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Differential conductance of submicron HEMT is analytically investigated as a function of drain bias for different structural parameters and parasitic effects. Simulation is carried out for two different substrate based devices, Si and... more
Differential conductance of submicron HEMT is analytically investigated as a function of drain bias for different structural parameters and parasitic effects. Simulation is carried out for two different substrate based devices, Si and sapphire, and comparative study is carried out for those structural parameters at which VGS provides maximum transconductance. Poisson's equation and carrier density equations are simultaneously solved to get drain current variations and parasitic effects are invoked through boundary conditions for realistic results. Result speaks that effect of threshold voltage is negligible on sapphire based device over a wider range of horizontal bias. Nanometric channel length provides almost constant conductance profile with insignificant magnitude.
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Based on the climatic conditions like temperature and humidity of the soil, a novel robot is designed which can assist farmers for judging the requirement of water and fertilizer. An efficient algorithm is made for this purpose, which... more
Based on the climatic conditions like temperature and humidity of the soil, a novel robot is designed which can assist farmers for judging the requirement of water and fertilizer. An efficient algorithm is made for this purpose, which sets the threshold level for decision making purpose for different requisites; and also plot the real-time data based on the pre-defined optimum level. Owing to its movement capability, it is able to provide the water and fertilizer at the specific places till the reference level is reached, and then moves thereafter. It also uses remote sensing for determining insect stress and applies insecticides as per requirement. In our agricultural-dominated country, the present solution is a much-needed solution for harvesting problems.
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Lowest two quantum states of a double-well-triple-barrier structure are numerically analyzed for Pöschl-Teller potential profile. Kane-type band nonparabolicity of first order is considered for rational replication purpose, and effective... more
Lowest two quantum states of a double-well-triple-barrier structure are numerically analyzed for Pöschl-Teller potential profile. Kane-type band nonparabolicity of first order is considered for rational replication purpose, and effective mass mismatch between well and barrier layers are included in the computation following the BenDaniel Duke boundary conditions. Transmission coefficient is plotted as a function of input energy flux, and peaks are identified for eigenstate determination in presence and absence of external electric field. Results are compared with that obtained for ideal rectangular geometry, and better quasi-peak characteristics speaks in favor of the proposed structure for photodetector application, where tailoring of subband energy can be achieved by means of structural parameter variations.
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Ripple factor of ternary photonic bandpass filter is analytically computed around 1.55 μm under normal incidence of electromagnetic wave. Parallel nanorod is considered as the metamaterial for the simulation purpose with air gap, and... more
Ripple factor of ternary photonic bandpass filter is analytically computed around 1.55 μm under normal incidence of electromagnetic wave. Parallel nanorod is considered as the metamaterial for the simulation purpose with air gap, and transfer matrix technique is adopted for the investigation. Improved noise rejection characteristics are obtained compared to the published results for positive index materials. Different structural parameters are varied to observe the bandwidth as well as noise variation for optimized performance. The structure is taken as defected one, where the density of point defect is within the limit of fabrication, so that the simulated findings can be taken as realistic.
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A novel package is proposed using JAVA-GUI platform for analyzing filter performance with one-dimensional photonic crystal. With this package, user can provide the required structural parameters (within fabrication limit) for maximum 11... more
A novel package is proposed using JAVA-GUI platform for analyzing filter performance with one-dimensional photonic crystal. With this package, user can provide the required structural parameters (within fabrication limit) for maximum 11 layers 1D structure; and bandpass characteristics can be obtained for both the polarized input conditions. Results are provided for SiO2-air composition, and can be obtained for other material systems with positive refractive indices. Package is useful prior to fabrication for optimizing filter performance.
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Lower return loss and isolation loss of 1-bit RF MEMS switch is analytically investigated for different dielectric materials over the L band to K band. Both unactuated as well as actuated conditions are taken care for simulation purpose,... more
Lower return loss and isolation loss of 1-bit RF MEMS switch is analytically investigated for different dielectric materials over the L band to K band. Both unactuated as well as actuated conditions are taken care for simulation purpose, where overlap area is kept constant. Simulated findings reveal that both the losses are significantly reduced for lower dielectric constant material (SiO2) compared to higher permittivity (Si3N4) upto 30% which is an indirect estimation for measuring upstate and down-state capacitances. Results are also compared with existing data from published literature which speaks in favor of the present work for phase-shifter design.
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In this paper, an efficient synthesis technique for high-speed multivalued ALU for \((2^{p} \pm q)\) radix system is proposed with reduced complexity. Addition, subtraction, increment/decrement and basic logical operations are implemented... more
In this paper, an efficient synthesis technique for high-speed multivalued ALU for \((2^{p} \pm q)\) radix system is proposed with reduced complexity. Addition, subtraction, increment/decrement and basic logical operations are implemented just by rotation of the matrix or shifting of a few elements, and thus minimum number of computational steps is involved; which saves CPU time usage. Matrix representation for all the operations is provided in a tabular manner with pseudocode for the proposed \((2^{p} \pm q)\) radix system in order to understand the detailed procedure of operations. All the pseudocodes have been verified using Xilinx ISE 14.1 simulator using Vertex-7 XC7VX330t device. Lower computation time and complexity make the ALU efficient than those already proposed in the available literature.
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Quantum-confined states of electrons inside quantum ring-like structure have been analytically investigated subjected to crossed electromagnetic field in order to study the effect of field quantization. Schrodinger equation without... more
Quantum-confined states of electrons inside quantum ring-like structure have been analytically investigated subjected to crossed electromagnetic field in order to study the effect of field quantization. Schrodinger equation without considering time-dependency factor is solved with boundary conditions based on the cylindrical geometry of the structure, and lowest two orders Bessel functions are considered for the evaluation of electron energy states. Result reveals that while perpendicular electric field lowers the energy subbands, parallel magnetic field makes the opposite effect; thus creating an interesting trade-off situation. The result is weighted against with that acquired independently in absence of electric field and magnetic field respectively for identical dimensions. The present work reflects this energy optimization by simultaneous tailoring of both the fields in order to obtain absorption and emission spectra.
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Theoretical computation of eigenenergy and transmission coefficient for symmetric quantum double barrier structure considering GaAs/Al xGa 1-xAs material composition has been carried out using transfer matrix method to study the resonant... more
Theoretical computation of eigenenergy and transmission coefficient for symmetric quantum double barrier structure considering GaAs/Al xGa 1-xAs material composition has been carried out using transfer matrix method to study the resonant tunneling phenomenon under 1-D confinement which is a quantum-coherent mechanism, and also to study about the existence of quasi-bound states when the device is subjected to electric field. Device is made dimensionally asymmetric to observe the variation of tunneling probability in presence and absence of electric field to compute probability of resonant tunneling at specific energy values less than barrier potential.. Effective mass mismatch at junctions are considered throughout the analysis by varying the mole fraction of Al to estimate near accurate values of eigenenrgies and also of the transmission probabilities. Application of negative bias makes the possibility of quasi- bound states near zero energy.
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Transconductance of high electron mobility transistor is analytically computed by simultaneously solving Poisson's equation and carrier density equations subject to appropriate boundary conditions in nanometric dimension. Static and... more
Transconductance of high electron mobility transistor is analytically computed by simultaneously solving Poisson's equation and carrier density equations subject to appropriate boundary conditions in nanometric dimension. Static and transfer characteristics are obtained for low biasing ranges from which device transconductance is computed. External biases, threshold voltage of the device and source and drain resistances are considered to analyze the effect on device transconductance. Peaks of the transconductance plots are obtained at lower V GS, and decreasing nature is seen at with increase of vertical bias. Results are suitable for using the device as amplifier in nanoelectronic circuit.
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The subthreshold slope of a submicron high-electron-mobility transistor (HEMT) is analytically computed as a function of vertical electric field for various parasitic effects and structural parameters. The simultaneous solution of... more
The subthreshold slope of a submicron high-electron-mobility transistor (HEMT) is analytically computed as a function of vertical electric field for various parasitic effects and structural parameters. The simultaneous solution of Poisson’s equation and the carrier density equation provides drain current from which subthreshold slope is calculated subject to appropriate boundary conditions. Simulation is carried out at optimised channel length and applied bias for which maximum transconductance and higher differential conductance are already reported. Results show that for a particular range of gate-to-source bias, V GS, simulated findings match very closely to the ideal value of 60 mV/decade. The role of an aluminium nitride (AlN) buffer layer in tailoring the subthreshold slope magnitude is critical and the effect of submicron channel length, which is otherwise absent in conventional HEMTs, is explored. A combination of both the electric fields in realistic situations is investiga...
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Optical bandwidth of bandpass filter with metamaterial based defected one-dimensional photonic crystal is analytically computed. Two different metamaterial namely parallel nanorod and nano-fishnet with elliptical void are considered for... more
Optical bandwidth of bandpass filter with metamaterial based defected one-dimensional photonic crystal is analytically computed. Two different metamaterial namely parallel nanorod and nano-fishnet with elliptical void are considered for the design of bandpass filter, and both normal and oblique incidences (with all types of polarization) are considered for analyzing performance. Defect density is considered within practical limit for making the simulated output of practical importance. Structural parameters are tuned within fabrication limit, and angle of incidence are also tuned within feasible limit for which bandwidth is determined. Theoretical findings have practical importance as filter with sub-micron bandwidth can be utilized in all-optical integrated circuit.Optical bandwidth of bandpass filter with metamaterial based defected one-dimensional photonic crystal is analytically computed. Two different metamaterial namely parallel nanorod and nano-fishnet with elliptical void are considered for the design of bandpass filter, and both normal and oblique incidences (with all types of polarization) are considered for analyzing performance. Defect density is considered within practical limit for making the simulated output of practical importance. Structural parameters are tuned within fabrication limit, and angle of incidence are also tuned within feasible limit for which bandwidth is determined. Theoretical findings have practical importance as filter with sub-micron bandwidth can be utilized in all-optical integrated circuit.
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Filters in all-optical circuit have the potential advantage over that of optoelectronic circuits because of very high SNR, thanks to the reduced scattering between photons instead of electron-electron collisions. This property makes the... more
Filters in all-optical circuit have the potential advantage over that of optoelectronic circuits because of very high SNR, thanks to the reduced scattering between photons instead of electron-electron collisions. This property makes the PhC based filters as the blue-eyed candidate for optical signal processing in photonic circuits. Semiconductor heterostructures are in general the constituent element of photonic crystal (PhC) based devices, whose performance is characterized by passband width at the desired frequency of communication spectrum, along with magnitude of ripple in that region of interest. The present paper shows that effect of device temperature has a great deal of influence on the performance parameters of the filter, under different polarized conditions and different magnitudes of structural parameters within physically realizable limit. But modulation of bandwidth is negligibly small as observed from simulated results within the choice of temperature range. Results are critically constructive for inclusion of this filter in optical integrated circuit.
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Insertion loss, isolation factor and return loss of one-bit RF MEMS switch designed at higher microwave frequency ranges is numerically measured for computation of up-state and down-state capacitance. SiO2 is the material considered for... more
Insertion loss, isolation factor and return loss of one-bit RF MEMS switch designed at higher microwave frequency ranges is numerically measured for computation of up-state and down-state capacitance. SiO2 is the material considered for design purpose and simulation is performed over the entire microwave frequency range in order to investigate the position of maximum loss (peak point). Overlap cross-sectional area is varied over the possible fabrication range, and losses are measured for both actuated as well as unactuated states of the device over the varying overlap region. Both up and down state capacitances are measured which are higher with increase of active area. Return loss of −50 dB is observed for unactuated state whereas it becomes very low (~ −7.5 dB) for actuated device. Also for down state capacitance measurement, isolation increases upto −40 dB. Results are very useful for phase-shifter design at microwave spectrum.
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Subthreshold current for heterostructure pMOSFET is analytically explored as a function of applied bias for Si-SixGe1-x material system in presence of band-to-band tunneling. Threshold voltage of the structure is calculated considering... more
Subthreshold current for heterostructure pMOSFET is analytically explored as a function of applied bias for Si-SixGe1-x material system in presence of band-to-band tunneling. Threshold voltage of the structure is calculated considering body effect for different structural parameters, and mole fraction of Ge is chosen as 0.28 for that operating point where 2DEG is yet to be formed, and thus suitable for estimating subthreshold conduction. Using this optimum structure, BTBT effect is incorporated to measure the drain current for a range of source-to-gate voltage (VSG), and results suits in excellent with available experimental data for very low and higher values of source-to-drain voltage (VSD). Result is also computed in absence of tunneling effect, and drastic variation is observed which speaks in favor of our proposed model of subthreshold conduction. A monotonic decrease of subthreshold slope is observed with increase of VSG, which speaks for the optimum biasing criteria for operation of the device in order to minimize the leakage current. Results are in favor of applying the model for sub-22 nm FinFET or even sub-10 nm TFET devices.
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In this paper, millimeter-wave signals are generated with characteristics of high gain and low noise using optical frequency comb, where generated signals are tunable at a wider range (approx 50 GHz in both the sides) around the central... more
In this paper, millimeter-wave signals are generated with characteristics of high gain and low noise using optical frequency comb, where generated signals are tunable at a wider range (approx 50 GHz in both the sides) around the central frequency 94 GHz. Concept of electrical mixing is incorporated to achieve the tuning of the signals. Result shows that adopted methodology is far superior to conventional optical mixing and stable, high gain and low noise microwave signals are obtained in all the tuned frequencies. Wider tuning range speaks about the supremacy of the proposed scheme both in optical as well as in RF spectrum.
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Threshold voltage (with and without body bias) for heterostructure pMOSFET is analytically explored as a function of applied bias for Si-SixGe1-x material system in presence of band-to-band tunneling. Threshold voltage for given device... more
Threshold voltage (with and without body bias) for heterostructure pMOSFET is analytically explored as a function of applied bias for Si-SixGe1-x material system in presence of band-to-band tunneling. Threshold voltage for given device structure is calculated in the light of body effect for different structural parameters, and mole fraction of Ge is chosen as 0.28 for that operating point where 2DEG is yet to be formed, and thus making it apposite for estimating subthreshold conduction. Using this optimum structure, BTBT effect is incorporated to quantity the variation of threshold voltage over a range of source-to-gate voltages (VSG). The results accord with available experimental data for very low and higher values of source-to-drain voltage (VSD). Result is also computed in absence of tunneling effect, and drastic variation is observed which speaks in favor of our proposed model of subthreshold conduction which can be further extended for modeling of sub-threshold drain current characteristics of HFETs.
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Drain-to-source current of independently-driven double gate (ID-DG) MOSFET is analytically computed following Ortiz-Conde model in sub 100 nm channel length in presence of different high-K dielectrics. Fowler-Nordheim tunneling concept is... more
Drain-to-source current of independently-driven double gate (ID-DG) MOSFET is analytically computed following Ortiz-Conde model in sub 100 nm channel length in presence of different high-K dielectrics. Fowler-Nordheim tunneling concept is invoked due to reduced dielectric thickness; and front gate control is tailored to analyze the effect on current and pinch-off voltage. Excellent agreement is observed with published literatures for high front-gate voltage when device is lightly doped; which speaks in favor of the work within dimensional constraints. Percentage change of current considering body effect is estimated for different gate bias. Result speaks in favor of low power analog applications.
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Fill factor and conversion efficiency of single heterojunction solar cell is analytically computed based on the shallow doping at GaAs quantum well region. Poisson’s equation is solved with suitable boundary condition applied at... more
Fill factor and conversion efficiency of single heterojunction solar cell is analytically computed based on the shallow doping at GaAs quantum well region. Poisson’s equation is solved with suitable boundary condition applied at hetero-interface for both dark and illuminated conditions, corresponding to which open-circuit voltage and short-circuit current are computed. Realistic dependence of minority carrier distribution on material layers and diffusion widths are taken into account for simulation purpose. Result exhibits that variation of acceptor density leads to better outcome in terms of both efficiency and fill factor, which is also critically depends on length of quantum well region. Doping of AlGaAs barrier layer has negligible influence on fill factor and conversion efficiency. Optimized dimension of quantum well layer width is the critical parameter for design of efficient solar cell, as revealed from the analysis.
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Transmissivity of 1D defected photonic crystal is computed using transfer-matrix technique as function of wavelength for TM and TE mode of propagations. Layer dimensions and incidence angle are varied within practical range to study the... more
Transmissivity of 1D defected photonic crystal is computed using transfer-matrix technique as function of wavelength for TM and TE mode of propagations. Layer dimensions and incidence angle are varied within practical range to study the change in wave propagation characteristics computed around 1.55 µm. Normalized defect density is varied within acceptable limit to observe the variation of transmission, which plays key role for application of the structure as band-pass filter. Results revel that defected crystal can be implemented in designing photonic b.p.f with acceptable passband width and confinement at the cut-off frequencies for optical communication.
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Drain current and pinch-off voltage of ultrathin double-gate MOSFET are analytically calculated based on Taur’s model, where the centre potential is derived from Ortiz-Conde formulation. Drain current is computed for different structural... more
Drain current and pinch-off voltage of ultrathin double-gate MOSFET are analytically calculated based on Taur’s model, where the centre potential is derived from Ortiz-Conde formulation. Drain current is computed for different structural parameters in lower nanometric range, and the effect of the high-K dielectric is investigated. Pinch-off voltage shift is therefore derived from the simulated findings and compared with the available findings followed by Ortiz-Conde. The result shows a measurable variation in the parameters, and the root cause is explained from the electrostatic point of view. Findings are important for conductance calculation.
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Spectral response of GaAs solar cell is analytically computed incorporating the existence of quasi-Fermi level generated after photon shower. Analytical computation is carried out for simultaneous solution of continuity equations and... more
Spectral response of GaAs solar cell is analytically computed incorporating the existence of quasi-Fermi level generated after photon shower. Analytical computation is carried out for simultaneous solution of continuity equations and diffusion equations, and contribution of drift is also taken into account. Results are obtained by varying structural parameters within lower photon energy range to obtain higher response magnitude.
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Complete electromagnetic bandgap is analytically computed for parallel nanorod structure when placed inside a triangular lattice in symmetric fashion. Being a metamaterial or double negative refractive index material, this structure... more
Complete electromagnetic bandgap is analytically computed for parallel nanorod structure when placed inside a triangular lattice in symmetric fashion. Being a metamaterial or double negative refractive index material, this structure exhibits tunable bandgap when dimension of the cylinder, i.e., fill factor of the structure is changed within feasible mechanical limit. Formation of bandgap becomes only possible for magnetic polarization, whereas even quasi bandgap is not observed for electric polarization. Maximum bandgap width is obtained for 0.45 value of normalized radius of the nanorod, and corresponding midband frequency is computed. Field patterns are also obtained for the desired frequency values. Maximum and minimum bandgap inside first Brillouin zone is calculated which plays critical role for photonic filter design.
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Characteristic impedance of MIM surface plasmon structure is analytically computed from the knowledge of propagation vector variation for different nanometric structural dimensions. Length, width, and distance between metal plates are... more
Characteristic impedance of MIM surface plasmon structure is analytically computed from the knowledge of propagation vector variation for different nanometric structural dimensions. Length, width, and distance between metal plates are kept in nanometer range to evaluate the propagation vector in high frequency domain, and effect of both Faraday inductance and kinetic inductance are incorporated. Notch in impedance profile is observed due to the modulation of surface plasmon propagation vector w.r.t dielectric propagation vector, and position of notch can suitably be tailored by proper choice of dimensions and material. Result provides accurate indirect measurement of the skin depth of the structure.