Research in Detail

We investigate electronic transport in crystalline and amorphous oxide semiconductors, such as WO₃, W-doped InO, etc. We utilize various methods such as Hall measurements, cryogenic measurements, and low-temperature characterization, combining these with numerical and analytical modeling to characterize and understand fundamental electronic transport mechanisms.

Additionally, we develop thin film transistors (TFTs) using these materials for various applications.

Key focus area:

Technology scaling has driven the development of semiconductor technology. However, efforts to continue scaling have met numerous challenges, both from engineering limitations and the fundamental limits of silicon. Two-dimensional (2-D) materials are a potential candidate for highly scaled nodes due to their atomically thin nature and excellent electrostatics.

My research in 2D electronics encompasses various aspects, including contact and gate stack engineering, steep subthreshold slopes FETs, and ultra-scaled short-channel FETs.

Two-dimensional (2-D) materials show promise for highly scaled nodes because of their atomically thin composition and exceptional electrostatic properties. The remarkable surface-to-volume ratio and sensitivity to external factors also make 2-D materials ideal for bio-sensing applications. By appropriately functionalizing field-effect transistor (FET) technology, ion-sensitive FETs (ISFETs) can be created for detection of pH and various biomolecules.

Despite the advantages of CMOS platforms, ISFETs suffer from major bottlenecks, which includes limited sensitivity (< 59 mV/pH, the Nernst limit), need for isolation, and challenges in reliability due to problems like drift. In our lab, we investigate device architectures and innovations to surpass these challenges. The Nernst limit must be surpassed to achieve higher resolution measurements of pH and biomolecules. Through a heterostructure of WSe₂ and MoS₂, we have demonstrated super-Nernstian pH sensitivity, reaching 346 mV/pH. This device capitalizes on the charge screening effect of the interface and inversion charges at the heterointerface for enhanced sensitivity. Additionally, we've utilized a TCAD-based approach, integrating ferroelectric negative capacitance effect onto the WSe₂/MoS₂ heterostructure device, and demonstrated sensitivities reaching 4.38 V/pH.

Key focus area:

My "Beyond Moore" research explores novel physical effects to overcome the fundamental limits of classical computing. This includes exploring filamentary devices showing memristive and threshold switching activity. I also explore switching activity in various material systems including gate stack engineered MoS₂-HfO₂ and hBN systems.

I use high-speed electrical measurements to study these emerging devices with eventual applications targeting both conventional and emerging Neuromorphic computing platforms.

TCAD simulation is used whenever necessary, providing deep insights into device physics that are often inaccessible through experimental characterization alone. I utilize industry-standard tools like Silvaco ATLAS, Sentaurus TCAD, and Ginestra to model FETs, ISFETs, gate stacks, and complex heterostructures.

Non-standard functions can be realized by integrating user-defined material models for 2-D materials, emulating electrolyte interactions, and combining with numerical models in Matlab/Python. This helps in predicting device behavior, understanding physical mechanisms, and optimizing device architecture. This synergy between simulation and experimental nanofabrication significantly accelerates the development cycle for next-generation nano-electronic devices.