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[IEEE 2018 2nd International Conference on Electronics, Materials Engineering & Nano-Technology (IEMENTech) - Kolkata (2018.5.4-2018.5.5)] 2018 2nd International Conference on Electronics, Materials Engineering & Nano-Technology (IEMENTech) - Effect of Self-Consistency Technique on Current Density Profile of Resonant Tunneling Diode
摘要： This paper reveals the importance of self-consistency technique for computing current density in resonant tunneling device. AlxGa1-xAs/GaAs/AlyGa1-yAs is considered for simulation purpose, and both Schr?dinger and Poisson's equations are simultaneously solved subject to appropriate boundary conditions to obtain current density as a function of externally applied bias. Structural parameters and material compositions within type-I range are varied to get the fluctuations in current, which is otherwise absent when calculation is performed without applying self-consistency technique. Findings are significant as magnitude of current obtained is higher than that obtained when self-consistency is absent. Result has immense importance for low bias application of RTD due to the presence of peaks at particular system compositions.
关键词： Peak current density,Resonant tunneling diode,Poisson's equation,Current density,Self-consistency technique,Schrodinger's equation
更新于2025-09-23 15:22:29
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Electrical characterization of HVPE GaN containing different concentrations of carbon dopants
摘要： A comprehensive study of the electrical characteristics in Schottky diodes made of GaN:C grown by HVPE technology has been reported. The Schottky junctions were made of Ni/Au (25/200 nm) metal stack and ohmic contacts were fabricated by the Ti/Al/Ni/Au (30/90/20/100 nm) e-beam deposition of the metal thin-films followed by the rapid thermal annealing. A good quality of the fabricated Schottky diodes has been proved by considering the transient shape using a pulsed technique of the barrier evaluation under linearly increasing voltage (BELIV). The concentrations of equilibrium carriers of 1×1011 cm-3 and of 2×1010 cm-3 have been evaluated for relatively low and high carbon density doped samples, respectively, using photo-capacitance characteristics dependent on excitation intensity. The effective mobility of carriers of μeff=610 cm2/Vs has been estimated by considering the serial resistance variations dependent on excitation density, through analysis of delay times appeared in formation of peaks within BELIV transients. The optical deep level transient spectroscopy has shown that thermal emission from the rather shallow centres prevails. The centres, ascribed to vacancies as well as to carbon on Ga site, have been identified. It has been demonstrated that Schottky junctions made of heavy carbon doped (NC≥1018 cm-3) HVPE GaN material are capable to withstand voltages of ≥300 V.
关键词： barrier evaluation by linearly increasing voltage pulsed technique,transient current technique,Schottky diodes,carbon doped HVPE GaN grown on Ammono substrates,deep level transient spectroscopy
更新于2025-09-23 15:21:21
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Surface Deformation Evaluation in Dujiangyan, China Using Time-Series InSAr Technique and Multiple Temporal C-Band SAR Datasets
摘要： The surface deformation of Dujiangyan, Sichuan, China was studied. Permanent Scatterer (PS) interferometric synthetic aperture radar (InSAR) technique was applied to 21 Envisat SAR datasets acquired from May of 2008 to July of 2010 and 61 Sentinel-1 SAR datasets acquired between October of 2014 and November of 2017. The Zipingpu Dam, located on the northwestern highland area of Dujiangyan had obvious subsidence in a 2-year period after the 2008 Wenchuan earthquake. The rate ranged from 0 to –30mm/year. The quake was attributed to the major cause. From 2014 to 2017, the dam was deformed less than 5mm/year. The dam was relatively stable. Since the recovering efforts were completed before 2014, the surface deformation in the urban areas of Dujiangyan was small between 2014 and 2017. The dominant rate was about 2 to –4mm/year.
关键词： Surface deformation,Permanent Scatterer InSAR technique,Dujiangyan,Zipingpu Dam
更新于2025-09-23 15:21:21
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Leak Detection in Water Pipes Using Submersible Optical Optic-Based Pressure Sensor
摘要： Leakage is undesirable in water distribution networks, as leaky pipes are financially costly both to water utilities and consumers. The ability to detect, locate, and quantify leaks can significantly improve the service delivered. Optical fibre sensors (OFS) have previously demonstrated their capabilities in performing real-time and continuous monitoring of pipe strength leak detection. However, the challenge remains due to the high labour cost and time-consuming process for the installation of optical fibre sensors to existing buried pipelines. The aim of this paper is to evaluate the feasibility of a submersible optical fibre-based pressure sensor that can be deployed without rigid bonding to the pipeline. This paper presents a set of experiments conducted using the proposed sensing strategy for leak detection. The calibrated optical fibre device was used to monitor the internal water pressure in a pipe with simultaneous verification from a pressure gauge. Two different pressure-based leak detection methods were explored. These leak detection methods were based on hydrostatic and pressure transient responses of the optical fibre pressure sensor. Experimental results aided in evaluating the functionality, reliability, and robustness of the submersible optical fibre pressure sensor.
关键词： pipeline,leak detection,optical fibre sensors,nondestructive technique,sensors
更新于2025-09-23 15:21:21
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A novel approach for the extraction of cloud motion vectors using airglow imager measurements
摘要： The paper explores the possibility of implementing an advanced photogrammetric technique, generally employed for satellite measurements, on airglow imager, a ground-based remote sensing instrument primarily used for upper atmospheric studies, measurements of clouds for the extraction of cloud motion vectors (CMVs). The major steps involved in the algorithm remain the same, including image processing for better visualization of target elements and noise removal, identification of target cloud, setting a proper search window for target cloud tracking, estimation of cloud height, and employing 2-D cross-correlation to estimate the CMVs. Nevertheless, the implementation strategy at each step differs from that of satellite, mainly to suit airglow imager measurements. For instance, climatology of horizontal winds at the measured site has been used to fix the search window for target cloud tracking. The cloud height is estimated very accurately, as required by the algorithm, using simultaneous collocated lidar measurements. High-resolution, both in space and time (4 min), cloud imageries are employed to minimize the errors in retrieved CMVs. The derived winds are evaluated against MST radar-derived winds by considering it as a reference. A very good correspondence is seen between these two wind measurements, both showing similar wind variation. The agreement is also found to be good in both the zonal and meridional wind velocities with RMSEs < 2.4 m s?1. Finally, the strengths and limitations of the algorithm are discussed, with possible solutions, wherever required.
关键词： lidar measurements,photogrammetric technique,MST radar,cloud motion vectors,ground-based remote sensing,airglow imager
更新于2025-09-23 15:21:21
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Preparation of composite Ag@Au core–shell nanoparticles and their linear and nonlinear optical properties
摘要： We herein report the preparation of composite Ag@Au core–shell nanoparticles (NPs) through galvanic replacement reaction and the investigations of linear and nonlinear optical properties. TEM micrographs envisage the formation of core–shell NPs. EDS elemental mapping images demonstrate the homogeneous distribution of the elements and their chemical composition. The powder XRD pattern confirms the formation of highly crystalline composite Ag@Au core–shell NPs. The UV–Vis absorption spectrum shows contribution of Ag and Au characteristic absorption bands and the slight red shift provides the strong evidence for coating of Au shell over the Ag core. Moreover, the linear optical parameters such as the extinction coefficient, reflectance, refractive index, conductivity, susceptibility and polarizability are studied. z-scan analysis reveals the enhanced nonlinear optical properties of the composite Ag@Au core–shell NPs with nonlinear refraction coefficient (n2) being ten times higher than that of Ag NPs and eight times increase in comparison with that of Au NPs.
关键词： Nonlinear optical properties,Ag@Au core–shell nanoparticles,z-scan technique,Galvanic replacement reaction,Linear optical properties
更新于2025-09-23 15:21:21
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LCO-FLL control for single-phase utility integrated single-stage solar PV system
摘要： This study presents a limit cycle oscillator-frequency locked loop (LCO-FLL) control for single-phase utility integrated single-stage photovoltaic (PV) system. The proposed topology increases the utility of the voltage-source converter (VSC), particularly in the absence of PV generation. It has the potential to load harmonics current mitigation. It estimates harmonic free load current accurately with low computational requirement due to the absence of cumbersome mathematical algorithm and transformation techniques. It provides reactive power compensation, both in the absence and the presence of PV generation, improves transient response during dynamics in load and varying irradiance conditions. The total harmonic distortions of utility current and utility voltage, compliance the limit of the IEEE-519 standard. The proportional–integral (PI) regulator regulates the DC-link voltage of VSC input to the reference DC-link voltage. The incremental conductance-based technique derives the reference DC-link voltage. The dynamic behaviour of the LCO-FLL-based control is improved using a feed-forward loop for the PV power sharing. It also reduces loading on the PI controller. Test results demonstrate satisfactory performance of LCO-FLL-based control.
关键词： single-stage solar PV system,LCO-FLL control,proportional–integral (PI) regulator,incremental conductance-based technique,feed-forward loop,reactive power compensation,voltage-source converter (VSC),IEEE-519 standard,single-phase utility
更新于2025-09-23 15:21:21
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Profound optical analysis for novel amorphous Cu2FeSnS4 thin films as an absorber layer for thin film solar cells
摘要： In this study, quaternary kesterite Cu2FeSnS4 (CFTS4) has been selected due to its interesting optical and electrical characteristics. The CFTS4 films were prepared by exploiting the chemical bath deposition process at room temperature. The films were prepared at different deposition periods (1, 3, 5 and 7 h). The EDAX technique was helped in evaluating the compositional element ratio which near to 2:1:1:4. The morphology and structure of CFTS4 films have been examined by utilizing X-ray diffraction, and field emission scanning electron microscope techniques. XRD charts revealed the absence of sharp peaks and approved the amorphous nature of films under investigations. The transmittance and reflectance data were employed to compute the linear and nonlinear optical constants of the as-deposited CFTS4 films. The energy gap calculations for the CFTS4 films grown on glass substrate displayed a direct energy gap and by increasing the deposition time, a reduction in energy gap values from 1.41 to 1.19 eV was obtained. The deep analysis of linear/nonlinear optical properties as a function of deposition time has revealed many characteristics of the investigated films. Moreover, the nonlinear parameters (refractive index n2, nonlinear absorption coefficient βc and the third-order nonlinear optical susceptibility χ(3)) of the CFTS4 films were boosted with rising up the film thickness and their high values imply the possibility of utilizing these films in various optoelectronic applications.
关键词： Optical conductivity,Energy gap,Optoelectronic applications,Chemical bath deposition technique,CFTS4 thin films
更新于2025-09-23 15:21:01
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Investigating the Photovoltaic Performance of Surfactant assisted MoBi2Se5 Thin Films
摘要： MoBi2Se5 has been proved to be a promising material for the photoelectrochemical solar cell application. As, MoBi2Se5 thin films are more corrosion resistant than Bi2Se3 thin films also MoBi2Se5 can be used as a buffer layer due to its distinctive optostructural properties. In this study, we have synthesized surfactant assisted nanostructured MoBi2Se5 thin films by using cost effective chemical route, i.e. arrested precipitation technique (APT). The synthesized thin films were analyzed for their Opto-structural, surface morphological, compositional and photovoltaic application using X-ray diffraction Technique (XRD), UV-Vis Spectroscopy, Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDAX) and its photoelectrochemical solar cell performance was checked respectively. The nanocrystalline nature of MoBi2Se5 thin films was confirmed from the XRD pattern. An increment in the optical band gap energy was observed with surfactant mediation. The surface morphology of MoBi2Se5 was changed from spherical to spongy balls like nanofibrous surface morphology after surfactant assistant. Furthermore, both the as synthesized and surfactant assisted MoBi2Se5 thin films showed the photoelectrochemical solar cell applicability.
关键词： thin films,arrested precipitation technique,MoBi2Se5,surfactant,photoelectrochemical solar cell
更新于2025-09-23 15:21:01
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Influence of magnetic field orientation on laser-induced magnetization precession in Ni-Mn-Sn Heusler alloy film
摘要： Laser-induced magnetization precession is investigated in Ni-Mn-Sn Heulser alloy film using pump-probe all-optical technique. The studies are performed as a function of external magnetic field H applied at various angles with respect to the sample normal. Strong dependence of precession parameters, frequency f, amplitude A and effective damping, two precession modes, identified as Damon-Eshbach (DE) and first-order standing spin wave (PSSW) modes were observed. The values of wave vector for DE mode have been determined. The experimentally obtained exponentially decayed. The dependencies of the magnetization precession parameters have been well simulated in the frame of phenomenological approach, based on Landau-Lifshitz-Gilbert equation.
关键词： standing spin wave mode,pump-probe all-optical technique,Landau-Lifshitz-Gilbert equation,Ni-Mn-Sn Heusler alloy,Damon-Eshbach mode,Laser-induced magnetization precession
更新于2025-09-23 15:21:01