was 2.76 ± 1.96 mmHg. After 75%, extreme rotation increased to 19° yielding −0.86 ± 1.08 mmHg; 16° and 11° rotation yielded −0.69 ± 1.19 and −0.86 ± 1.08 mmHg, respectively. After 100%, extreme rotation to 19° yielded −1.21 ± 0.60 mmHg; 16° and 11° rotation yielded −0.34 ± 0.30 and 0.00 ± 0.00 mmHg, respectively. Extreme left rotations (11°) yielded mean pressures of −0.17 ± 0.00 (intact), −0.17 ± 0.30 (25%), 2.24 ± 0.79 (50%), 0.34 ± 0.30 (75%), and 0.17 ± 0.30 mmHg (100%). Simulated ICP increased proportionally to maximum ipsilateral axial rotation, and was highest after 50% styloid resection. Contralateral axial rotation did not increase pressure. IJV compression was relieved at 75% resection, suggesting that partial (75%) or complete styloidectomy is a potentially efficacious treatment for SJVC syndrome.

Quantum oscillations in a two-dimensional electron system under low-frequency microwave irradiation

We study the magnetoresistance of an ultrahigh mobility GaAs/AlGaAs two-dimensional electron sample in a weak magnetic field under low-frequency (f < 20 GHz) microwave (MW) irradiation. We observe that with decreasing MW frequency, microwave induced resistance oscillations (MIRO) damp and multi-photon processes become dominant. At very low MW frequency (f < 4 GHz), MIRO disappears gradually and a new SdH-like oscillation develops. The analysis indicates that the new oscillation may originate from alternating Hall-field induced resistance oscillations (ac-HIRO), or can be viewed as a multi-photon process of MIRO in low MW frequency limit. Our findings bridge the non-equilibrium states of MIRO and HIRO, which can be brought into a frame of quantum tunneling junction model.

Mathematical model of adhesion junction of layers during coextrusion

Nine theories of polymer adhesion during coextrusion are researched. Two approaches to describing adhesion are presented – thermodynamic and molecular-kinetic ones. The factors, determining the durability of adhesion junction, are analyzed. The stages of adhesion connection formation are presented. The adhesion junction emergence model as a result of intermolecular interaction is described. As a result of calculations the following dependencies are got: the dependence of ply separation energy on the contact length of polyisobutylene adhesion junction of different molecular weight, the dependence of ply separation energy on molecular weight of polyisobutylene adhesion junctions got during different time, the dependence of adhesion durability on squared difference of polymer solubility parameters, the dependence of interdiffused zone width in the time.

Markovian treatment of non-Markovian dynamics of open Fermionic systems

We show that an open fermionic system coupled to a continuous environment with unitary system-environment evolution can be exactly mapped onto an auxiliary system consisting of the physical fermion system and a set of discrete fermionic modes subject to non-unitary Lindblad-type system-modes evolution in such a way that reduced dynamics of the fermionic system in the two cases are the same. Conditions for equivalence of reduced dynamics in the two systems are identified and a proof is presented. Our study extends recent work on Bose systems (Tamascelli et al 2018 Phys. Rev. Lett. 120 030402) to the case of open quantum Fermi systems and to multi-time correlation functions. Numerical simulations within a generic junction model are presented for illustration.

Propagation of short current pulses in Josephson transition line and ultrafast qubit control

The results of the study of the impact of single-quantum magnetic flux pulses moving along the Josephson transmission lines (JTL) on the dynamics of states of qubits magnetically coupled with such lines are presented. The JTL dynamics was calculated in the frame of resistively shunted junction model with different damping coefficients. This allowed us to find the form of control current pulses (fluxon) acting on a superconducting qubit. Numerical simulations of the simplest logic operations with superconducting qubit due to calculated fluxon impact are presented.

Three-Dimensional-Printed Model-Assisted Management of Craniovertebral Junction Abnormalities: An Institutional Experience with Literature Review.

Study DesignProspective study.PurposeTo evaluate the utility and limitations of using three-dimensional (3D)-printed models for the management of craniovertebral (CV) junction abnormalities.Overview of LiteratureIn comparison to other bony and vascular anomalies, CV junction abnormalities are difficult to treat. For cases of irreducible atlantoaxial dislocation (AAD), posterior reduction and stabilization have replaced anterior decompression as the standard management protocol. The use of 3D models, such as those described herein, can provide surgeons with in-depth knowledge of the vertebral artery course and bony anomalies associated with CV junction abnormalities.MethodsClinical and radiological features of 18 patients with CV junction abnormalities were analyzed between March 2017 and February 2019 at Sawai Man Singh Medical College, Jaipur, India. Dynamic computed tomography (CT) of the CV junction and CT angiographies of the neck with respect to the vertebral artery course at the C1–C2 joints were obtained and studied. Customized 3D models of the CV junction were then made based on the CT data, and rehearsal of the surgical procedure was performed using the 3D model one day prior to performing the actual procedure.ResultsSeventeen patients had congenital-type AAD, whereas one patient had posttraumatic AAD. Improvements in neck pain and myelopathy were seen in all patients at the follow-up, as analyzed using the Visual Analog Scale and the Japanese Orthopedic Association Scale score, respectively. There were no cases of malpositioning of screws or any direct vertebral artery injury, although in one patient, the distal flow in the dominant vertebral artery was cut off as it got compressed between the bony arch and the screw head.ConclusionsCompared to computer-generated images, 3D-printed models are a more practical approach for dealing with complex CV junction abnormalities. They provide surgeons with deep insights into the complex bony anomalies as well as variations in the vertebral artery courses, thereby improving surgical outcomes.

Probing the minigap in topological insulator-based Josephson junctions under radio frequency irradiation**Project supported by the National Basic Research Program of China (Grant Nos. 2016YFA0300601, 2017YFA0304700, and 2015CB921402), the National Natural Science Foundation China (Grant Nos. 11527806, 91221203, 11174357, 91421303, and 11774405), and the Strategic Priority Research Program B of the Chinese Academy of Sciences (Grant Nos. XDB07010100 and XDB28000000), and

Recently, a contact-resistance-measurement method was developed to detect the minigap, hence the Andreev bound states (ABSs), in Josephson junctions constructed on the surface of three-dimensional topological insulators (3D TIs). In this work, we further generalize that method to the circumstance with radio frequency (rf) irradiation. We find that with the increase of the rf power, the measured minigap becomes broadened and extends to higher energies in a way similar to the rf power dependence of the outer border of the Shapiro step region. We show that the corresponding data of contact resistance under rf irradiation can be well interpreted by using the resistively shunted Josephson junction (RSJ) model and the Blonder–Tinkham–Klapwijk (BTK) theory. Our findings could be useful when using the contact-resistance-measurement method to study the Majorana-related physics in topological insulator-based Josephson junctions under rf irradiation.

Novel neuromuscular junction model in 2D and 3D myotubes co-cultured with induced pluripotent stem cell-derived motor neurons

Motor neurons differentiated from induced pluripotent stem (iPS) cells have attracted attention for use in the construction of drug screening systems for neuronal diseases, such as amyotrophic lateral sclerosis. However, conventional drug screening systems using 2-dimensional (2D) cultures of iPS cell-derived motor neurons often evaluate the cell survival rate, morphological changes in the cells and/or gene expression analysis, and these parameters do not always reflect the actual functions of motor neurons, i.e., the induction of muscle contractions. In the present study, we developed a neuromuscular junction model comprising motor neurons and myotubes, which were differentiated from iPS cells and C2C12 myoblasts, respectively. Using this model, the contractile activity and force generation of the myotubes via the neuromuscular junction were successfully measured in both two- and three-dimensional (3D) cell culture systems. The results suggested that this neuromuscular junction model can be used to construct a drug candidate screening system for neuronal diseases.

Mathematical Modeling and Simulation of Junction less Dual Material Double Gate MOSFET with Various Work Functions

In view of the 2-Dimensional game plan of Poisson's condition, a material science-based model of Double Gate Dual Material Junction less (DGDMJNL) Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET) is made. The advantages of different work capacities connected to the metals in DMDGJNL MOSFET are exhibited and the potential at the inside and qualities of the electric field is uncovered. The proposed model exhibits explicitly demonstrates the effect of the work in electrostatic potential and electric field. It is exhibited that the execution of DMDGJNL MOSFET can be changed by adjusting the channel length extents of control door and shield entryway. The model is assessed by its figured results and those got from a 3D TCAD test system for numerical outcomes.

A fast MoM solver for wire‐to‐surface junctions in layered uniaxial media

AbstractWire‐to‐surface structures in layered uniaxial media are of great importance in practical applications. This paper presents the essential procedures to build a fast method of moments (MoM) solver for modeling wire‐to‐surface structures in layered uniaxial media. These procedures include the modeling of junctions, accelerated evaluation, and efficient interpolation of the layered media Green's function (LMGF), and thin‐wire modeling in layered uniaxial media. Three numerical examples are presented to demonstrate the accuracy and efficiency of our approach.

Adapter sleeves are essential for ceramic heads in hip revision surgery

BackgroundRemoving a head during isolated acetabular revision surgery can cause damage to the stem taper surface from extraction tool contact. Implanting a ceramic head on the damaged stem taper might elevate the fracture risk, which can be mitigated with the use of titanium adapter sleeves. The aim of this study was to investigate whether the improved fracture strength of modern generation ceramic heads allows the direct implantation on damaged stem tapers without an adapter sleeve. MethodsFinite element models of taper junctions with and without adapter sleeve were generated. Different stem taper damages were modelled to investigate the influence on the ceramic head fracture load under axial compression. FindingsHeads without adapter sleeves exhibited slightly higher or equal fracture strengths compared with sleeved heads for most scenarios. However, a small metal elevation on the stem taper caused a drastic decrease of the fracture strength if no adapter sleeve was used (−96%). The sleeved head was not influenced by the metal elevation damage. InterpretationAdapter sleeves are essential to ensure patient safety and prosthesis longevity whenever implanting ceramic heads on used stem tapers.

Charge Carrier Dynamics in Electron-Transport-Layer-Free Perovskite Solar Cells

Better understanding of the carrier dynamics process in electron-transport-layer (ETL)-free perovskite solar cells (PSCs) enables further exploration of the perovskite potential and corresponding device structure design. Herein, an ETL-free perovskite/transparent conductive film SnO2:F(FTO) contact with different perovskite thicknesses illuminated by varied light intensities were investigated by scanning probe microscopy technology. Strong charge transfer occurs at the perovskite/FTO contact, evidenced by the variations of both the surface contact potential and local current value. Mott–Schottky analysis based on capacitance–voltage measurements suggests that the interface property of the perovskite/FTO contact is similar to that of the perovskite/TiO2/FTO structure, making it ideal for fabricating ETL-free PSCs. The cross-sectional surface potential drop was found to be mainly located at the CH3NH3PbI3/FTO heterojunction, suggesting a single diode junction in the ETL-free PSCs. Furthermore, a single-side abrupt p–n++ junction model is employed to illustrate the energy level alignment at the perovskite/FTO contact. This study will be helpful for understanding the carrier dynamics process and thus achieving high device efficiency in the ETL-free PSCs.

Acetone sensing behavior of p-SmFeO3/n-ZnO nanocomposite synthesized by thermal treatment method

In this paper, the synthesis, characterization and sensing properties of SmFeO3/ZnO nanocomposite synthesized by the thermal treatment method, is reported. The morphological and microstructural characteristics of the synthesized composite nanopowders and single SmFeO3 and ZnO components, were analyzed by Scanning Electron Microscopy-Electron Dispersive X-ray (SEM-EDX), X-ray diffraction (XRD), Fourier Transform-Infrared (FT-IR) spectroscopy and Photoluminscence (PL). Characterization analyses revealed that SmFeO3/ZnO nanocomposite sample is composed of individual SmFeO3 nanoparticles in the orthorhombic phase and ZnO in the wurzite phase. However, emission characteristics in the photoluminescence spectra suggest a high interaction degree between the components of composite. The gas-sensing characteristics of the nanopowders were evaluated in the detection of acetone at low concentration in air. The very high acetone sensitivities of SmFeO3/ZnO nanocomposite sensor was discussed in the framework of the p-n junctions model.

Electrical synapses interconnecting axons revealed in the optic nerve head - a novel model of gap junctions' involvement in optic nerve function.

PurposeTo characterize newly discovered electrical synapses, formed by connexin (Cx) 36 and 45, between neighbouring axons within the optic nerve head.MethodsTwenty‐five Wistar rats were killed by CO 2 inhalation. Proximal and distal optic nerve (ON) stumps were collected and processed for immunostainings, electron microscopy (EM) with immunogold labelling, PCR and Western blots (WB). Additional 15 animals were deeply anaesthetized, and flash visual evoked potentials (fVEP) after retrobulbar injection of saline (negative control) or 100 μ m meclofenamic acid solution (gap junctions’ blocker) were recorded. Human paraffin cross‐sections of eyeballs for immunostainings were obtained from the Human Eye Biobank for Research.ResultsImmunostainings of both rat and human ON revealed the presence of Cx45 and 36 colocalizing with β3‐tubulin, but not with glial fibrillary acidic protein (GFAP). In WB, Cx36 content in optic nerve was approximately halved when compared with retina (0.58 ± 0.005 in proximal stump and 0.44 ± 0.02 in distal stump), Cx45 showed higher levels (0.68 ± 0.01 in proximal stump and 0.9 ± 0.07 in distal stump). In immunogold‐EM of optic nerve sections, we found electric synapses (formed mostly by Cx45) directly coupling neighbouring axons. In fVEP, blocking of gap junctions with meclofenamic acid resulted in significant prolongation of the latency of P1 wave up to 160% after 30 min (p < 0.001).ConclusionsOptic nerve (ON) axons are equipped with electrical synapses composed of neuronal connexins, especially Cx45, creating direct morphological and functional connections between each other. This finding could have substantial implications for understanding of the pathogenesis of various optic neuropathies and identifies a new potential target for a therapeutic approach.

A Two Dimensional Tunneling Resistance Transmission Line Model for Nanoscale Parallel Electrical Contacts

Contact resistance and current crowding are important to nanoscale electrical contacts. In this paper, we present a self-consistent model to characterize partially overlapped parallel contacts with varying specific contact resistivity along the contact length. For parallel tunneling contacts formed between contacting members separated by a thin insulating gap, we examine the local voltage-dependent variation of potential barrier height and tunneling current along the contact length, by solving the lumped circuit transmission line model (TLM) equations coupled with the tunneling current self consistently. The current and voltage distribution along the parallel tunneling contacts and their overall contact resistance are analyzed in detail, for various input voltage, electrical contact dimension, and material properties (i.e. work function, sheet resistance of the contact members, and permittivity of the insulating layer). It is found the existing one-dimensional (1D) tunneling junction models become less reliable when the tunneling layer thickness becomes smaller or the applied voltage becomes larger. In these regimes, the proposed self-consistent model may provide a more accurate evaluation of the parallel tunneling contacts. For the special case of constant ohmic specific contact resistivity along the contact length, our theory has been spot-checked with finite element method (FEM) based numerical simulations. This work provides insights on the design, and potential engineering, of nanoscale electrical contacts with controlled current distribution and contact resistance via engineered spatially varying contact layer properties and geometry.