Md. Monjarul
@iu.ac.bd
Professor, Dept.of Electrical and Electronic Engineering
Islamic University
RESEARCH, TEACHING, or OTHER INTERESTS
Materials Science, General Materials Science, Polymers and Plastics, Renewable Energy, Sustainability and the Environment
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Habibullah Khan, Md. Monirul Islam, Rajnin Imran Roya, Sariha Noor Azad, and Mahbub Alam
MDPI AG
Graphyne has attractive electronic properties that make it a possible replacement of silicon in FET technology. In FET technology, the goal is to achieve low power dissipation and lower subthreshold swing. In this study, we focused on achieving these goals and studied the electronic properties of α-graphyne nanoribbons. We simulated the transfer and output characteristics of an α-graphyne ballistic nanoribbon FET. We used the tight-binding model with nearest-neighbor approximation to obtain the band structure which gives the same band structure as the one found from the DFT. In order to simulate the I-V characteristics of the transistor we used the non-equilibrium Green’s function (NEGF) formalism. The results show that the modeled FET can provide a high Ion/Ioff ratio and low subthreshold swing. We also studied the effects of defects as defects cannot be avoided in any practical device. The study shows that the Ion/Ioff ratio and subthreshold swing improves as defects are added, but the delay time and dynamic power dissipation worsen.
Z. Ahmed, Tareq Rahman, K.M.A. Hussain, M.T. Khatun, M.S.S. Chowdhury, T. Faruqe, F.T.Z. Toma, Y. Ahmed, M.N.I. Khan, and M.M. Alam
IOS Press
Zinc Sulphide is one of most studied semiconductor with wide band gap (3.5–3.9 eV) versatile material due to its physical and chemical properties. ZnS is a non-toxic material and a suitable candidate to be a buffer layer for heterojunction solar cells. In this study, Zinc Sulphide (ZnS) thin films were deposited by chemical bath deposition technique using Zinc Acetate Dihydrate [Zn (CH3COO)2. 2H2O] and Thiourea [CH4N2S]. The ZnS thin films samples were characterized by UV-Vis NIR Spectroscopy, X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDX), Fourier-Transform Infrared Spectroscopy (FTIR) and Thin-Film Measurement Instrument. FTIR spectra confirmed the presence of ZnS bond in the crystalline thin film. XRD data confirmed the cubic structure of the deposited thin film only when the amount of Thiourea was increased and the complexing agent Hydrazine Hydrate was replaced with Tri-Sodium Citrate. Crystallite size and strain were estimated using Debye-Scherrer model and Williamson-Hall model and lattice constant was estimated using Nelson-Riley plot. Otherwise, XRD showed the amorphous phase. UV-Vis data confirmed ZnS thin films as enough transmittive and it showed higher bandgap. Thin-Film Measurement Instrument was used to measure the thickness of the ZnS thin films. Synthesized ZnS thin films exhibited promising characteristics for using as the buffer layer of the heterojunction solar cells. Highlights • ZnS thin films were prepared successfully by simple, low cost and environment friendly chemical bath deposition method. • XRD measurement confirmed both Amorphous and Crystalline phase of ZnS thin films. • By changing the precursor only can be achieved crystalline phase from amorphous phase of ZnS thin film. • The amount of precursor and deposition conditions can be optimized to produce crystalline ZnS thin film.
Md. Johurul Islam, Kamaruzzaman, Md. Forhad Hossain, Md. Abdul Awal, Md. Rezwanur Rahman, and M. M. Alam
AIP Publishing
Currently, eco-friendly, cost-effective, and simple synthesis techniques are drawing the attention of nanoparticle researchers. The conversion of silver ions to silver nanoparticles (AgNPs) is carried out using the Adenia trilobata leaf extract, which is capable of acting as an exclusive reducing agent. AgNPs show very crucial antibacterial properties and are nontoxic for humans. The color of the solution changes from light blue to brown, ensuring the formation on nanoparticles. The biosynthesized AgNPs are incorporated into cotton fiber, and their antibacterial activity on gram negative (E. coli) bacteria has been studied. The UV/Vis and absorption spectroscopy analysis shows a surface plasmon resonance peak at 445 nm. The x-ray diffraction measurement reveals peaks at 38.02 and 44.23, and the average particle size is 18.30 nm. Field emission scanning electron microscopy has been performed to find the size, shape, and morphology of the treated nanoparticles and the AgNP-incorporated cotton fiber. The Fourier transform infrared spectroscopy result shows the presence of functional groups of AgNPs and capping agents. The antibacterial activity on gram negative (E. coli) bacterial strains for the both cases showed a promising result.
M. N. Uddin, M. M. Uddin, and M. M. Alam
Universiti Putra Malaysia
Numerical predictions of blood flow and hemodynamic properties through stenosis and aneurysm artery have been studied in the presence of blood clots at the constricted area. The finite element method has been used to solve the partial differential equations of continuity, momentum, Oldroyd-B, and bioheat transport in cartesian coordinates systems. The present investigation carries the potential to compute blood velocity, pressure, and drag coefficients with significance at the throat of stenosis and aneurysm. The models have also been employed to study simulation, blood clots, and hemodynamic characteristics for all modifications. The impact of shearthinning on blood flow is intensified compared to the viscoelastic properties. It is found that the maximum effect of the drag coefficient is visible at the hub of stenotic for nonclotting models. The highest pressure and the lowest velocity are gained for the presence of blood clots at the constraint area. The impact of stenosis and aneurysm artery, drag coefficient, and blood clots on blood flow is the main physical outcome that may be reported in medical science to identify atherosclerosis diseases. The quantitative analysis has been completed numerically with the physiological significance of hemodynamic factors of blood flow which shows the validity of the present model.
Dhiman Roy and Mahbub Alam
IEEE
To reduce energy dissipation in field-effect transistors on low-power applications such as switches, we have modeled a transistor made of 2D topological insulator zigzag stanene nanoribbon based on electric field-induced topological phase transition, which turns on and off the device. The transport properties and the device’s important parameters have been calculated by the tight-binding model and Non-Equilibrium Green’s Function formalism. The results show high on-state current density which can flow ballistically even in the presence of impurities and ultra-low dynamic power dissipation. Therefore, proof of the concept of the energy-efficient topological transistor is presented.
Ashique E Elahi Sadi, Mahfuzur Rahman Munna, and Mahbub Alam
IEEE
The graphene nanoribbon-based resonant-tunneling diodes (RTDs) have lately grabbed the interest of numerous scientists. In this paper, we have investigated the performance of double and triple-barrier hetero-structure armchair graphene nanoribbon (AGNR) RTD and made a comparison between them. The investigation shows that triple barrier hetero-structure (TBHS) RTD has superior characteristics in terms of peak-to-valley current ratio (PVR) and power dissipated at the valley current. In addition, we compared the performance of the double barrier hetero-structure (DBHS) with the electrostatically doped (ED) AGNR RTD. We discover that the hetero-structure RTD has a superior peak-to-valley current ratio and valley current power dissipation characteristics. Our article also examines the effect of a single vacancy defect in the barrier and well regions of a double barrier hetero-structure (DBHS) AGNR RTD. Introducing a single vacancy defect in the well region decreases the PVR and increases the power dissipated at the valley current. Introducing a single vacancy defect in the barrier area, on the other hand, enhances the PVR and lowers the power wasted by the valley current.
Rudra Biswas and Mahbub Alam
IEEE
This paper presents a study on the modeling of nanoscale MESFET. The proposed structure uses a Schottky barrier or rectifying contact to reduce fabrication inconvenience by removing the necessity of an oxide layer in a FET. So, it can be an attractive alternative to a typical MOSFET. Modeling the structure in nanoscale ensures minimum transistor size and maximum transistor density in a chip. Ensuring the small dimension of the device, the proposed design has been simulated with COMSOL Multiphysics simulator. The paper also focuses on studying the structure with a variation of materials used as substrate. I-V characteristics like drain current vs. drain to source voltage and drain current vs. gate to source voltage of various materials are investigated. Device performance based on switching ratio is also compared in this study. By using high mobility material, a better switching ratio can be achieved. Due to fast switching, the device can find its usage in high frequency and low power applications.
Ashique E Elahi Sadi, Mahfuzur Rahman Munna, and Mahbub Alam
IEEE
Graphene has sparked a lot of interest due to its unique physical and electrical properties and emerged as a possible silicon replacement in FET technology. In this paper, the transfer and output characteristics of an electrostatically doped (ED) 7 Armchair Graphene Nanoribbon 10 nm (channel) FET (AGNR- FET) and the transfer characteristics of different (3m & 3m+1 where m is a positive integer) AGNR-FETs (10 nm channel) with three gates are investigated. The atomic interaction between carbon atoms is described by the tight-binding model with the nearest-neighbor approximation. The Poisson and Schrodinger equations are self-consistently solved within the non-equilibrium Green’s function (NEGF) formalism to simulate the characteristics of the transistors. Results show that a single vacancy (SV) defect at the center of the channel region significantly increases the ION/IOFF ratio and decreases the subthreshold swing for both 3m & (3m+1) AGNR-FET. For every value of m, the (3m+1) AGNR-FET provides a higher ION/IOFF ratio and lower subthreshold swing than 3m AGNR-FET for both cases with or without defect.
Md. Nasir Uddin, Md. Abdul Alim, Md. Mashud Karim, and Md. Monjarul Alam
Bangladesh Journals Online (JOL)
Blood flow in a double aneurysmatic artery of the normal tissue is studied. A Finite Element method is used to analyze numerical simulation of blood flow through aneurysmatic arteries. The Newtonian, generalized Newtonian, Oldroyd-B and generalized Oldroyd-B models are considered due to the behavior of blood viscosity. In this paper, the effect of aneurysmatic artery on blood flow with permeability in human organ has been investigated. The non-Newtonian models have been applied to study the blood velocity, pressure, and wall shear stress in an aneurysmatic artery. A set of partial differential equations are transformed into dimensionless equations using non-dimensional variables and solved numerically. We have focused our consideration on the simulation of blood velocity and pressure in terms of blood flow rate for various Weissenberg numbers (Wi) and Peclet numbers (Pe). The important effects on blood flow of aneursymatic artery for blood velocity, pressure and wall stress profiles are presented graphically for Newtonian and non-Newtonian models.
Md. Johurul Islam, M. T. Khatun, Md. Rezwanur Rahman, and M. M. Alam
AIP Publishing
In this research, the ability of the leaf extract of Justicia adhatoda is observed as a unique reducing agent for bioconversion of copper ions to copper oxide nanoparticles (CuO NPs). CuO NPs have significant antibacterial activity and nontoxicity toward humans. The formation of nanoparticles is confirmed by the color change of the solution from light blue to brown because of the trouble of surface plasmon resonance (SPR). The optical study showed an SPR peak at 280 nm. The interaction of CuO NPs excipients with the biomolecules is studied using x-ray diffraction and particle size is also calculated. Field emission scanning electron microscopy has been applied to recognize the size, shape, and morphology of nanoparticles, which is incorporated in cotton. Fourier transform infrared spectroscopy showed that the reduction of CuO NPs was due to the biomolecules present in the leaf extract, which acted as reducing, in addition to capping, agents. The synthesized CuO NPs-coated cotton were tested for antibacterial activity to both gram-positive and gram-negative bacterial strains, which are applicable for the fabrication of an antibacterial cotton textile.
Md. Johurul Islam, M. Jhahan, M. T. Khatun, M. N. I. Khan, Mohammad Jellur Rahman, Md. Aminul Islam, Abdullah Al-Momin, and M. M. Alam
Springer Science and Business Media LLC
Tanvir Hossain, Md Istiaque Rahaman, and Mahbub Alam
IOP Publishing
Resonant tunneling phenomena are explored using armchair graphene nanoribbon (AGNR), which eliminates the lattice mismatch and electron mobility degradation problems of conventional heterostructure resonant tunneling diodes (RTDs). Eight antidote topologies are proposed in this paper. These antidote topologies significantly increase or decrease the band gap of AGNR. Both double barrier quantum well and single barrier quantum well structures have been achieved by putting the antidote-induced AGNRs and pristine AGNRs. A numerical approach with a tight binding model and non-equilibrium Green’s function formalism has been used to simulate the quantum phenomena of the device. Current–voltage characteristics of these proposed RTDs show a high peak to valley ratio and low power dissipation with respect to different antidote topologies. Channel length variation effects are investigated in the proposed RTDs, and it is found that the peak to valley ratio, valley current, valley voltage, and power dissipation can be improved by tuning the channel length. These graphene-based RTDs are easy to fabricate and offer more flexibility in terms of peak to valley ratio, valley current, valley voltage, and power dissipation.
MdIstiaque Rahaman and Mahbub Alam
Elsevier BV
Tanvir Ahmed Masum, Beig Rajibul Hasan, Nishat Mahzabin Helaly, Anowarul Azim, and Mahbub Alam
Springer Science and Business Media LLC
Joy Sharma, Nishat Mahzabin Helaly, and Mahbub Alam
IEEE
The quantum transport properties of electrons in 2D hexagonal lattice Molybdenum di-selenide (MoSe2) armchair and zigzag nanoribbons are investigated using Non-Equilibrium Green’s function (NEGF) formalism and 11- band Tight-Binding model. The armchair nanoribbon shows presence of bandgap while the zigzag nanoribbon shows edge states in a single edge with Dirac like E-K diagram.
Nazmul Amin and Mahbub Alam
IEEE
In this article, the edge transport of Zigzag Graphene NanoRibbon (ZGNR) in the presence of an abrupt structure change due to missing atoms, which we define as ‘cut’ is studied through Non-Equilibrium Green’s Function formalism. Interesting results are found that are notably different for difference in the width of the ‘cut’. For ZGNR, depending on the width of the ‘cut’, the electrons can be fully transmitted (T = 1) or fully blocked (T = 0) in the device scattering region.
Anowarul Azim, Beig Rajibul Hasan, Nishat Mahzabin Helaly, Tanvir Ahmed, and Mahbub Alam
IEEE
2D Topological insulators (TIs) possess an unique property of transport of spin edge states which are topologically protected. This phenomenon is explored in details in this paper for random edge imperfections in 2D hexagonal lattice nanoribbon TIs using Non equilibrium greens function (NEGF) formalism. Haldane model has been used for incorporating spin orbit interaction in the device hamiltonian, which is the source of creating topologically protected edge states in these materials.
Md. Istiaque Rahaman, Md. Istiaque Rahaman, Mahbub Alam, and Mahbub Alam
IEEE
Electron transport characteristics in 2D hexagonal lattice Nanoribbon Topological Insulator was investigated using Non Equilibrium Green's Function (NEGF) method, under the influence of random potential barrier, applied in full transverse direction in the path of movement of electron. Unlike ordinary 2D hexagonal lattice nanoribbons, Topological Insulators can retain their ballistic nature of electron transport. This robust behavior of Topological Insulators can be exploited in making next generation TI based electronic, optoelectronic devices and interconnects.
Beig Rajibul Hasan, Tanvir Ahmed Masum, Nishat Mahzabin Helaly, Anowarul Azim, Joy Sharma, and Mahbub Alam
IEEE
Electron transport properties in 2D hexagonal lattice topological insulators (TI) under photon interaction are investigated using Non Equilibrium Green's Function (NEGF) formalism and Haldane model. Back scattering less transport of electrons in valence band and conduction band (after photo-excitation) is observed. The result of this research can be utilized for design of nano-scale optoelectronic coherent electron devices.
Shaid Hasan, Nashmin Alam, Nazmul Amin, and Mahbub Alam
IEEE
Ballistic and coherent transport is an emerging field of research for nanoscale electronic and optoelectronic devices [1]. In this work, we have investigated coherent electron transport in zigzag graphene nanoribbon (ZGNR) for elastic phonon dephasing. A comparison between two phonon dephasing mechanism which are momentum conserving mechanism and momentum relaxing mechanism has also been investigated in our work. This work deepens our understanding of quantum elastic dephasing process and will be helpful for designing future coherent nano electronic devices.
Nazmul Amin, Mushita Masnd Munia, Abu Mohammad Saffat-Ee Huq, and Mahbub Alam
IEEE
With device length approaching sub-10nm region in present day transistors, the coherent nature of electron cannot be overlooked, in this paper, we investigate the coherent electron transport under phonon dephasing for Armchair Graphene Nanoribbon (AGNR) which is a possible candidate material for future electronics.
Mahbub Alam and Paul L. Voss
OSA
Recent plasmonics experiments focus light to 10 nm focal spots. We show that with such illumination, electrostatically gated graphene nanoribbon photoconductors produce photocurrents whose direction depends on illumination wavelength.
M.M. Alam, S. Daniels, and P.J. McNally
Elsevier BV
Mahbub Alam and Paul L. Voss
OSA
We study nanoscale optical illumination of semiconducting armchair graphene nanoribbons. The optical absorption undergoes a sharp transition to the long-ribbon limit at approximately the de Broglie wavelength of the valence band electrons.