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A Novel Multi-Band Electromagnetic Band-Gap Structure

A Novel Multi-Band Electromagnetic Band-Gap Structure

Abstract—In this paper, a novel multi-band EBG structure is presented. By making slots on Sievenpiper High Impedance Surface (HIS) to increase the inductance and capacitance, the resonant frequency of the EBG structure can be significantly reduced. Transmission line method is used to determine the band-gap of the EBG structure. The simulated and experimental results show that the novel EBG structure can provide multiple band-gap. This proposed EBG can be usefully applied to multiple frequency antennas and low profile antennas.

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Resolution of the Band Gap Prediction Problem for Materials Design

Resolution of the Band Gap Prediction Problem for Materials Design

of plane wave basis set codes. Band gap calculations for 70 compounds with ex- perimental band gaps ranging from 0–15 eV were performed using the B3PW91 hybrid density functional in the modified code. Comparison of these calculations to literature GW results shows that the B3PW91 hybrid density functional is more ac- curate than the theoretically rigorous GW (many-body perturbation) method. When used with a Gaussian basis set, hybrid density functional calculations are about 3–4 orders of magnitude faster than GW calculations. Across this wide array of compounds, B3PW91 is accurate enough to enable the prediction of band gaps for materials that have not been synthesized. This accuracy and computational speed make Gaussian basis set B3PW91 an ideal choice for high-throughput materials de- sign applications, and constitutes a solution to the band gap prediction problem for materials design. This constitutes the main result of the thesis.
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Band structure calculations of Si–Ge–Sn
alloys: achieving direct band gap
materials

Band structure calculations of Si–Ge–Sn alloys: achieving direct band gap materials

This system is currently believed to be of great practical interest, since it offers a direct band gap in Ge at a reasonable level of strain (>1.8%) as well as type-I heterostructure [11] (of importance for realisation of quantum well structures), together with a small thermal expansion mismatch between the two materials [6]. This level of strain is considered acceptable for growth of good quality layers, provided they are below the critical thickness [6] (the same limitation applies to strained Ge 1−x Sn x grown on relaxed

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Enhanced Low Profile, Dual-Band Antenna via Novel Electromagnetic Band Gap Structure

Enhanced Low Profile, Dual-Band Antenna via Novel Electromagnetic Band Gap Structure

The literature provides a few methods to analyse EBG structures, specifically how to identify their band gaps [13]. One methodology, based on the dispersion diagram, relies on studying the wave vector in function of frequency. This identification technique is more commonly used when being solved by the FDTD (Finite Deference Time Domain) method. The dispersion diagram can also be calculated using an eigen mode solver to draw a band gap [14]. The reflection phase is also a widely used method that allows the characterization of a unit cell, and from that on, to the identification of the band gap. This method is based on the reflection phase curve extraction, which can then be used to see if the band gap criterion is met between 0 ◦ and 180 ◦ or ± 45 ◦ [15].
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Frequency modulation in Direct Band gap Semiconductors: Band structure and Density of state mass effects

Frequency modulation in Direct Band gap Semiconductors: Band structure and Density of state mass effects

Optical modulators especially the frequency modulators are being extensively used in the fabrication of tunable coherent transmitters and detectors with considerably high efficiency and low loss. The choice of a nonlinear medium and operating frequency are crucial aspects in design and fabrication of frequency modulators. Amongst different types of nonlinear media, direct gap semiconductors offer considerable range of fabrication of optoelectronic devices because of large optical nonlinearities in the vicinity of band gap resonant transitions [2, 3] and they are substantially transparent for the photon energies less than the band gap energies [4]. Devices made of semiconductors may operate both at normal incidence and/or in waveguides and they are integrable with other optoelectronic components. Here it is worth mentioning that resonant and non-resonant optical nonlinearity of semiconductors have been utilized for fabrication of nonlinear optical devices.
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Band Gap Simulations of 1-Dimensional Photonic Crystal

Band Gap Simulations of 1-Dimensional Photonic Crystal

Abstract— one dimensional photonic crystal is the simplest possible type of the photonic crystals. The investigation of photonic structures by mathematical and a simulation method is highly important. At optical frequencies the optical density inside a photonic crystal varies periodically, they have the property to strongly affect the propagation of light waves at these optical frequencies. In the present work, band gap has been computed for a 1D photonic crystal. Both Plane Wave Expansion (PWE) and Finite-Difference-time-Domain (FDTD) methods are widely used for band gap computation of photonic crystals. Due to its advantage over PWE method, we have used FDTD method for computation of band gap for 1D photonic crystal.
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Polyaniline/MnTiO3Nanocomposites: Fabrication, Characterization and Optical band gap

Polyaniline/MnTiO3Nanocomposites: Fabrication, Characterization and Optical band gap

The absorption coefficient and optical band gap of a material are two important parameters bywhich the optical characteristics and its practical applications in various fields are judged.Fig.1. shows the DRS patterns of pure MnTiO 3 and the PANI/MnTiO 3 NCs with 10 and 20wt% of MnTiO 3 NPs loading. In fig.1a. a sharp absorption peak is observed around325nm, which indicates the optical band gap attributed to the O 2- Ti 4+ þcharge-

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Design of New Compact Photonic Band Gap Filter and Their Advantages

Design of New Compact Photonic Band Gap Filter and Their Advantages

The photonic band-gap (PBG) [1] structures are effective in microwave applications that provide an effective control of electromagnetic (EM) waves along specific direction and performance. Photonic band gap structures for microstrip line have been topic of research in recent year. The term PBG is introduced as a structure which influence or even changes the electromagnetic properties of materials. The periodic structure created in materials such as substrate or metals [2]. Recently a Photonic band gap structure consisting of small metal pads with grounding via which used to improve the performance of a patch antenna [1], [2]. The PBG structure provides a certain frequency bands which cannot propagate. PBG structures are most widely used in various applications like microwave filters, antenna and other devices. The different structures LPF, BSF, power divider, power amplifier etc. may be implemented [3]. In addition to DGS (defected ground plane) [4] and EBG (electromagnetic band gap) structure, PBG have been created by etching different shapes in ground plane, which increase the inductance and capacitance values of microstrip line. The above technique used for eliminate undesired output response and sharp stop band for LPF [5], [6].
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Electromagnetic Susceptibility of an Electromagnetic Band-Gap Filter Structure

Electromagnetic Susceptibility of an Electromagnetic Band-Gap Filter Structure

Abstract—In a dual-plane compact electromagnetic band-gap (C- EBG) microstrip structure, patches are etched periodically in the ground plane to prohibit the propagation of electromagnetic waves in certain frequency bands so as to provide filtering functionality. However, the existence of the etched patches in the ground plane becomes a natural concern for the reason that these structures might be more prone to electromagnetic interference from nearby radiating components as compare to a microstrip filter with a perfect ground plane. In this paper, an investigation into the electromagnetic susceptibility of a C-EBG filter structure is presented. This study examines the effects of the interference source on the performance of a C-EBG structure in terms of the relative frequency, power level, position, and polarization. From the study, useful guidelines are drawn for the applications of EBG microstrip structures in an environment rich in electromagnetic interference.
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Electromagnetic band gap (EBG) for microstrip antenna design

Electromagnetic band gap (EBG) for microstrip antenna design

The scopes of work of this project are to study the basic electromagnetic band gap (EBG) properties from several published papers and books, design a conventional rectangular microstrip antenna and the new EBG structure operating at 2.4GHz frequency.

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Low band-gap benzothiadiazole conjugated microporous polymers

Low band-gap benzothiadiazole conjugated microporous polymers

low level of microporosity has reduced going from BCMP-5 to BCMP-5-C (Fig. S4)) or has aggregated in the hyperbranched polymer network, affecting gas diffusion into the pores. In bulk hetero-junction solar cells, solution blending of fullerene derivatives with low band-gap conjugated polymers can effectively quench fluorescence of the conjugated polymers and facilitate charge transfer from electron donor to electron acceptor materials. 29 With this in mind, we investigated the influence of

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Genetic Algorithm Optimized Electromagnetic Band Gap Structure for Wide Band Noise Suppression

Genetic Algorithm Optimized Electromagnetic Band Gap Structure for Wide Band Noise Suppression

In the present paper, a simple EBG structure is proposed that provides a wide band gap of 20 GHz. This structure is generated by placing square metal patches on the substrate. The unit cell dimensions were taken to be less than half the operating wavelength at 2 GHz and 2.5 GHz, at which the structure has been analyzed for signal integrity. The well-known evolutionary algorithm called GA is used to determine the position of the metal patches on the PCB such that the band gap is optimized to the desired value. Generally, 4–5 unit cells are needed to provide good isolation characteristics [15], which increase the physical size of the EBG structure. In this paper, a single cell EBG [12] structure is proposed that offers an isolation of 30 dB for 20 GHz bandwidth and an isolation of 40 dB for 17.4 GHz bandwidth. The structure is also analyzed for its Signal Integrity.
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Triple Band Notched UWB Antenna Design Using Electromagnetic Band Gap Structures

Triple Band Notched UWB Antenna Design Using Electromagnetic Band Gap Structures

Abstract—A circular monopole antenna for ultra wideband (UWB) applications with triple band notches is proposed. The proposed antenna rejects worldwide interoperability for microwave access WiMAX band (3.3 GHz–3.8 GHz), wireless local area network WLAN band (5.15 GHz–5.825 GHz) and X-Band downlink satellite communication band (7.1 GHz–7.9 GHz). The antenna utilises mushroom- type and uniplanar Electromagnetic Band Gap (EBG) structures to achieve band-notched designs. The advantages of band-notched designs using EBG structures such as notch-frequency tuning, triple-notch antenna designs and stable radiation pattern are shown. The effect of variation of EBG structure parameters on which notched frequency depends is also investigated. Fabricated and measured results are in good agreement with simulated ones.
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Bi-induced band gap reduction in epitaxial InSbBi alloys

Bi-induced band gap reduction in epitaxial InSbBi alloys

III-V-bismide alloys have attracted attention due to their interesting band structure, significant Bi-induced band gap reduction, and increase in spin-orbit splitting which make them suitable for optoelectronic devices operating in the near- and mid-infrared regions. 1–4 While III-SbBi alloys have been less extensively researched than III-AsBi alloys, interest in them is increasing, particularly for high power lasers and detectors in the important 2–5 and 8–14 lm ranges. There are only a few recent reports on the growth and properties of GaSbBi and related alloys, targeting the lower wavelength of these ranges. 5–11 Meanwhile, InSbBi was one of the first dilute bismides to be explored. 12–16
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Electronic Structures and Band Gap of Doped Germanium Nanowires (GeNWs)

Electronic Structures and Band Gap of Doped Germanium Nanowires (GeNWs)

Valence band maxima = - 0.230495 eV so the band gap of circular Ge nanowire = 1.86962 eV as shown in figure 3. Similarly for rectangular Ge nanowire the conduction band minima = 2.01078 eV; valence band maxima = - 0.406183 eV; and the band gap of rectangular Ge nanowire = 1.6046 eV as shown in figure 4. Likewise for triangular Ge nanowire the conduction band minima = 2.35002 eV; Valence band maxima = - 0.0392472 eV; and the band gap of triangular Ge nanowire = 2.31077 eV as shown in figure 5.

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Band Gap Narrowing and Widening of ZnO Nanostructures and Doped Materials

Band Gap Narrowing and Widening of ZnO Nanostructures and Doped Materials

influence of the Cu content because CuO has a smaller band gap of between 1.2 and 1.3 eV [25]. It is observed that for all groups of samples, the band gap energy of the nanomaterials is larger than their micron-sized materials. Band gap widening of nanomaterials are attributed to the quantum mechanical effects of the low-dimensional crys- tallites. At these length scales, overlapping energy levels spread out to become more quantized producing band gap widening in the materials. It is also observed that doped materials have the opposite behaviour, that is, exhibiting band gap narrowing with respect to the undoped samples for each temperature. The band gap energies of doped compounds (Zn 0.99 Cu 0.01 O and Zn 0.99 Mn 0.01 O) are smaller
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Bi induced band gap reduction in epitaxial InSbBi alloys

Bi induced band gap reduction in epitaxial InSbBi alloys

III-V-bismide alloys have attracted attention due to their interesting band structure, significant Bi-induced band gap reduction, and increase in spin-orbit splitting which make them suitable for optoelectronic devices operating in the near- and mid-infrared regions. 1–4 While III-SbBi alloys have been less extensively researched than III-AsBi alloys, interest in them is increasing, particularly for high power lasers and detectors in the important 2–5 and 8–14 lm ranges. There are only a few recent reports on the growth and properties of GaSbBi and related alloys, targeting the lower wavelength of these ranges. 5–11 Meanwhile, InSbBi was one of the first dilute bismides to be explored. 12–16
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Growth, characterization, and functionalization of wide band gap oxide alloys

Growth, characterization, and functionalization of wide band gap oxide alloys

Another significant aspect of oxide materials is the possibility of band gap engineering in a multitude of applications which requires for specific band gap en- ergies and/or designing efficient quantum structures with appropriate alignment of the conduction and valence bands of the two different materials in the a hetero- junctions. Such induced quantum effects such as quantum confinement effects and integer/fractional quantum Hall effects can be applied for the enhancement of op- toelectronic performance, for example, in light emitting diodes (LEDs), laser diodes (LDs), solar cells, and heterojunction bipolar transistors [3, 30–32]. In principle, the tunability of the band gap of oxides can be achieved by; (i ) the incorpora- tion of other oxide species into the host as a varied chemical composition, (ii) strain-induced transition in their crystal structures and variations in the density- of-states, effective strain engineering, and (iii ) size-dependent energy confinement on a nanoscale [33–36]. By compositional substitution in the host, the band gap energy, conduction/valence band orbitals, and chemical stability can be modulated to satisfy the criteria with respect to a phase miscibility gap. The conduction and valence bands for different chemical group compound materials are based on the ionization potential and electron affinity of the constituent elements.
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Band gap modulation of graphyne: A density functional theory study

Band gap modulation of graphyne: A density functional theory study

It should be mentioned that the lack of an energy gap is one of the biggest challenges for use of graphene and graphyne in nanoelectronic devices. Because of these requisites, several physical and chemical methods including doping with impurity, applying electric and magnetic fields, chemical functionalization, and organic molecules adsorption, etc. were proposed to open a band gap in graphene [11-31]. As an example, the possibility of modifying the electronic properties of graphene and graphyne was reported by doping with B and N atoms [20, 21]. It was also reported that the electronic properties of graphene was modified and the energy band gap was opened by adsorption of different functional groups such as H, F, OH, COOH, O, acryne and carbene groups [22-26]. In addition, it was found that a single graphene layer, when deposited on substrates such as silicon dioxide or silicon carbide, loses its semimetallic characteristic due to strong chemical interaction with the underlying substrate [13, 15-17]. Moreover, charge transfer doping by organic molecules is a promising way to create a band gap in graphene [18, 19, 27]. As an example, it was shown that surface modification of graphene by organic molecule such as tetracyanoethylene (TCNE) is an effective method to control the electronic structure of graphene [18, 19]. Furthermore, it was found that the Dirac cones in the electronic structures of monolayer graphene are very stable against external stress and electric field [28-30]. While the electric field changes significantly the electronic properties of bilayer graphene [31].
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H-tailored surface conductivity in narrow band gap In(AsN)

H-tailored surface conductivity in narrow band gap In(AsN)

Although the physics of hydrogen in wide-band gap dilute nitrides, such as Ga(AsN), has been researched both experimentally and theoretically, the effects of hydrogen on the electronic properties of narrow band gap III-N-Vs, such as In(AsN), are still largely unknown. 6–8 The mechanisms of hydrogen diffusion, H-N interaction, and, in particular, the passivation of the electronic activity of nitrogen by hydrogen, which is well established for wide bandgap III-N-Vs, 3 can be qualitatively different in narrow band gap compounds and may open perspectives in the exploitation of these materials in mid-infrared optoelectronics. 9 In particular, the narrow band gap InAs semiconductor has an electron accumulation layer in the surface region with a Fermi level, E F , located
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