Terms Of Transmission Spectrum Research Articles

Performance metrics of doped graphene nanoribbons based nanoscale interconnects: DFT and NEGF analysis

Due to the scaling of devices, the interconnects delay is the most important concern of the current technology, becomes more significant than the IC delay, and leads to overall impact on the performance of the chip. In the present work, doped Zigzag Graphene Nano ribbons (GNR) have been analyzed for the possible nanoscale interconnect applications. The investigation has been performed using the density-functional theory-based ab-initio approach, discussed in terms of structural stability of ribbons, their electronic and transport properties, and the dynamical parameters. Zigzag GNR has been decorated with itssix possible sites along the width, through P and N type impurities, to select the most favorable site for the further analysis. The stability of the systems has been analyzed in terms of formation energy, the electronic properties in terms of band structure and density of states profiles, whereas, the transport properties in terms of transmission spectrum and I–V characteristics. The magnetic inductance, kinetic inductance, electrostatic capacitance, and quantum capacitance have also been calculated as interconnect parameters. The formation energy calculations suggest that the doping at the edge sites of NRs are more favorable. Further, it has been observed that the metallicity of the doped ZGNR enhances with doping, whereas, the I–V characteristics confirms that the N doped ZGNRs have linear current with constant slope. The performance metrics of ZGNRs have also been analyzed using HSPICE, discussed in terms of delay and power delay product, shows that the N doped ZGNRs have lower delay than the other considered counterparts, defends its application as interconnects in the electronic industry.

A highly sensitive refractive index based etched optical fiber sensor for detection of human sperm

Human sperm functionality is one of the important factors for continuing natural reproduction, but due to the variation in environmental factors, its infertility is increased. Such agitating characteristics need the use of sophisticated computer-aided devices, whose precision is not up to the mark, especially for the samples with a low concentration of sperms. Therefore, for the first time, a gold-graphene oxide capped etched optical fiber sensor is presented in this paper for the refractive index (RI) based detection of human sperm samples. The sensor takes the advantage of evanescent waves, which are excreting from the etched region, to sense the analytes. In this work, the sensing analysis is done by considering two different sensor structures, such as core-gold-sperm and core-gold-graphene oxide-sperm. The wavelength compatibility of sensor structures is examined by performing the sensing at 520 nm and 633 nm wavelengths. For the sensing process, the sperm samples of ten different people are collected with their concentration and mobility, and their RIs are obtained by using the ATAGO refractometer. The results are evaluated in terms of transmission spectra, sensitivity, quality factor, and figure of merit (FOM). The obtained results demonstrate that the core-gold-graphene oxide-sperm sensor structure is very efficient at the wavelength of 633 nm with the sensitivity, quality factor, and FOM of 203.72°/RIU, 27.055 RIU−1 and 27.309, respectively.

EFFECT OF UV-IRRADIATION TIME ON THE STRUCTURAL AND OPTICAL PROPERTIES OF POLYCRYSTALLINE OF 720 NM OF ZnSe FILM FOR OPTOELECTRONIC APPLICATIONS

Polycrystalline ZnSe thin films with thickness 720 nm were prepared by thermal evaporation under ultra vacuum onto glass substrates. The optical properties of the as deposited and UV-irradiated films with different exposure times (0, 30, 60, 90, and 120 min.) were reported. The polycrystalline nature of the films was detected by XRD measurements. XRD patterns for UV irradiated films show that the intensities of the peaks increase with increasing the UV-irradiated time but the full width at half maximum (FWHM) decreases. The optical constants of the films were calculated by Swanepoel's method in terms of wedge shape model to obtain both thickness and refractive index with high precision. The energy gap of ZnSe films was determined by using the transmission in terms of transmission spectra in the strong absorption region. In terms of the obtained results, the increase of exposure time improved shrinkage of non-uniform transmission in both the strong and medium absorption region of ZnSe film. The optimal improvement was at UV-irradiation time equal 120 min. Accordingly, the possibility of asserting that such tenability in the optical refractive index and energy gap of ZnSe thin films with UVirradiation serves as a promising film in optoelectronic devices.

Diameter Dependent Electronic, Optical and Transport Properties of CdSe Nanowire: Ab-Initio Study

We report the Density functional theory (DFT) based investigations of diameter dependent electronic and optical properties of CdSe nanowire (CdSe-NW) in its wurtzite phase. The DFT calculations are based on generalized gradient approximation, Perdew Burke and Ernzerhof (PBE) type parameterization and localized double-$$\zeta $$ polarized (DZP) orbital basis set. The cohesive energy, electronic band structure, Young’s modulus and effective mass have been calculated for different diameter 5.56, 14.00, and 22.60 A CdSe nanowires. Larger diameter shows bandgap lowering and higher zero bias conductance in comparison to its small diameter counterparts. Interfrontier orbital analysis for diametrically large nanowire reveals dispersion of canonical orbital across the cross-section of nanowire, hence supporting high charge carrier mobility. Computation of dielectric function for the Optical properties analysis, confirms the broad band absorption and low reflectivity of these nanowires in photonic field. Transport properties of CdSe nanowire have been analysed in terms of transmission spectra and current-voltage characteristic.

Electrical conductivity of dithiophene-based diblock molecular junctions

Electron transport through a diblock molecule containing dithiophene moiety (Diheterocyclopentadiene Dithiophene Dithiol, DXDTDT) has been studied using non-equilibrium Green’s function approach combined with density functional theory. I-V characteristics of five molecular junctions were calculated. The results obtained show a modest current rectification of RR=1.7–3.4 with the highest rectification ratio (RR=3.4) was recorded for DBDTDT at 0.3V. A little negative differential resistance (NDR) behavior was reported for Diborole Dithiophene Dithiol (DBDTDT), Disilole Dithiophene Dithiol (DSiDTDT), and Diarisole Dithiophene Dithiol (DADTDT), with a peak-valley ratio (PVR) range from 1.00 to 1.21. Our findings have been interpreted in terms of transmission spectra and molecular projected self-consistent Hamiltonian.

Effect of gold electrode crystallographic orientations on charge transport through aromatic molecular junctions

ABSTRACTWe examined the electrical conduction through single-molecular junctions comprising of anthracenedithiol molecule coupled to two gold electrodes having ⟨1,0,1⟩, ⟨1,1,0⟩ and ⟨1,1,1⟩ crystallographic orientations. Owing to this jellium model, we evaluated the values of current and conductance using non-equilibrium Green's functions combined with extended Huckel theory. This data was further interpreted in terms of transmission spectra, density of states and their molecular orbital analysis for zero bias. We evinced the oscillating conductance in all three cases, due to the oscillation of orbital energy relative to Fermi level. Our detailed analysis suggested that electrode orientation can tune the molecule–electrode coupling and hence conduction. Anthracene molecular junction with ⟨1,1,0⟩ orientation displayed favourable conduction, when compared to the other two orientations, thus can provide us an insight while designing futuristic molecular electronic devices.

First-Principles Calculations of Electron Transport through Azulene

Electron transport through azulene, a nonalternant hydrocarbon, has been investigated using nonequilibrium Green’s function approach combined with density functional theory. I–V characteristics of azulene wired from different positions between two gold electrodes have been calculated. The results indicated that current strength correlates with orbitals amplitudes. Out of nine investigated azulene dithiolates, four molecular junctions (1,3-, 1,5-, 2,6-, and 4,7-connections) show high current compared with only one position from naphthalene dithiolate (1,4-). A current rectification ratio of ca. 4 was found in case of 2,7-azulene dithiolate. The remaining connections give low to moderate current. Aromaticity and ability of different connections to form quinonoid structure were used to explain electrical conductivity of the studied molecular junctions. The data were interpreted in terms of transmission spectra and molecular projected self-Hamiltonian eigenstates. Orbital symmetry rule and quantum interference have also been discussed.

Electronic Transport Properties of Transition-Metal Terminated Trigonal Graphene Nanoribbons

With the non-equilibrium Green’s function method and density functional theory, we have studied the electronic properties of trigonal graphene nanoribbons, with Fe terminal and H terminal, coupled to gold electrodes. Rectification behavior can be observed when the electrode-molecule contact distance is larger than 2.2 &Aring. The electronic transport is greatly improved in case of Fe terminal which is analyzed in terms of transmission spectra and density of states.

First-principles studies on transport property and adsorption characteristics of trimethylamine on α-MoO3 molecular device

The electronic transport properties and trimethylamine adsorption (TMA) characteristics on MoO3 molecular device are explored using density functional theory (DFT) method via GGA/PBE exchange correlation functional. The density of states spectrum visualizes the localization of charges in MoO3 molecular device upon adsorption of TMA. The transport properties of MoO3 molecular device with adsorption of TMA are studied in terms of transmission spectrum. I–V characteristics of MoO3 molecular device reveal the change in the current upon adsorption of TMA. The present work gives an understanding on MoO3 molecular device, which can be used as an efficient TMA sensor.

Influence of Oxygen, Tellurium, and Zinc Substitution on CdSe Nanoribbon: A First-Principles Investigation

The electronic transport property and band structure of pure cadmium selenide, oxygen, tellurium, and zinc substituted CdSe nanoribbon and defect structured CdSe nanoribbon are studied using density functional theory. The band structure of pure, oxygen, tellurium, and zinc substituted CdSe nanoribbon and defect structured nanoribbon shows a metallic behavior. The localization of charges in the valence band and conduction band is analyzed by the density of states spectrum. The electronic transport properties of CdSe nanoribbon are investigated in terms of transmission spectrum. The transmission can be modified with the substitution impurities such as oxygen, tellurium and zinc in the nanostructure.

BER evaluation of a low-crosstalk silicon integrated multi-microring network-on-chip.

The operation of an integrated silicon-photonics multi-microring network-on-chip (NoC) is experimentally demonstrated in terms of transmission spectra and bit error rates at 10 Gb/s. The integrated NoC consists of 8 thermally tuned microrings coupled to a central ring. The switching functionalities are tested with concurrent transmissions at both the same and different wavelengths. Experimental results validate the analytical model based on the transfer matrix method. BER measurements show performance up to 10(-9) at 10 Gb/s with limited crosstalk and penalty (below 0.5 dB) induced by an interfering transmission.

A detailed microscopic study of the heat transfer at a water gold interface coated with a polymer

We investigate in detail the mechanisms of heat relaxation at a gold:water interface and address the effect of a polymer (DHLA-Jeffamine) coated at the surface. We demonstrate that above a low surface density limit, the adjunction of polymers significantly enhances the interface conductance from the metal to the fluid. From molecular dynamics simulations, we have computed the corresponding increase of thermal conductance. The physical origin of this effect is analyzed in terms of transmission spectra. Transient non-equilibrium simulations finally compare the profile of the thermal field generated with and without the polymer.

Band structure and transport studies on impurity substituted InSe nanosheet – A first-principles investigation

The band structure and electronic transport properties of InSe nanosheet with substitution impurity are studied using density functional theory. The nanostructures of InSe nanosheet exhibit metallic nature. The effect of substitution due to sulfur, tellurium and gallium influences the band structure. The density of states spectrum envisions the density of charges across the InSe nanosheet. The peak amplitudes are observed near the Fermi level and along the valence band in InSe nanosheet. The electron density provides the visualization of density of electrons across InSe nanosheet. The electron density is found to be more on selenium sites than on indium sites. The electronic transport property of InSe nanosheet molecular device is discussed in terms of transmission spectrum, an increase in transmission is observed on moving toward Fermi level along the valence band. The transmission pathways provide the visualization of transmission of electrons along InSe nanosheet. The results of the present work provide insight to tune the band structure of InSe nanosheet with substitution impurity and enhance the electronic transport property of InSe nanosheet.

First-principles insights on tuning band structure and transport property of GaN nanotube

The band structure and transport properties of GaN nanotube are explored using density functional theory with substitution impurity and defect in GaN nanostructure. The band structure varies with oxygen substitution and defect in the GaN nanotube. The density of states spectrum provides the insight for the localization of charges in different energy intervals. The electron density is found to be more in nitrogen site than in gallium site across GaN nanotube. The substitution impurity has the influence over electron density along GaN nanotube. The transport properties are discussed in terms of transmission spectrum. The orbital delocalization gives rise to peak maximum in different energy intervals. The substitution effect of oxygen and defect in the structure has much impact in the transmission along the valence band and conduction band. The finding of present work gives the insight to tailor the band structure and enhance the transport property of GaN nanotube with substitution impurity and defect structure.

FIRST-PRINCIPLES INVESTIGATION ON BAND STRUCTURE AND ELECTRONIC TRANSPORT PROPERTY OF GALLIUM NITRIDE NANORIBBON

The electronic transport property and band structure of pure gallium nitride, oxygen, fluorine, indium substituted gallium nitride nanoribbon and defect structured GaN nanoribbons are investigated by employing first-principles studies using density functional theory. The band structure of pure GaN and indium substituted GaN nanoribbon shows a semiconducting nature. The oxygen, fluorine substituted GaN and defect structured GaN results in metallic behavior. The density of states provides the insight for the localization of charges in the valence band and conduction band. The substitution of oxygen and fluorine enhance the density of charges in valence band and conduction band. The substitution of indium shows an increase in the peak amplitude in density of states. The presence of defect also increases the density of states. The transport properties are studied in terms of transmission spectrum; pure GaN and indium substituted shows a same trend in transmission. In contrast, the transmission can be enhanced by the substitution of oxygen, fluorine and defect in nanoribbon. The information provided in the present study will pave its way to tailor a new material of GaN nanostructures with improved performance in the optoelectronic devices.

Investigation on band structure and electronic transport properties of indium nitride nanoribbon – A first-principles study

The band structure and electronic transport property of indium nitride nanoribbon are investigated by employing first-principles calculation using density functional theory. The nanoribbon of pure InN, oxygen, fluorine and gallium substituted InN nanoribbon and defect InN nanoribbon are studied and analyzed. The band structure of pure InN, oxygen, fluorine and gallium substituted InN shows semiconducting nature whereas defect InN nanoribbon shows a metallic nature. The density of states of InN nanoribbon provides insight for the localization of charges in valence and conduction bands. The transport property are studied in terms of transmission spectrum, pure and gallium substituted InN has almost same transmission, in contrast oxygen and fluorine substituted InN shows a different fashion in transmission spectrum. The presence of defect modifies the transmission that depends on the geometry of the structure and position of the defect in the nanostructure. The information provided in the present study will enhance the electronic transport property to tailor new material with improved performance in optoelectronic devices.

The generalized k-moment method for the modeling of cumulative k-distributions of H2O at high temperature

In the present work, a new formulation, limited to a few number of parameters, of cumulative k-distributions over narrow bands from high resolution spectra is presented. The method is described and assessed through comparisons with reference Line-By-Line (LBL) data for pure H2O, in terms of transmission spectra and cumulative k-distributions. Results demonstrate that the proposed approach is very accurate and therefore is likely to provide reliable approximate models for the cumulative k-distribution and the narrow band transmission functions in uniform media.

Electric resistance of carbon nanotube with a Cu chain: A first-principle calculation

The electric resistance and transport properties of a carbon nanotube (5,5) adsorbed with a copper chain connected with two copper electrodes have been calculated by employing nonequilibrium Green’s functions and Density Functional Theory. The properties of the pure carbon nanotube (5,5) with the Cu junction electrodes have also been calculated as a reference. Both the equilibrium and nonequilibrium conditions have been investigated. The results show that the resistance of the metallic carbon nanotube (5,5) has been reduced by the adsorption of a Cu chain due to the interaction between the Cu and the carbon nanotube. The change of the current–voltage curve slope is also explained in terms of transmission spectrum.

ANATOMIZING ELECTRONIC TRANSPORT THROUGH SATURATED ALKANE MOLECULE WITH DISPARATE TERMINAL ELEMENTS

In this paper, we anatomized transport properties of butane belonging to the saturated alkane group ( C n H 2n+2) using three terminal anchor elements (nitrogen, oxygen and sulfur) in Trans configuration connected to gold electrodes, forming a two probe model. The transport properties of three variants of butane were investigated in terms of Transmission spectra, Eigenstates, I-V characteristics and differential conductance for different values of biasing voltage using Keldysh's non-equilibrium Green's function combined with semi-empirical extended Hückel theory. Amongst the three binding elements, Butane exhibited maximum charge transfer with sulfur, then with nitrogen and least with oxygen. The HOMO-LUMO gap for both nitrogen and Oxygen as terminal anchoring elements suggested that conduction was virtually impossible through Butane in particular cases. Nature of Ballistic current for butane anchored with sulfur is ideal for its applicability as nano-diode or resonant tunneling diodes (RTDs) in arena of quantum-electronics due to its strong coupling between the terminal atoms and carbon atoms of butane. The retrenching order obtained in terms of conductance is S > N > O anchored butane molecule which seemed in full confirmation with the results of Transmission spectrum and its Eigenstates and proved sulfur to be a promising binding element and can produce much better results in comparison to oxygen and nitrogen. This paper marked another step in the field of molecular electronics as the butane anchored with sulfur has characteristics in conjunction to the semiconductor junction diode.

Electronic transport properties in benzene-based heterostructure: Effects of anchoring groups

Using density functional theory (DFT) combined with nonequilibrium Greenʼs functions (NEGF), the electronic transport properties of benzene-based heterostructure molecular devices have been investigated. We focus on the contact geometry between molecules and electrodes, and several different anchoring groups have been considered. The current–voltage characteristics were calculated for positive and negative bias voltages, and discussed in terms of transmission spectra, transferred charges, and molecular projected self-consistent Hamiltonian (MPSH) states. Our results show that the anchoring groups play a crucial role in determining the overall conductivity of the molecular devices. Negative differential resistance (NDR) and rectifying effect can be observed.