Browsing by Author "S. Jit"

Now showing 1 - 9 of 9

A two-dimensional model for the surface potential and subthreshold current of doped Double-Gate (DG) MOSFETs with a vertical Gaussian-like doping profile
(2010) Sarvesh Dubey; Pramod Kumar Tiwari; S. Jit
An analytical two-dimensional (2D) model for the surface potential distribution and subthreshold current of the Double-Gate (DG) MOSFETs having Gaussian-like doping profile in the vertical direction of the silicon channel has been presented in this paper. The model is based on the solution of the 2D Poisson's equation in the fully depleted channel region using evanescent method. The effect of doping profile parameters on the surface potential has also been presented. The potential distribution function has been utilized to investigate the subthreshold current characteristics of the device. The validity of the proposed model is shown by comparing the analytical results with the simulation data obtained by the 2D device simulator ATLAS™. The proposed model is considered to be a very accurate and compact one since it does not include any fitting parameter. Copyright © 2010 American Scientific Publishers.
An analytical drain current model for short-channel triple-material double-gate MOSFETs
(2011) Harshit Agnihotri; Abhishek Ranjan; Pramod Kumar Tiwari; S. Jit
In this paper, a strong inversion drain current model incorporating various effects such as channel length modulation has been developed for a short-channel symmetrical triple material-double gate (TM-DG) MOSFET based on the drift current equation. The model results have been compared with the simulation data obtained by using the commercially available device simulation software ATLAS™. © 2011 IEEE.
Analysis of ternary layer photonic band gap tunable filters for wavelength division multiplexing applications
(American Scientific Publishers, 2017) Amritanshu Pandey; Archana Tripathi; Raghavi; S.K. Srivastava; S. Jit
In this paper, we have proposed a ternary layer photonic band gap structure as a versatile optical filter for various WDM applications. The design of a versatile optical filter has been done using Photonic Band Gap (PBG) structure for all Wavelength Division Multiplexing (WDM) applications including Coarse Wavelength Division Multiplexing (CWDM) and Dense Wavelength Division Multiplexing (DWDM). The proposed optical filter is a one-dimensional ternary periodic structure with a linearly periodic refractive index profile. It can be tuned by varying lattice parameters and angle of incidence. The filters are designed in the S band of EM spectrum, around 1310 nm wavelength, which can be used in CWDM applications at transmitter and receiver side of the network. Similarly in the C-Band of EM spectrum, near 1550 nm wavelength, filter with 0.4 nm pass band are designed. For DWDM applications, separation between neighboring wavelength channels is less than 1 nm and so the width of the pass band of an individual filter must be less than 0.5 nm. Therefore the filter designed for the C band can be used in DWDM applications. Thus the proposed filter design technique covers all the different ranges of WDM applications. © Copyright 2017 by American Scientific Publishers.
Catalyst free growth of ZnO nanorods by thermal evaporation method
(2013) Divya Somvanshi; S. Jit
In this work, we report catalyst free growth of ZnO nanorods on n-Si substrate by a low cost thermal evaporation method. The surface morphology, chemical composition and crystalline structure of ZnO nanorods have been determined by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) spectroscopy respectively. It is found that, the as -deposited ZnO seed layer reduces lattice mismatching between ZnO and Si from 40.3 to 0.28%, therefore enhances the subsequent growth and crystalline quality of ZnO nanorods on Si substrate. The present methodology is simple, cost effective and highly applicable for synthesis of ZnO nanorods for optoelectronics applications. © 2013 AIP Publishing LLC.
Effects of annealing temperature on the structural, optical, and electrical properties of ZnO thin films grown on n-Si〈100〉 substrates by the sol-gel spin coating method
(Chinese Society for Metals, 2014) Aniruddh Bahadur Yadav; Amritanshu Pandey; S. Jit
The effects of annealing temperature on the sol-gel-derived ZnO thin films deposited on n-S〈100〉 substrates by sol-gel spin coating method have been studied in this paper. The structural, optical, and electrical properties of ZnO thin films annealed at 450, 550, and 650 °C in the Ar gas atmosphere have been investigated in a systematic way. The XRD analysis shows a polycrystalline nature of the films at all three annealing temperatures. Further, the crystallite size is observed to be increased with the annealing temperature, whereas the positions of various peaks in the XRD spectra are found to be red-shifted with the temperature. The surface morphology studied through the scanning electron microscopy measurements shows a uniform distribution of ZnO nanoparticles over the entire Si substrates of enhanced grain sizes with the annealing temperature. Optical properties investigated by photoluminescence spectroscopy shows an optical band gap varying in the range of 3.28-3.15 eV as annealing temperature is increased from 450 to 650 °C, respectively. The four-point probe measurement shows a decrease in resistivity from 2.1 × 10 -2 to 8.1 × 10-4 ω cm with the increased temperature from 450 to 650 °C. The study could be useful for studying the sol-gel-derived ZnO thin film-based devices for various electronic, optoelectronic, and gas sensing applications. © 2014 The Chinese Society for Metals and Springer-Verlag Berlin Heidelberg.
Electrical characteristics of Si/ZnO core-shell nanowire heterojunction diode
(Springer Science and Business Media Deutschland GmbH, 2014) Purnima Hazra; S. Jit
In this paper, we have presented the electrical characteristics of the silicon nanowire (SiNW)/ Zinc oxide (ZnO) core-shell heterojunction diode. In this work ZnO thin film was conformally deposited by atomic layer deposition (ALD) method on vertically-aligned SiNW arrays, fabricated by electroless metal deposition and etching method with the help of ultrasonication. The current-voltage and capacitance-voltage characteristics were measured to show the electronic properties of the device. The current-voltage characteristics show the nonlinear rectifying nature of the SiNW/ZnO core-shell heterojunction diode with ideality factor and barrier height of 3.2 and 0.68 eV respectively. The barrier height measured from C-V characteristics is 0.97 V. The difference between barrier heights calculated from both I-V and C-V characteristics show that barrier inhomogeneities can be present between the interface of Si and ZnO. However, the satisfactory performance of junction characteristics ideality factor and turn-on voltage of the Si/ZnO core-shell heterojunction diodes indicates their potential applications in optoelectronics and photonics. © Springer International Publishing Switzerland 2014.
Fabrication and characterization of p-type SiNW/n-type ZnO heterostructure for optoelectronics application
(Institute of Physics Publishing, 2015) Purnima Hazra; P. Chakrabarti; S. Jit
Semiconductor hybrid structure, known as core-shell heterostructures was fabricated and optical properties were analyzed to make it applicable in future optoelectronic and photonic devices. Large-area, high density, vertically oriented silicon nanowire arrays, synthesized by means of metal-assisted chemical etching of p-type silicon (100) substrate was used as the core and zinc oxide (ZnO) layer, deposited on the SiNW arrays by atomic layer deposition (ALD) was used as shell. The XRD peaks of the heterostructure confirmed the subsequent growth of ZnO film on the template of SiNW arrays having similar crystalline quality. The photoluminescence (PL) spectra showed a very sharp peak at 378 nm, corresponding to the band gap of ZnO material and another broad emission band almost throughout the entire visible range with a peak around 550 nm. The structure also showed a very good antireflection property. The results present that the SiNW/ZnO heterostructure can have potential application in future nanoscale electronic and photonic devices. © Published under licence by IOP Publishing Ltd.
Modeling of photodependent capacitance for short gate-length ion-implanted GaAs MESFETs
(SPIE, 2012) Shweta Tripathi; S. Jit
This paper presents an analytical model for C-V characteristics of short gate-length GaAs MESFET under illuminated condition. The non-analytic Gaussian doping profile commonly considered for the channel doping of an ion-implanted GaAs MESFET has been replaced by an analytic Gaussian-like function for the simplicity of the present model. When the computed results of the proposed model are compared with numerical simulation data obtained by ATLAS™ device simulator, an encouraging correspondence between the two lends credibility to our model. © 2012 SPIE.
Threshold voltage model for ion-implanted short gate-length GaAs MESFETs under dark and illuminated conditions
(2011) Shweta Tripathi; S. Jit
In the present work, an attempt has been made to analytically model the threshold voltage of short-channel optically controlled GaAs MESFETs with a vertical Gaussian profile. The two-dimensional (2D) Poisson's equation has been solved with suitable boundary conditions using superposition method to obtain an optical radiation dependent threshold voltage expression. The credibility of the model is established by comparison of the calculated threshold voltage with the numerical simulation data obtained by ATLAS device simulator. © 2011 IEEE.