Hybrid Junction Research Articles

Emulating bianisotropic coupling through coherent illumination

One of the main advantages of reciprocal bianisotropic metasurfaces is their capability to produce asymmetric scattering depending from which side they are illuminated and on the handedness of circularly polarized illuminations. For most applications, these metasurfaces are designed for illumination by a single source at a time. The resulting bianisotropic metasurface has a specific and usually complex geometrical structure that ensures the expected scattering produced under various illuminations. Here we show that geometrical asymmetry of metasurfaces can be emulated by using non-bianisotropic layers in presence of coherent illumination, which allows us to replicate and optically control the desired asymmetric scattering and chirality effects. In particular, the concept is developed on an example of emulating asymmetric scattering needed to create a 180$^\circ$ hybrid junction for plane waves. We show that this device can be realized either using a bianisotropic metasurface or a set of simple sheets with electric response under simultaneous illumination by two coherent waves.

Advances in hybrid junction solar cells

Advances in hybrid junction solar cells

Delta- T noise for fractional quantum Hall states at different filling factor

The current fluctuations due to a temperature bias, i.e. the delta-$T$ noise, allow one to access properties of strongly interacting systems which cannot be addressed by the usual voltage-induced noise. In this work, we study the full delta-$T$ noise between two different fractional quantum Hall edge states, with filling factors $(\nu_L,\nu_R)$ in the Laughlin sequence, coupled through a quantum point contact and connected to two reservoirs at different temperatures. We are able to solve exactly the problem for all couplings and for any set of temperatures in the specific case of an hybrid junction $(1/3,1)$. Moreover, we derive a universal analytical expression which connects the delta-$T$ noise to the equilibrium one valid for all generic pairs $(\nu_L,\nu_R)$ up to the first order in the temperature mismatch. We expect that the linear term can be accessible in nowadays experimental set-ups. We describe the two opposite coupling regimes focusing on the strong one which correspond to a non-trivial situation. Our analysis on delta-$T$ noise allows us to better understand the transport properties of strongly interacting systems and to move toward more involved investigation concerning the statistics and scaling dimension of their emergent excitations.

Microwave spectroscopy of Andreev states in InAs nanowire-based hybrid junctions using a flip-chip layout

Josephson junctions based on semiconductor nanowires are potential building blocks for electrically tunable qubit structures, e.g., the gatemon or the Andreev qubit. However, an actual realization requires the thorough investigation of the intrinsic excitation spectrum. Here, we demonstrate the fabrication of low-loss superconducting microwave circuits that combine high quality factors with a well-controlled gate architecture by utilizing a flip-chip approach. This platform is then used to perform single-tone and two-tone experiments on Andreev states in in-situ grown InAs/Al core/half-shell nanowires with shadow mask defined Josephson junctions. In gate-controlled and flux-biased spectroscopic measurements we find clear signatures of single quasiparticle as well as quasiparticle pair transitions between discrete Andreev bound states mediated by photon-absorption. Our experimental findings are supported by simulations that show that the junction resides in the intermediate channel length regime.

Synchronous enhancement of responsivity, response time and, spectral range in solution processed CdS photodetector upon modification with PEDOT:PSS

Solution processed photodetectors with high responsivities and simple fabrication schemes are high on demand for variety of emerging opto-electronic applications. However, these devices suffer from sluggish response and recovery times. In this work, we demonstrate the simultaneous enhancement of the responsivity, response time and spectral range of detection in a solution-processed device based on organic/inorganic hybrid junction. A solution-processed flexible CdS photodetector is fabricated using a facile and economical chemical bath deposition technique. The fabricated pristine-CdS device exhibits responsivity and response time of 50 mA/W and 5.4 s. The resultant device exhibits enhanced responsivity and response time of around 740 mA/W and 0.6 s, respectively, upon modification with the PEDOT:PSS conducting polymer. These values of PEDOT-modified device are one order larger than pristine-CdS detector. Further, PEDOT:PSS modification also extends the responsivity of the device from UV-Vis to NIR spectra. NIR responsivity in the hybrid device, is imputed to the photothermal property of the PEDOT:PSS layer. Thus, the overall device spectral response is accredited to the simultaneous existence of photoelectric and photo-thermal phenomena. The observed responsivity and faster response time is ascribed primarily to the built-in potential at interface of CdS-PEDOT:PSS, which not only facilitates efficient separation of photo carriers but also leads to a reduction in the recombination of excitons. Given the simple approach and excellent enhancement in the device performance, the idea demonstrated here could be useful to design high performance opto-electronic device based on solution-processed techniques.

Preparation of Hybrid Junction Light Emitting Device from Cadmium Sulphite Quantum dot/ poly-TPD Junction

Stratums of ITO/TPD:PMMA/CdS/Alq3/Al were used to make the hybrid nanoparticles light emitting diode (NPs-LED), which were created using the phase segregation method and the spin coating procedure. Light-generating NPs-LED hybrid device is composed of 3 stratums stacked in a certain order on an Indium tin oxide(ITO) substrate made of transparent conducting oxide. The first stratum was (N, N'-bis (3-methylphenyl)-N, N'-bis (phenyl) benzidine) (TPD) polymer, and polymethyl methacrylate (PMMA) polymer. Cadmium Sulphite (CdS) is the second stratum, while Tris (8-hydroxyquinolinato) aluminum (Alq3) is the last stratum, which is one of the materials used as electron injector stratums.
 Various bias voltages (28, 30, and 32V) were used to examine the electroluminescence (EL) of NPs-LEDs at room temperature, depending on the CIE 1931 color spaces, `light was created at 32V, whereas blue light was generated at 28V. The transmission between sub levels in the energy gap of CdS NPs (surface state). Voltages are controlling the current change, and the knee voltage is 6.6 V, as seen by the current – voltage (I-V) distinctive. EL spectrum demonstrates a broadband emission spanning 300 nm to 700 nm. Finally, it is discovered that the correlated color temperature (CCT) is about (7450 to 11820k).

Pure crossed Andreev reflection assisted transverse valley currents in α−T3 lattices

We propose a novel method for the generation of the transverse valley currents, which is based on the pure crossed Andreev reflection (pCAR) in the superconducting hybrid junctions composed of the gapped $\alpha-\mathcal{T}_3$ lattices with ferromagnet-induced exchange interaction. The angle-resolved pCAR probability is asymmetric for a given valley, resulting in the transverse valley currents with zero net charge. This pCAR assisted charge-valley conversion is highly efficient with the valley Hall angle reaching an order of unity, suggesting potential applications for valleytronic devices.

High responsivity self-powered flexible broadband photodetector based on hybrid Selenium-PEDOT:PSS junction

Hybrid organic-inorganic composites offer solution processability and ease to construct opto-electronic devices with diverse functionalities, which are desirable for applications like flexible and printed electronics. Trigonal Selenium (t-Se) has been recently investigated for photodetector application, owing to its inherent superior optical properties such as high absorption coefficient and photoconductivity. However, most of the reported Selenium photodetectors use vapor transport based device fabrication techniques which require controlled environments and face scalability issues. In this work, high-performance photodetector based on Selenium-PEDOT:PSS hybrid junction is demonstrated using a facile sonication assisted mechanical mixing and drop-casting technique. XRD and Raman analysis reveals the existence of Selenium in trigonal crystal structure and FE-SEM images show clustered nanoparticles. Selenium is mixed with PEDOT:PSS to form bulk heterojunction, which enhances the electron-hole pair separation efficiency and results in improved device responsivity. Also, due to the favorable band offset between Selenium and PEDOT:PSS which results in built-in field, the photodetector operates in self-biased mode. The device exhibits broad spectral response in UV–Vis–NIR range with responsivities of 0.56 A/W, 66 mA/W and 1.363 A/W at 315 nm, 620 nm and 820 nm, respectively. Response times of 7.7 s, 9.4 s and 6.4 s and external quantum efficiencies (EQE) of 192.58%, 13.25% and 206.55% are obtained for UV, Vis and NIR spectra respectively. Further to validate the robustness, the device is subjected to multiple bending cycles (∼2500) and minimal degradation in performance is observed. Given the simple device architecture and facile device fabrication scheme, this work would enable promising approach for high performance flexible photodetectors. • Selenium, possesses high absorption co-efficient and high photoconductivity with optical bandgap of 1.2–1.5 eV. • However, t-Se has been less explored for photodetector applications. • This work reports a solution-processed hybrid-heterojunction based on Se-PEDOT:PSS for photodetection. • The detector exhibits spectral response from UV–Vis to NIR and significant performance at zero bias condition.

Hybrid Platforms of Silicon Nanowires and Carbon Nanotubes in an Ionic Liquid Bucky Gel.

Silicon nanowires (NWs) are appealing building blocks for low-cost novel concept devices with improved performances. In this research paper, we realized a hybrid platform combining an array of vertically oriented Si NWs with different types of bucky gels, obtained from carbon nanotubes (CNT) dispersed into an ionic liquid (IL) matrix. Three types of CNT bucky gels were obtained from imidazolium-based ionic liquids (BMIM-I, BIMI-BF4, and BMIM-Tf2N) and semiconductive CNTs, whose structural and optical responses to the hybrid platforms were analyzed and compared. We investigated the electrical response of the IL-CNT/NW hybrid junctions in dark and under illumination for each platform and its correlation to the ionic liquid characteristics and charge mobility. The reported results confirm the attractiveness of such IL-CNT/NW hybrid platforms as novel light-responsive materials for photovoltaic applications. In particular, our best performing cell reported a short-circuit current density of 5.6 mA/cm2 and an open-circuit voltage of 0.53 V.

Human papilloma virus integration sites and genomic signatures in head and neck squamous cell carcinoma.

A prevalence of around 26% of human papillomavirus (HPV) in head and neck squamous cell carcinoma (HNSCC) has been previously reported. HPV induced oncogenesis mainly involving E6 and E7 viral oncoproteins. In some cases, HPV viral DNA has been detected to integrate with the host genome and possibly contributes to carcinogenesis by affecting the gene expression. We retrospectively assessed HPV integration sites and signatures in 80 HPV positive patients with HNSCC, by using a double capture‐HPV method followed by next‐generation Sequencing. We detected HPV16 in 90% of the analyzed cohort and confirmed five previously described mechanistic signatures of HPV integration [episomal (EPI), integrated in a truncated form revealing two HPV‐chromosomal junctions colinear (2J‐COL) or nonlinear (2J‐NL), multiple hybrid junctions clustering in a single chromosomal region (MJ‐CL) or scattered over different chromosomal regions (MJ‐SC) of the human genome]. Our results suggested that HPV remained episomal in 38.8% of the cases or was integrated/mixed in the remaining 61.2% of patients with HNSCC. We showed a lack of association of HPV genomic signatures to tumour and patient characteristics, as well as patient survival. Similar to other HPV associated cancers, low HPV copy number was associated with worse prognosis. We identified 267 HPV‐human junctions scattered on most chromosomes. Remarkably, we observed four recurrent integration regions: PDL1/PDL2/PLGRKT (8.2%), MYC/PVT1 (6.1%), MACROD2 (4.1%) and KLF5/KLF12 regions (4.1%). We detected the overexpression of PDL1 and MYC upon integration by gene expression analysis. In conclusion, we identified recurrent targeting of several cancer genes such as PDL1 and MYC upon HPV integration, suggesting a role of altered gene expression by HPV integration during HNSCC carcinogenesis.

Hybrid Junction Termination Consisting of a Variation Lateral Doping Structure and a Spiral Polysilicon Resistive Field Plate

A hybrid junction termination structure consisting of a variation lateral doping (VLD) region and a spiral polysilicon resistive field plate (PRFP) is proposed in this brief. Surface electric fields of the VLD region are modulated by the PRFP and distribute more uniformly. Compared with the conventional VLD structure with the same size, its measured breakdown voltage increases by 11%. The breakdown voltage still has a positive temperature coefficient. And, the leakage current changes very little from −40 to 150 °C. Besides, it is more immune to the deviation of the VLD dosage. The deviation range of the VLD dosage increase from −20% - +20% to −50% - +60% when the breakdown voltage keeps above 90% of the maximum value. No extra masks or process steps are needed in power devices with a MOS gate structure, because the gate layer can be used to implement the spiral PRFP. At last, the hybrid termination is not detrimental to the switching characteristic of the device.

Upliftment the rectification behavior of PPy-WO3 nanocomposites for photodetector applications

In this study, PPy-WO3 nanocomposites were prepared with various amount of WO3 nanoparticles using in-situ chemical oxidative polymerization. The structure, surface morphology, functional, optical, electrical properties of PPy-WO3 nanocomposites remained categorized by several investigation approaches. The strong diffraction peak at 2θ = 25°, which confirms amorphous nature of PPy. WO3 confirms the major peaks at 2θ = 23.2°, 23.6°, 24.4° related to monoclinic phase. UV–Visible spectra of PPy and WO3 nanoparticles confirms the decreased band gap. The FESEM investigation elucidates the surface morphology of the samples. An endeavor has been made to fabricate the Ag/p-Si/PPy-WO3/Ag hybrid junction diodes using PPy-WO3 nanocomposites by a low-cost effective doctor-blade method also studied with current–voltage analysis in the dark and light circumstances. The mechanism of Ag/p-Si/PPy-WO3/Ag hybrid junction diode performance was explained in detail, current density (J) - voltage (V) technique is used to calculate the diode parameters. The excellent diode behavior is detected for 50 wt% weight percentage of WO3.

Confinement-induced zero-bias peaks in conventional superconductor hybrids

Majorana bound states in topological superconductors have been predicted to appear in the form of zero-bias conductance peaks of height $2e^{2}/h$, which represents one of the most studied signatures so far. Here, we show that quasi zero-energy states, similar to Majorana bound states, can naturally form in any superconducting hybrid junction due to confinement effects, without relation to topology. Remarkably, these topologically trivial quasi zero-energy states produce zero-bias conductance peaks, thus mimicking the most representative Majorana signature. Our results put forward confinement as an alternative mechanism to explain the ubiquitous presence of trivial zero-bias peaks and quasi zero-energy states in superconductor hybrids.

Sorotan Perkembangan Rekabentuk Antena Jalur Mikro Ekadenyut

A monopulse radar system functions to detect targeted objects by using Sum and Difference signals from the reflected signals. The use of parabolic type antennas in conventional radar systems has disadvantages in terms of space, mass, and manufacturing costs. Therefore, microstrip antennas have been proposed because they are flat, lightweight, and cheaper to fabricate. Multiple devices used to produce the important sum and difference signals i.e., hybrid junctions, directional coupler, comparator, and other related methods are studied in this paper. This is due to each of them has their own advantages and limitations. Monopulse microstrip antenna also can be designed in single and multiple layers. Single layer antenna structure is smaller in size and low cost. However, the downside of this structure is having low bandwidth. On the other hand, the multi-layer structure has a higher bandwidth compared to single layer. Nevertheless, at the same time it is thicker in size, difficult to integrate as well as requires more expensive manufacturing costs. It is found that the combination of a single layered antenna structure design and hybrid coupler has the potential to provide better advantages in terms of simplicity, space and cost.

Exciting odd-frequency equal-spin triplet correlations at metal-superconductor interfaces

We predict the occurrence of odd frequency equal-spin-triplet correlations at a normal metal-superconductor junction. This result is significant because equal-spin-triplet correlations are associated with the presence of dissipation-less pure spin current. Inserting a spin-flipper at the interface of a normal metal-superconductor junction excites equal-spin-triplet correlations. The existence of odd frequency equal-spin-triplet correlations in absence of odd frequency mixed spin-triplet correlations is the main take-home message of this work. It tallies well with the measured local magnetization density of states and spin-polarized local density of states at the interface. The importance of spin-flip scattering to the obtained results is manifest when we compare our normal metal-spin flipper-superconductor junction to other hybrid junctions where either only spin mixing or both spin mixing and spin-flip scattering are present.

In-situ generation Bi12O15Cl6/BiOI core-shell photocatalyst with efficient LED light-driven degradation and antibacterial properties: Factors, degradation pathway and mechanism

• New core/shell Bi 12 O 15 Cl 6 /BiOI hybrid junction was prepared by a facile in-situ generation method. • Bi 12 O 15 Cl 6 /BiOI can effectively remove MO, TC and E.coli under LED light. • h + , •O 2 - and •OH are all active substances in photocatalytic reactions and possible degradation pathway of TC was proposed. • Fermi level reached new equilibrium between p-type BiOI and n-type Bi 12 O 15 Cl 6 . • The core-shell structure and n-p junction effectively promote the separation and migration of photogenic carriers. The construction of composite photocatalytic materials with compact heterojunction is of great significance for improving the properties of materials. To achieve this goal, novel core/shell Bi 12 O 15 Cl 6 /BiOI photocatalyst, with n-p junction heterojunction, was prepared by using p-type BiOI nanosheet coating with lamellar n-type Bi 12 O 15 Cl 6 . A series of techniques including XRD, TEM, HRTEM and BET confirmed the structure of Bi 12 O 15 Cl 6 /BiOI. As expected, methyl orange (MO), tetracycline (TC) and E. coli can be effectively removed by the novel photocatalyst under LED light illumination. The optimal sample Bi 12 O 15 Cl 6 /BiOI can degrade 90.3% MO in 90 min, degrade 75.5% TC in 180 min, and completely destroy E. coli in 40 min. Photocurrent and electrochemical impedance analysis (EIS) show that the separation efficiency of photo-excited electron-hole pairs in the composite material is significantly improved. Between n-type Bi 12 O 15 Cl 6 and p-type BiOI semiconductor, a Fermi level movement produced a more negative conduction band position and a more positive valence band position, which is conducive to the production of active species and the photocatalytic redox reaction. Moreover, the effects of catalyst dosage and pollutant concentration on the degradation of MO and TC were systematically investigated. The capture experiment proved that the superoxide anion radicals (•O 2 − ) and holes (h + ) are main active species in photocatalytic reaction. The intermediates were identified by mass spectrometry analysis (MS), and the possible photocatalytic degradation pathway of TC was proposed.

Numerical and Experimental Investigation on the Influence of Tightening in a Hybrid Single Lap Joint

AbstractHybrid mechanical joints are achieved by the simultaneous use of multiple connection mechanisms such as bolting and bonding. This technique allows to obtain advantages in terms of mechanical properties compared to simple joints such as longer fatigue life and operability in critical environmental conditions. Many parameters influence the structural behavior of the hybrid junctions in this perspective numerical simulation can play a decisive role to the cause. Using hybrid joints allows generally to obtain a more homogeneous stress distribution than bolted ones which is why, over the years, such type of joint is widely used in the automotive and naval industries as well as in the avionics, with particular reference to the residual strength in partially damaged components. In the present work, a numerical model representative of tensile tests on single lap joints characterized by adherends of different nature is presented.

Method to Enhance Directional Propagation of Circularly Polarized Antennas by Making Near-Electric Field Phase More Uniform

A new approach to significantly increase the uniformity in aperture phase distribution, through time synchronization in the near-electric field, of circularly polarized (CP) antennas is presented. The method uses the phase of the CP electric field vectors, obtained through full-wave numerical simulations, and does not rely on any approximation such as ray tracing. The near-field data is post-processed to extract the relative phase difference that exists due to the unsynchronized rotations of the electric field vectors in a plane parallel to the antenna aperture. The phase delay is compensated with a thin time-synchronizing metasurface (TSM) that has a 2-D array of time-delay cells. The method is demonstrated with a prototype made of a two-port patch antenna, which is fed through a hybrid junction, and a TSM that is placed at one wavelength spacing above the patch. When TSM is used with patch antenna, its uniform phase area increases manifold thus increasing far-field directivity from 6.8 to 22 dBic.

Effect of chiral anomaly on Andreev reflection in a tilted Weyl semimetal hybrid junction

We study the influence of the chiral anomaly of a time-reversal broken Weyl semimetal on Andreev reflection in a superconductor junction. It is found that the chiral chemical potential can lead to the switching between the retro Andreev reflection (RAR) and specular Andreev reflection (SAR), which appears in both intraband and interband electron-hole conversion, violating the common rule that the intraband conversion is the RAR while the interband one is the SAR. This switching effect is dependent on the tilt of the Weyl cones and the direction of the line connecting the two Weyl points. In addition, a perfect Andreev reflection is found at the incident angle, not perpendicular to the junction interface. We also discuss the zero-bias differential conductance which provides an observable signature of the switching effect, especially for the switching between RAR and SAR caused by band transition. These findings are useful in better understanding the Andreev reflection types and detecting the chiral anomaly.

Z-Piezo Pulse-Modulated STM Break Junction: Toward Single-Molecule Rectifiers with Dissimilar Metal Electrodes.

Fabricating single-molecule junctions with asymmetric metal electrodes is significant for realizing single-molecule diodes, but it remains a big challenge. Herein, we develop a z-piezo pulse-modulated scanning tunneling microscopy break junction (STM-BJ) technique to construct a robust asymmetric junction with different metal electrodes. The asymmetric Ag/BPY-EE/Au single-molecule junctions exhibit a middle conductance value in between those of the two individual symmetric metal electrode junctions, which is consistent with the order of calculated energy-dependent transmission coefficient T(E) of the asymmetric junctions at EF. Furthermore, the single-molecule conductance of Ag/BPY-EE/Au decreases by about 70% when reversing the bias voltage from 100 to -100 mV, and a clear asymmetric I-V feature at the single-molecule level is observed for these junctions. This rectifying behavior could be ascribed to a different interfacial coupling of molecules at the two end electrodes, which is confirmed by the different displacement of T(E) at the two bias voltages. Other asymmetric junctions exhibit similar rectifying behavior. The current work provides a feasible way to fabricate hybrid junctions based on asymmetric metal electrodes and investigate their electron transport toward the design of molecular rectifiers.