Band Hybridization Research Articles

Electronic properties and modulation effects on edge-modified GeS<sub>2</sub> nanoribbons

GeS<sub>2</sub> monolayers have been successfully prepared in this work. To further expand their applications and discover new physical properties, we construct armchair-type GeS<sub>2</sub> nanoribbons (AGeS<sub>2</sub>NR) and use different concentrations of H and O atoms for the edge modificationand their structural stabilities, electronic properties, carrier mobilities, and physical field modulation effects are studied in depth. The results show that the edge-modified nanoribbon has a higher energy and thermal stability. The bare edge nanoribbon is a nonmagnetic semiconductor, while the edge modification can change the bandgap of AGeS<sub>2</sub>NR and make it a wide or narrowed bandgap semiconductor, or a metal, which is closely related to the elimination or partial elimination of the edge states or the creation of hybridization bands. Thus edge modification extends the application range of nanoribbons in the fields of electronic devices and optical devices. In addition, the carrier mobility is found to be very sensitive to the edge modification: the carriers’ (electrons’ and holes’) mobilities of nanoribbons can be adjusted to a difference of up to one order of magnitude, and the difference in carrier mobility polarization can be tuned to one order of magnitude. Strain effect studies reveal that the semiconducting nanoribbons are robust in keeping the electronic phase unchanged over a wide strain range, which is useful for maintaining the stability of the electron transport in the related device. Most of the semiconducting nanoribbons have the stability to keep the semiconducting properties unchanged under high external electric field, but the bandgap can be reduced significantly with the increase of the electric field. In short, this study provides a theoretical analysis and reference for understanding the property of GeS<sub>2</sub> nanoribbons and developing related devices.

Experimental Variable Band Hybrid Current Mode Control for High Power High Frequency Inverter in Electro Surgical Applications

Experimental Variable Band Hybrid Current Mode Control for High Power High Frequency Inverter in Electro Surgical Applications

Breggovskie rezonansy v mul'tiferroidnom kristalle s dvoynoy nelineynost'yu

The influence of double (electrical and magnetic) nonlinearity on the Bragg resonances of the hybrid electromagnetic-spin waves in a multiferroic crystal has been theoretically and experimentally revealed. The multiferroic crystal consists of an yttrium iron garnet layer with a periodic system of grooves on the surface and a ferroelectric strontium–barium titanate layer. A dispersion relation for the hybrid waves is obtained, and the mechanism of formation of main and hybrid band gaps, namely, suppression bands, is revealed. It is shown that taking into account the magnetic nonlinearity leads to frequency rearrangement of both band gaps and taking into account the electrical nonlinearity leads to frequency rearrangement of only the hybrid band gap. In the general case, the effects of the electrical and magnetic nonlinearities on the hybrid band gap can be compensated.

Room temperature two-dimensional electron gas scattering time, effective mass, and mobility parameters in AlxGa1−xN/GaN heterostructures (0.07 ≤ x ≤ 0.42)

AlxGa1−xN/GaN high-electron-mobility transistor (HEMT) structures are key components in electronic devices operating at gigahertz or higher frequencies. In order to optimize such HEMT structures, understanding their electronic response at high frequencies and room temperature is required. Here, we present a study of the room temperature free charge carrier properties of the two-dimensional electron gas (2DEG) in HEMT structures with varying Al content in the AlxGa1−xN barrier layers between x=0.07 and x=0.42. We discuss and compare 2DEG sheet density, mobility, effective mass, sheet resistance, and scattering times, which are determined by theoretical calculations, contactless Hall effect, capacitance-voltage, Eddy current, and cavity-enhanced terahertz optical Hall effect (THz-OHE) measurements using a low-field permanent magnet (0.6 T). From our THz-OHE results, we observe that the measured mobility reduction from x=0.13 to x=0.42 is driven by the decrease in 2DEG scattering time, and not the change in effective mass. For x<0.42, the 2DEG effective mass is found to be larger than for electrons in bulk GaN, which in turn, contributes to a decrease in the principally achievable mobility. From our theoretical calculations, we find that values close to 0.3m0 can be explained by the combined effects of conduction band nonparabolicity, polarons, and hybridization of the electron wavefunction through penetration into the barrier layer.

Spin and valley-polarized multiple Fermi surfaces of α -RuCl3/bilayer graphene heterostructure

We report the transport properties of α-RuCl3/bilayer graphene heterostructures, where carrier doping is induced by a work function difference, resulting in distinct electron and hole populations in α-RuCl3 and bilayer graphene, respectively. Through a comprehensive analysis of multi-channel transport signatures, including Hall measurements and quantum oscillation, we unveil significant band modifications within the system. In particular, we observe the emergence of spin and valley-polarized multiple hole-type Fermi pockets, originating from the spin-selective band hybridization between α-RuCl3 and bilayer graphene, breaking the spin degree of freedom. Unlike the α-RuCl3/monolayer graphene system, the presence of different hybridization strengths between α-RuCl3 and the top and bottom graphene layers leads to an asymmetric behavior of the two layers, confirmed by effective mass experiments, resulting in the manifestation of valley-polarized Fermi pockets. These compelling findings establish α-RuCl3 proximitized to bilayer graphene as an outstanding platform for engineering its unique low-energy band structure.

Research on panoramic mosaic of multiple images

With the continuous improvement of the manufacturing process of mobile phone cameras, the demand for panoramic photos by the industry and the public is not limited to ordinary cylindrical panoramic images, so a series of accurate panoramic image stitching technologies have been derived. However, these techniques often fail to take into account the stitching effect and speed, and there is still a technical gap in current multi-image panoramic stitching techniques. This article mainly compares the accuracy and efficiency of various feature extraction algorithms to select the most suitable algorithm for obtaining feature point pairs and estimating the homography matrix. Finally, a dual band hybrid algorithm is used to distort and fuse multiple images into panoramic photos. The results show that the panoramic images generated with multiple images using the algorithm provided in this paper are very good, even though there is a little bit of light and dark interlacing and ghosting.

ZrTe2 Compound Dirac Semimetal Contacts for High-Performance MoS2 Transistors.

Recent investigations reveal elemental semimetal (Bi and Sb) contacts fabricated with conventional deposition processes exhibit a remarkable capacity of approaching the quantum limit in two-dimensional (2D) semiconductor contacts, implying it might be an optimal option to solve the contact issue of 2D semiconductor electronics. Here, we demonstrate novel compound Dirac semimetal ZrTe2 contacts to MoS2 constructed by a nondestructive van der Waals (vdW) transfer process, exhibiting excellent ohmic contact characteristics with a negligible Schottky barrier. The band hybridization between ZrTe2 and MoS2 was verified. The bilayer MoS2 transistor with a 250 nm channel length on a 20 nm thick hexagonal boron nitride (h-BN) exhibits an ION/IOFF current ratio over 105 and an on-state current of 259 μA μm-1. The current results reveal that 2D compound semimetals with vdW contacts can offer a diverse selection of proper semimetals with adjustable work functions for the next-generation 2D-based beyond-silicon electronics.

Microstrip dual band hybrid directional resonator antenna with volume reduction

This paper presents a novel design of a single-layer, horizontally polarized, dual-band, omni- and multi-directional hybrid dielectric resonator antenna (DRA) feeding through a 50 Ω coaxial connector. The proposed antenna consists of an FR4 substrate, a regular ground plane and a cross-shaped patch. The connector is placed at the middle point of the square ground plane. Above the microstrip patch, four similar solid dielectric resonator elements are placed diagonally. These DRA structures generate the TE111, hybrid HEM22δ modes and put up an ideal magnetic dipole and an electric quadrupole far-field radiation pattern. To verify the idea, an optimized antenna model is fabricated and tested. A reasonable agreement between the measured and simulated results is obtained. The measured impedance bandwidths of the TE111 and HEM22δ modes are 4.26 % (2.9–3.2 GHz) and 4.34 % (4.4–4.6 GHz), respectively. The proposed antenna has a stable omnidirectional radiation pattern at the first resonance frequency and a directional radiation pattern at the second resonance frequency and provides volume reduction.

Origin of the magic angle in twisted bilayer graphene from hybridization of valence and conduction bands

Origin of the magic angle in twisted bilayer graphene from hybridization of valence and conduction bands

Suture Tie-down Forces and Cyclic Contractile Forces after Undersized Tricuspid Annuloplasty Using a Tri-Ad Adams Tricuspid Annuloplasty Ring in an Ovine Model.

This study evaluated suture tie-down forces and cyclic contractile forces after undersized tricuspid annuloplasty using a hybrid band. Downsized tricuspid annuloplasty was planned in adult male sheep using eight force transducers attached from the septal to the anterior annular areas of the ring (segments 1 and 2, flexible septal; segments 3 and 4, semi-rigid posterior; segments 5 and 6, semi-rigid anterior; segments 7 and 8, flexible anterior). Cyclic contractile forces were analyzed at three different levels of peak right ventricular pressure: 30, 50, and 70 mmHg. Eight 5-year-old male Corriedale sheep (average body weight = 66.8 kg) were used. The average suture tie-down force was 4.42 (standard deviation: 2.32) N. When the forces were compared, it was lowest in the flexible anterior area and highest in the flexible septal area (p < 0.001). With right ventricular pressure of 30 mmHg, the average cyclic contractile forces was lowest at segment 3 (0.07 [standard deviation: 0.07] N) and highest at segment 7 (0.15 [standard deviation: 0.08] N). The cyclic contractile forces were 0.12 (standard deviation: 0.1) N, 0.09 (standard deviation: 0.12) N, 0.14 (standard deviation: 0.1) N, and 0.13 (standard deviation: 0.09) N in the flexible septal, semi-rigid posterior, semi-rigid anterior, and flexible anterior parts, respectively (p = 0.208). As the peak right ventricular pressure increased to 50 and 70 mmHg, the cyclic contractile forces of each area increased significantly (p < 0.001). Despite this increase, the cyclic contractile forces remained low (0.1 and 0.3 N), and differences in cyclic contractile forces between segments and between annular areas showed similar patterns. The flexible end of the hybrid band reduces the cyclic contractile forces and might prevent annular tears after ring tricuspid annuloplasty, and the risk of tear would be low even in the septal area.

Electronic structure of Sb ultrathin film on Bi(111) with large lattice mismatch

Topological phase transitions have been actively investigated to understand the fundamental properties and to develop applications for spintronics. In this study, we focused on Sb ultrathin films that undergo a topological phase transition by lattice strain. In order to fabricate samples with a lattice constant theoretically predicted to be topologically nontrivial, Sb ultrathin films are prepared on a Bi substrate. The surface structure and electronic states of the Sb/Bi heterostructure were confirmed by the low-energy electron diffraction measurement and angle-resolved photoemission spectroscopy. For 2 and 3 BL Sb films, we demonstrated the possibility of creating well-ordered immiscible ultrathin films of Sb on a Bi substrate and observed a “V”-shaped electronic band, which is significantly different from the electronic state of Bi thin films and freestanding Sb ultrathin films. This suggests that the electronic state of the Sb ultrathin film is affected by the Bi substrate. We propose that the “V”-shaped band originates from a topological phase transition due to expanded lattice constants and band hybridization between Bi and Sb. This heterostructure will provide a new platform for investigating the topological phase transitions and applications.

Pseudogap formation due to charge-transfer transition and Kondo effect

We investigate the doping evolution of the electronic state of the three-band t-J-U model considering the normal state of the hole-doped high- superconducting cuprate. In our model, when some number of holes are doped into the undoped state, the d electron exhibits the charge-transfer (CT)-type Mott-Hubbard transition along with a chemical potential jump. A reduced CT gap is formed from the p band and the coherent component of the d band, and it shrinks due to charge fluctuations as more holes are doped as in the pseudogap (PG) phenomenon. This trend is reinforced as the d-p band hybridization is increased, and a Fermi liquid state is retrieved as in the Kondo effect. These suggest that the PG in the hole-doped cuprate emerges due to the CT transition and the Kondo effect.

Approaching the quantum limit in two-dimensional semiconductor contacts.

The development of next-generation electronics requires scaling of channel material thickness down to the two-dimensional limit while maintaining ultralow contact resistance1,2. Transition-metal dichalcogenides can sustain transistor scaling to the end of roadmap, but despite a myriad of efforts, the device performance remains contact-limited3-12. In particular, the contact resistance has not surpassed that of covalently bonded metal-semiconductor junctions owing to the intrinsic van der Waals gap, and the best contact technologies are facing stability issues3,7. Here we push the electrical contact of monolayer molybdenum disulfide close to the quantum limit by hybridization of energy bands with semi-metallic antimony ([Formula: see text]) through strong van der Waals interactions. The contacts exhibit a low contact resistance of 42 ohm micrometres and excellent stability at 125 degrees Celsius. Owing to improved contacts, short-channel molybdenum disulfide transistors show current saturation under one-volt drain bias with an on-state current of 1.23 milliamperes per micrometre, an on/off ratio over 108 and an intrinsic delay of 74 femtoseconds. These performances outperformed equivalent silicon complementary metal-oxide-semiconductor technologies and satisfied the 2028 roadmap target. We further fabricate large-area device arrays and demonstrate lowvariability in contact resistance, threshold voltage, subthreshold swing, on/off ratio, on-state current and transconductance13. The excellent electrical performance, stability and variability make antimony ([Formula: see text]) a promising contact technology for transition-metal-dichalcogenide-based electronics beyond silicon.

Band gap opening in graphene by hybridization with Au (001) reconstructed surfaces

Au(001) surfaces exhibit a complex reconstructed structure $[\mathrm{Hex}\ensuremath{-}\mathrm{Au}(001)]$ comprising a hexagonal surface and square bulk lattices, yielding a quasi-one-dimensional corrugated surface. When graphene was grown on this surface, the periodicity of the corrugated surface was predicted to change the electronic structure of graphene, forming bandgaps and new Dirac points. Furthermore, the graphene--Au interface is promising for bandgap generation and spin injection due to band hybridization. Here, we report the angle-resolved photoemission spectroscopy and density functional calculation of graphene on a $\mathrm{Hex}\ensuremath{-}\mathrm{Au}(001)$ surface. The crossing point of the original and replica graphene \ensuremath{\pi} bands showed no bandgap, suggesting that the one-dimensional potential was too small to modify the electronic structure. A bandgap of 0.2 eV was observed at the crossing point of the graphene \ensuremath{\pi} and Au $6sp$ bands, indicating that the bandgap is generated using hybridization of the graphene \ensuremath{\pi} and Au $6sp$ bands. We discussed the hybridization mechanism and concluded that the R30 configuration between graphene and Au and an isolated electronic structure of Au are essential for effective hybridization between graphene and Au. We anticipate that hybridization between graphene \ensuremath{\pi} and Au $6sp$ would result in spin injection into graphene.

Adaptive Hybrid Bivariate Double Density Discrete and Complex Wavelet for Image Denoising

Image denoising is an important step in eliminating any noise impact in any image transmission process. Recently we presented two approaches for Bivariate based image denoising. They were Double Density Discrete Wavelet Transform (DD DWT) and Double Density Dual Tree Complex Wavelet Transform (DD CWT). In both techniques we decomposed noisy images with either DD DWT or DD CWT decompositions and then applied the Bivariate based denoising technique for noise removal. In this paper we propose an adaptive hybrid technique for Bivariate based image denoising that is based on the synthesis of DD-DWT bands or DD-CWT bands but with different weights, to deliver enhanced image features with less denoising impact especially around image edges, which is the most effected by noisy transmission channels. This proposed technique has been also enhanced by edge sharpening and Eigen analysis, as two separate stages. Simulation result comparisons have been performed between the proposed hybrid band adaptive DD-DWT and DD-CWT technique and the two primary techniques DD-DWT, DD- CWT, as well as other superior literature techniques such the original bivariate denoising technique with both original Complex Wavelet Transform and Double Density decompositions. This work in specific compares between Double Density DWT and Double Density CWT decompositions, proposes new filter design that suits each of them and proposes a hybrid technique between as will be shown.

High-temperature stabilized defect pyrochlore Bi2−xFexWO6 nanostructures and their effects on photocatalytic water remediation and photo-electrochemical oxygen evolution kinetics

Optimal Fe-substituted Bi2WO6 nanostructures, stabilized at higher temperatures, exhibited better band hybridization leading to improved photocatalytic and photoelectrochemical performance.

Active Noise Control Scheme for Smart Beds Based on a Wide and Narrow Band Hybrid Control Algorithm

Active Noise Control Scheme for Smart Beds Based on a Wide and Narrow Band Hybrid Control Algorithm

Dual objective bandit for best channel selection in hybrid band wireless systems

Dual objective bandit for best channel selection in hybrid band wireless systems

Design and Analysis of an O+E-Band Hybrid Optical Amplifier for CWDM Systems.

Broadband amplification in the O+E-band is very desirable nowadays as a way of coping with increasing bandwidth demands. The main issue with doped fiber amplifiers working in this band such as the bismuth-doped fiber amplifier is that they are costly and not widely available. Therefore, a wideband and flat-gain hybrid optical amplifier (HOA) covering the O+E-band based on a parallel combination of a praseodymium-doped fiber amplifier (PDFA) and a semiconductor optical amplifier (SOA) is proposed and demonstrated through numerical simulations. The praseodymium-doped fiber (PDF) core is pumped using a laser diode with a power of 500 mW that is centered at a wavelength of 1030 nm. The SOA is driven by an injection current of 60 mA. The performance of the HOA is analyzed by the optimization of various parameters such as the PDF length, Pr3+ concentration, pump wavelength, and injection current. A flat average gain of 24 dB with a flatness of 1 dB and an output power of 9.6 dBm is observed over a wavelength range of 1270-1450 nm. The noise figure (NF) varies from a minimum of 4 dB to a maximum of 5.9 dB for a signal power of 0 dBm. A gain reduction of around 4 dB is observed for an O-band signal at a wavelength of 1290 nm by considering the up-conversion effect. The transmission performance of the designed HOA as a pre-amplifier is evaluated based on the bit-error rate (BER) analysis for a coarse wavelength-division multiplexing (CWDM) system of eight on-off keying (OOK)-modulated channels, each having a data rate of 10 Gbps. An error-free transmission over 60 km of standard single-mode fiber (SMF) is achieved for different data rates of 5 Gbps, 7.5 Gbps, and 10 Gbps.

Hybridization and localized flat band in the WSe2/MoSe2 heterobilayer

Nearly localized moiré flat bands in momentum space, arising at particular twist angles, are the key to achieve correlated effects in transition-metal dichalcogenides. Here, we use angle-resolved photoemission spectroscopy (ARPES) to visualize the presence of a flat band near the Fermi level of van der Waals WSe2/MoSe2 heterobilayer grown by molecular beam epitaxy. This flat band is localized near the Fermi level and has a width of several hundred meVs. By combining ARPES measurements with density functional theory calculations, we confirm the coexistence of different domains, namely the reference 2H stacking without layer misorientation and regions with arbitrary twist angles. For the 2H-stacked heterobilayer, our ARPES results show strong interlayer hybridization effects, further confirmed by complementary micro- Raman spectroscopy measurements. The spin-splitting of the valence band at K is determined to be 470 meV. The valence band maximum (VBM) position of the heterobilayer is located at the Γ point. The energy difference between the VBM at Γ and the K point is of −60 meV, which is a stark difference compared to individual single monolayer WSe2 and monolayer WSe2, showing both a VBM at K.