Research

Research Interests

• Modeling, simulation, fabrication and characterization of state-of-the-art solid state semiconductor devices

• Simulation and characterization of photovoltaic devices

• Exploration of novel material properties from first principle atomistic simulation

Supervisor(s)

• Dr. Quazi Deen Mohd Khosru, Professor, Dept. of EEE, BUET [Website]

Research Experience

1. Gate Capacitance and Drain Current Modeling of InGaAs Gate All Around MOSFET

As traditional bulk MOSFET has reached physical scaling limit, intensive research is going on to find alternative device architecture that will allow the continuation of the scaling trend without degradation of device performance. Gate all around (GAA) device structure has demonstrated great potential due to strong immunity to short channel related issues that significantly degrade performance of deep sub micron devices. Besides looking for alternative device architecture, research is also going on to leverage the superior electronic properties of III-V materials such as InGaAs in the channel region of ultra scaled device. To analyze the prospect and evaluate its performance metrics, we have developed a rigorous analytical model for gate capacitance and drain current of InGaAs GAA MOSFET. Publications: Superlattices and Microstructures (Under review), Journal of Computation Electronics (Under review)

2. Analytical Investigation of Electrostatic and Transport Phenomena of GaN Nanowire Junctionless MOSFET

As the traditional bulk MOSFET has reached physical scaling limit, further miniaturization of this device has become extremely challenging. Junctionless Nanowire MOSFET has recently emerged as a viable candidate to continue the scaling trend for future technology node. Due to its superior electronic properties compared to Si, GaN has shown great potential to replace Si as channel material in ultra scaled device. The aim of this research is to develop a comprehensive analytical model for electrostatics and transport characteristics of GaN Nanowire Junctionless MOSFET. In this work we have solved quasi 2-D Poisson equation in radial coordinate using regional approximation and formulated an analytical model for gate capacitance of this device and analyzed the capacitance-voltage characteristics for different device physical parameters including doping concentration, nanowire radius and oxide thickness. Furthermore, we have proposed a robust drain current model incorporating short channel effect and other non ideal effects such as velocity saturation, mobility degradation, channel length modulation, parasitic contact resistance and schottky barrier height in source/drain contact and investigated the transport properties and short channel performance metrics such as subthreshold slope (SS), drain induced barrier lowering (DIBL), threshold voltage roll-off of this device for various device physical parameter such as nanowire radius, oxide thickness, channel length, doping concentration. The proposed model will act as guideline for extensive investigation and optimization of GaN nanowire junctionless MOSFET for future technology node. Publications: IEEE Transactions on Electron Devices 2020, IEEE-NANO 2020

3. Analytical Modeling of Electrostatic and Transport Properties of Enhancement Mode GaN Double Channel HEMT

GaN based High Electron Mobility Transistor (HEMT) has attracted many researchers due to its superior performance driven by the polarization induced high density and high mobility 2-D electron gas (2DEG) at the AlGaN/GaN heterointerface. Recently Double Channel GaN HEMT has been demonstrated with superior transport properties. To understand the full potential of DC-MOS-HEMT, analytical modeling of the device providing physical insights of the operating mechanism and serving as a guideline for device design is of great value. In this work we have developed comprehensive analytical model of electrostatic and transport phenomena of GaN double channel HEMT taking into account the coupling between lower and upper channel, velocity saturation of electrons in 2DEG, the spontaneous and piezoelectric polarization at the heterointerface, field dependent mobility and parasitic resistance in source/drain contact. Publications: IEEE Transactions on Electron Devices 2019

4. Quantum Mechanical Simulation of Capacitance-Voltage Characteristics of Enhancement Mode GaN Double Channel HEMT

The High Electron Mobility Transistor (HEMT) is a novel solid state device which widely used in high power application. Recently GaN HEMT has gained reasonable interest in the research community due to polarization induced high density and high mobility 2-D electron gas (2DEG) at the hetero interface which significantly enhances device performance. Quantum mechanical effect plays a significant role in the operation of this device. The self consistent solution of Schrodinger-Poisson equation is a popular technique to investigate the device performance incorporating quantum mechanical effect. In this work the self consistent method has bee utilized to investigate capacitance-voltage characteristics of Enhancement mode GaN double channel HEMT. Publications: IEEE NMDC 2018