Md. Zunaid Baten

Renewable energy scenario of Bangladesh: Physical perspective

The looming energy crisis, heightened by the continuing depletion of fossil fuels, accentuates the need for deployment of renewable energy resources in Bangladesh, now more than ever before. Though hydrocarbon resources in the country are limited, the substantial availability of renewable energy sources in the form of solar, biomass, hydropower and wind energy offers opportunities of sustainable energy based development. Motivated by this auspice, the government of Bangladesh and different non-government organizations have been working towards the dissemination of renewable energy based technologies throughout the country. Though this diffusion of renewable energy sources is yet to assume extensive commercial dimensions and widespread implementations, the advancement has been significant in recent years. With the objective of reviewing this progress, this paper presents a comprehensive study of the contemporary renewable energy scenario in Bangladesh in terms of distribution, research and infrastructural development in the country. In addition to this, installed capacity has been calculated to assess the relative contributions of the five renewable energy sectors of Bangladesh.

On the distinction between triple gate (TG) and double gate (DG) SOI FinFETs: A proposal of critical top oxide thickness

Distinction between triple gate (TG) and double gate (DG) silicon-on-insulator (SOI) FinFETs is presented here on the basis of their electrostatic and transport characteristics. A study missing in previous works on DG and TG FinFETs is the characterization of these structures with respect to the variation of top oxide thickness. In fact an exact value of the top-oxide thickness that can differentiate DG FinFETs from TG ones has not been reported yet. From this perspective, electrostatic and transport characteristics of DG and TG FinFETs having sub-10 nm fin dimensions are investigated in this work as a function of the top oxide thickness. To duly incorporate the quantum-mechanical (QM) effects in such nanoscale regime of operation, the devices are simulated by self-consistently solving the coupled Schrödingers and Poissons equations. Simulation results suggest that DG and TG FinFETs can be differentiated by a parameter which we define in our work with respect to the surface potentials existing beneath the top and side gates. This finding in effect proposes a critical top oxide thickness of FinFET that can draw the distinction between its DG and TG variants. The results also indicate that deposition of top oxide layer beyond a limit does not bring about any significant change in the electrostatic and transport characteristic of DG FinFETs in the ballistic limit.

Quantum mechanical effect on determining threshold voltage of trigate FinFET using self-consistent analysis

The quantum definition based threshold voltage has been evaluated for triple-gate (TG) SOI FinFETs using self-consistent Schrödinger-Poisson solver. Although a new quantum definition of threshold voltage for multiple gate SOI MOSFETs has been provided in recent literature, in-depth analysis of quantization effects on threshold voltage calculation for highly scaled TG FinFETs is yet to be done. In this paper, the electrostatics of the device has been explored from a quantum mechanical point of view for variation in silicon film thickness in the sub 10nm regime. Also the self-consistent solver, which takes wave function penetration and other quantum mechanical (QM) effects into account, has been utilized here to establish the capacitance-voltage (C-V) characteristics and a modified approach has been proposed for threshold voltage calculation.

Potential future generation nanoscale MOS device: Trigate (TG) or Double Gate (DG) FinFETs?

Performance limit of Tri-Gate (TG) and Double Gate (DG) SOI FinFETs have been compared in terms of ballistic current which is calculated using a modified model shown for conventional MOSFET. Such a simple model for calculating ballistic current in nanoscale multigate MOSFETs is yet to be reported. Comparison of the ballistic current for different Si fin thicknesses reveals that for decreasing fin thickness, strong quantum mechanical confinement degrades the ballistic current. The simulation result presented here contradicts with the previously reported result that TG FinFETs show better performance than DG FinFET and reveals that DG FinFET shows slightly better performance below 5nm fin thickness. This result indicates that in terms of ballistic drive current the tri-gate device is not always favorable than double gate device especially when the device dimension is scaled down deeply.

Self consistent simulation for C-V characterization of sub 10nm Tri-Gate and Double Gate SOI FinFETs incorporating quantum mechanical effects

Capacitance-Voltage (C-V) characteristics of Tri-Gate (TG) and Double Gate (DG) Silicon-on-Insulator (SOI) FinFETs having sub 10nm dimensions are obtained by self consistent method using coupled Schrodinger-Poisson solver taking into account quantum mechanical effects. Though self-consistent simulation to determine current and other short channel effects in these devices have been demonstrated in recent literature, C-V characterization is yet to be done using self-consistent method. We investigate here the C-V characteristics of the devices with the variation of an important process parameter, the silicon film thickness. The gate inversion capacitance should be higher in TG FinFET than that of DG FinFET because of the presence of thick oxide layer under the top gate of DG FinFET. Simulation results validate this phenomenon with an indication that drive current tends to increase with an increase in the number of gates.

Long distance appliance control using mobile Short Messaging Service and internet in parallel

This paper illustrates a secure and reliable system for remotely controlling electrical appliances by Short Messaging Service (SMS) and/or internet. The system requires serial interfacing of two micro-controllers with SIEMENS AX75 cell phone and a personal computer respectively. A microcontroller unit was used to merge the independent subsystems for SMS and internet based control. The micro-controllers were programmed in C and a webpage was created using PHP for internet based controlling. The proposed parallel controlling system incorporates user verification and registration, password protection and RF communication between central controller and the remote receiver segments. The overall scheme offers advantages over so far reported rigid control systems, which involve high cost GSM or GPRS modems. Also the proposed scheme can serve the purpose of appliance controlling in a large scale.

Prospect of charge enhancement by increasing top oxide thickness of silicon-on-insulator fin field effect transistors

The variation of electrostatic and transport characteristics of silicon-on-insulator fin field effect transistors (FinFETs) having sub-10 nm fin dimensions is investigated with the variation of top oxide thickness. Capacitance voltage and ballistic transport characteristics of double gate (DG) and triple gate (TG) FinFETs are obtained by self-consistently solving the coupled Schrodinger’s and Poisson’s equations. Performance enhancement can be obtained in terms of both on-state current and inversion capacitance by increasing the top oxide thickness of highly scaled FinFETs. The work suggests limiting values of the device parameter to differentiate the DG and TG variants of FinFET.

On the performance of BOI, SOI and bulk FinFETs: Impact of BOX length variation

In this paper the Body-Over-Insulator (BOI) FinFET is studied regarding the drain induced barrier lowering (DIBL), self heating effect (SHE) and on-off currents with respect to variation of the length of buried oxide (BOX). Fabrication of this novel type of FinFET, the BOI FinFET, has been reported previously and different characteristics of this structure have been analyzed for a fixed BOX. However the impact of BOX length variation on device performance is yet to be investigated. In this work, the influence of the length of BOX on device performance is investigated by solving 3D self-consistent Schrodinger-Poisson equations in a coupled manner. Simulation results indicate that the length of the BOX, i.e. the degree of insulation of the channel can significantly influence the performance of FinFET. The study has shown that BOI FinFETs stand in between body-tied bulk FinFETs and SOI FinFETs and hence shows the capability of combining the strength of both Bulk and SOI FinFETs.

Role of fin thickness on ballistic transport in nanoscale FinFETs

Performance limit of Tri-Gate (TG) and Double Gate (DG) SOI FinFETs have been compared in terms of ballistic current which is calculated by using a modified model shown for conventional MOSFET. Such a simple model for calculating ballistic current in nanoscale multigate MOSFETs is yet to be reported. Comparison of the ballistic current for different Si fin thicknesses reveals that for decreasing fin thickness, strong quantum mechanical confinement degrades the ballistic current. The simulation result presented here contradicts with the previously reported result that TG FinFETs always show better performance than DG FinFETs and reveals that DG FinFETs show slightly better performance below 5nm fin thickness. This result indicates that in terms of ballistic drive current the tri-gate device is not always favorable than double gate device especially when the device dimension is scaled down deeply.