PhD Defense: "2D Steep Transistor Technology: Overcoming Fundamental Barriers in Low-Power Electronics and Ultra-Sensitive Biosensors"

Deblina Sarkar

July 21st (Tuesday), 3:30pm
Harold Frank Hall (HFH), Rm 4164

photo of deblina sarkar
Aggressive technology scaling as per Moore’s law has resulted in exponential increase in power dissipation levels due to the degradation of device electrostatics as well as the fundamental thermionic limitation in the steepness of turn-on characteristics or subthreshold swing of conventional Field-Effect Transistors (FETs). This dissertation, explores novel two-dimensional (2D) materials (MoS2, WSe2 etc) for obtaining improved electrostatic control and Tunneling-Field-Effect-Transistors (TFETs), employing a fundamentally different carrier transport mechanism in the form band-to-band tunneling (BTBT) for overcoming the fundamental limitations of conventional FETs. This tailoring of both material and device technology can lead to transistors with super steep turn-ON characteristics, which is crucial for obtaining high energy-efficiency and ultra-scalability.

The present dissertation, also establishes, for the first time, that the material and device technology which have evolved, mainly with an aim of power reduction in digital electronics, can revolutionize a completely diverse field of bio/gas-sensor technology. The unique advantages of 2D semiconductors for electrical sensors is demonstrated and it is shown that they lead to femtomolar sensitivity, and also provide an attractive pathway for single molecular detectability- the holy grail for all biosensing research. Moreover, it is theoretically illustrated that steep turn-ON, obtained through novel technology such as BTBT, can result in unprecedented performance improvement compared to that of conventional electrical biosensors, with around 4 orders of magnitude higher sensitivity and 10x lower detection time.

With the aim towards building ultra-scaled low power electronics as well as highly efficient sensors, this dissertation achieves a significant milestone, furnishing the first experimental demonstration of TFETs based on 2D channel material to beat the fundamental limitation in subthreshold swing (SS). This device is the first ever TFET, in a planar architecture to achieve sub-thermionic SS over 4 decades of drain current, a necessary characteristic prescribed by the International Technology Roadmap for Semiconductors and in fact, the only TFET to date, to achieve so, in any architecture and in any material platform, at a low power-supply voltage of 0.1 V. It also represents the world’s thinnest channel sub-thermionic transistor, thus, cracking the long-standing issue of simultaneous dimensional and power supply scalability and hence, can lead to a paradigm shift in information technology as well as healthcare.

About Deblina Sarkar:

Deblina Sarkar received her B. Tech. degree in Electronics Engineering from ISM University, India in 2008 and completed her M.S. at UCSB in 2010. She is currently a PhD candidate at Prof. Kaustav Banerjee’s Nanoelectronics Research Laboratory in the ECE department. Her research, which combines the interdisciplinary fields of engineering, physics and biology, includes development of physics based models for quantum transport, design and fabrication of energy-efficient transistors through tailoring of material and device technology and exploration of unique physical techniques for ultra-sensitive and super-fast detection of biological species.

Ms. Sarkar is the lead author of numerous publications including several high-impact factor journals as well as leading IEEE conferences including IEDM, and has authored/coauthored more than 30 papers till date. Several of her works have appeared in popular press and her research on leveraging the phenomenon of interband tunneling for breaking the fundamental limits of electrical biosensors, has been highlighted by Nature Nanotechnology. She is the recipient of numerous awards and recognitions, including being one of three researchers worldwide to receive the prestigious IEEE EDS PhD Fellowship Award (2011), a "Bright Mind" invited speaker at the KAUST-NSF conference (2015), and one of three winners of the Falling Walls Lab Young Innovator's competition (2015) at UC San Diego. Most recently, she has been selected for the 2015 “Rising Stars in EECS” Workshop hosted by MIT.

Hosted by: Professor Kaustav Banerjee