Studying, Learning, Teaching, & Research Interests

Energy-Efficient Integrated Circuits, Adaptive Integrated Circuits (ICs) and IC sensors, Low Power Mixed-Signal ICs for a variety of applications, Neuromorphic VLSI design, Constrained Optimization Circuits, Beyond-CMOS devices, and Three-dimensional (3D) Integrated Circuits.

The observation by Gordon Moore in 1965 (now universally referred to as Moore’s law) that the number of transistors on an integrated circuit would double every couple of years has become a beacon that continues to drive the electronics industry. Integrated circuits have grown exponentially from the 30-transistor devices of 1965 to today’s high-end microprocessors exceeding 500 million transistors integrated on a silicon chip the size of your fingernail. Moore’s law will continue, with over one billion transistors per chip expected by 2010. Decades of research and 

manufacturing investment to drive Moore’s law has resulted in significant performance gains while simultaneously bringing about significant cost reductions. As an example, in 1968 the cost of a transistor was around one dollar. By 1995, one dollar bought about 3000 transistors. Today, one dollar purchases about five million transistors.

The Internet explosion has changed how we go about our everyday lives. The thirst for information and the need to ‘always be connected’ is spawning a new era of communications. This new era will continue to spur the need for higher bandwidth technologies to keep pace with processor performance. Because of Moore’s law, computing today is limited less by the computer’s performance than by the rate at which data can travel between the processor and the outside world. Fiber-optic solutions are replacing copper-based solutions, which can no longer meet the bandwidth and distance requirements needed for worldwide data communications.

Over the last decade, optical communication technologies have migrated steadily from long-haul backbones to the network edge, invading metropolitan area networks (MANs) and campus-level local area networks (LANs). A key inflection point will come with the ability to economically connect central offices to diverse network access points. One of the most important consequences of this migration has been the need to develop more efficient and lower cost optical solutions. The future of optical networking rests on the ability to bring optical technology from the MAN or LAN, into the data center, to the curb, to the home and, if possible, maybe some day directly to the microprocessor. Today, optical devices are large, bulky and mostly not fabricated from silicon. Most optical components are made from III – V-based compounds such as indium phosphide (InP), gallium arsenide (GaAs) or the electro-optic crystal lithium niobate (LiNbO₃). These optical devices are often custom-made and assembled from discrete components. They typically are assembled by hand with very little automation. We are just now beginning to see some standardization occurring in the optical arena. The net result of all this is that these optical devices are relatively expensive. Optical technology to the mass market may happen only if one can bring data-com economics, high-volume manufacturing and assembly to the optical world.

This raises several questions. Can we ‘siliconize’ photonics? Can we call on the decades of research and manufacturing experience gained from the microelectronics industry and apply it to photonics? Could silicon be used as an alternative to more exotic materials (such as InP or LiNbO₃) 

typi- cally used to produce optical devices? Could one monolithically integrate multiple photonic circuits on a single silicon chip to increase performance while simultaneously reducing cost? Could one implement standardiza- tion and high-volume manufacturing techniques to reduce cost? Could we combine electronics with photonics to bring new levels of integration, and possibly a derivative form of Moore’s law to photonics?

These are very good questions. Although it is well known that silicon is the optimal material for electronics, only recently has silicon been considered as a practical option for optics. Silicon in fact has many properties conducive to fiber optics. The band gap of silicon ( 1.1 eV) is such that the material is transparent to wavelengths commonly used for optical transport (around 1.3– 1.6 µm). One can use standard CMOS- processing techniques to sculpt optical waveguides onto the silicon surface. Similar to an optical fiber, these optical waveguides can be used to confine and direct light as it passes through the silicon.

Due to the wavelengths typically used for optical transport and silicon’s high index of refraction, the feature sizes needed for processing these silicon waveguides are on the order of 0.5– 1 µm. The lithography requirements needed to process waveguides with these sizes exist today. If we push forward to leading-edge research currently underway in the area of photonic band-gap devices (PBGs), today’s state-of-the-art 90-nm fabrication facilities should meet the technical requirements needed for processing PBGs. What this says is that we may already have all or most of 

the processing technologies needed to produce silicon-based photonic devices for the next decade.In addition, the same carriers used for the basic functionality of the transistor (i.e. electrons and holes) can be used to modulate the phase of light passing through silicon waveguides and thus 

produce ‘active’ rather than passive photonic devices. Finally, if all this remains CMOS-compatible, it could be possible to process transistors alongside photonic devices, the combination of which could bring new levels of performance, functionality, power and size reduction, all at a lower cost. So the answer is, yes, it is possible to ‘siliconize’ photonics. Will it happen? The Internet growth engine is alive and well and the optical communications industry will need to move from custom low-volume technologies to high-volume, standardized building blocks. This may happen only if silicon is the material on which we build this photonic technology in the future.

We are on the cusp of revolutionary changes in communication and microsystems technology through the marriage of photonics and electronics on a single platform. By marrying large-scale photonic integration with large-scale electronic integration, wholly new types of systems-on-chip will emerge over the next few years. Electronic-photonic circuits will play a ubiquitous role globally, impacting such areas as high-speed communications for mobile devices (smartphones, tablets), optical communications within computers and within data centres, sensor systems, and medical applications. In particular, we can expect the earliest impacts to emerge in telecommunications, data centers, and high-performance computing, with the technology eventually migrating into higher-volume, shorter-reach consumer applications. In the emerging field of electronics in the 1970s, Lynn Conway at Xerox PARC and Professor Carver Mead at Caltech developed an electronics design methodology, wrote a textbook, taught students how to design electronic integrated circuits, and had their designs fabricated by Intel and HP as multi-project wafers, where several dif- ferent designs were shared in a single manufacturing run. These efforts led to the foundation of an organization named MOSIS in 1981 that introduced cost sharing of fabrication runs with public access. The inexpensive design-build-test cycle enabled by MOSIS trained, and continues to train, thousands of designers who are responsible for the ubiquity of electronics we see today. MOSIS got started based on commercial processes that were already in production, and opened them up to the design community for prototyping and research purposes.

One of the keys to the long-term success of the microelectronics community, and in particular of the CMOS community, has been this type of access. By making these volume production processes publicly available for research and development at modest cost, anyone with a very modest level of funding is able to do cutting edge, creative work in a process that can instantly go into large-scale production. Training student engineers to use the production tools and processes, and then letting them loose to build cutting-edge circuits which can, with modest funding, be translated into fabless IC start- ups, has been the source of countless successful companies. It is hard to over-emphasize the difference between this and the situation in photonics (and most engineering fields), where getting from research into production involves huge barriers. Silicon photonics is currently at the same early stage of expansion as electronics was in the 1970s, but with a major advantage for chip fabrication: existing silicon foundries

Computational Simulation and Research on Magnetic Tunnel Junction (MTJ), Topological Insulators, Spin-Orbit Torque (SOT) and SOT Switching, and Spin-Transfer Torque Magnetic Random Access Memory (STT-MRAM).

Computational Simulation and Research on Magnetic Tunnel Junction (MTJ), Topological Insulators, Spin-Orbit Torque (SOT) and SOT Switching, and Spin-Transfer Torque Magnetic Random Access Memory (STT-MRAM).

Approximately for one and a half years, from my own interest on Spintronic Devices, I alone, without any advisor, supervisor, researcher guidance, or any help from the faculty members, managed to learn the Spintronic Materials Modeling & Simulation with DFT • DFT+U+V on Quantum ESPRESSO and other auxiliary tools such as: BURAI, VESTA, XCrySDen etc.

During the beginning of my 1st Year 2nd Semester undergraduate career, I started to learn and perform small tasks, on Spintronic Material Modelling and Simulation based on the First Principle Study calculation based on Density Functional Theory (DFT) and DFPT, DFT+U, and others, till, 2nd Year 1st Semester of my undergraduate career in BSc (Engg.) in EEE.

My primary focus was suitable material selection for Spintronic application and characteristic investigation of the materialistic properties, through developing a novel Transition Metal Dichalcogenide (TMD), or Transition Metal Oxides (TMO), or MXene, and by the First Principle Study calculation based on Density Functional Theory (DFT).