Undergraduate Research
Physics of Two dimensional vdW Materials
Twist dependent tuning of excitonic emissions in bilayer WSe2
When two vertically stacked layers are rotated with respect to each other intriguing physics emerges.
However, here, we did not go for small twist angles (therefore, no Moire physics here). Rather, with large twist angles we see a non-intuitive red shift of the higher energy peaks (around K-K exciton peak). These high energy peaks remain unresolved at cryogenic temperatures as they get quenched due to lower lying dark exciton states (not the case with Mo based TMDs).
We try to figure out the reason for such PL shift and indicate the role of interlayer excitons.
Layer parity dependent Raman-active modes and crystal symmetry in ReS2
Several misconceptions prevailing in the literature regarding crystal symmetry, layer-dependent vibrational characteristics, and inter-layer coupling of ReS2 are resolved here.
Layer dependency might not be present due to comparatively weak interlayer coupling, but layer-parity dependency is present in the crystal symmetry confirmed by First-principles calculations (DFT). Excitingly, our experiments and DFT show a clear Raman signature of inversion symmetry breaking in odd-layer (except monolayer) ReS2.
Hybrid Phase Change and Negative Capacitance based FinFET
Ferroelectric Negative Capacitance Assisted Phase-Transition Field Effect Transistor
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 69(2), 863-869 (2022)
Based on our previous work, we further investigate this hybrid device.
Tuning the operating range of each component (NC and PTM) along with proper capacitance matching is necessary. Once this is done, interesting device behavior is seen. Hysteresis, SS, drain-coupling, and differential gain can be precisely controlled at different operating voltage regions.
This hybrid device is capable of working both in logic as well as memory applications.
Design and Analysis of Improved Phase-Transition FinFET Utilizing Negative Capacitance
Introduced a novel hybrid FET design for low-power and high-speed operation.
By simultaneous operation of strongly correlated material, VO2, and ferroelectric material, doped-HfO2, we successfully tune both the body and transport factor of sub-threshold swing (SS). This results in ultra-low SS with much lower off-current and higher on-current compared to baseline FET.