"Novel Photophysics of 2D Materials: Graphene, TMDs and Heterostructures"

Ajay Sood, Professor, Department of Physics, Indian Institute of Science Bangalore, India

February 2nd (Friday), 3:30pm
CNSI 1601

Optoelectronic applications of grapheme and other 2D nanomaterials such as ultrafast detectors, modulators and saturable absorbers demand a deep understanding of photocarrier dynamics on a time scale of a few hundred femtoseconds to tens of picoseconds. In first part of my talk, I will present our recent experimental results on the ultrafast spectral photoresponse of single and bilayer graphene, graphane and few layer transition metal dichalcogenides, as probed by time-resolved optical pump-terahertz probe spectroscopy [1]. The sign and magnitude of dynamic conductivity Δσ(ω) as well as frequency dependence are shown to be very rich in revealing the relaxation dynamics of the photo-excited carriers. Semi-classical generalized Boltzmann transport equation is used to understand Δσ(ω), which requires quantitative evaluation of energy dependent scattering rates. In the second part, I will discuss our recent studies of photo-tunable transfer characteristics in MoTe2-MoS2 vertical p-n heterostructure which show a unique feature as a dip in transconductance near the maximum [2].

[1] S.Kar , V L Nguyen, D R Mohapatra, Y H Lee and A K Sood, ACS Nano (2018)
[2] A K Paul,M Kuiri, D Saha, B Chakraborty, S Mahapatra, A K Sood and A Das, npj 2D Materials and Applications ( June 2017)

About Ajay Sood:

photo of Ajay SoodProf. A.K. Sood, FRS is a Professor in Department of Physics at Indian Institute of Science, Bangalore. He is an honorary Professor in JNCASR, Bangalore. He is currently the President of the Indian National Science Academy and the Secretary General of The World Academy of Sciences (TWAS). He was the President of the Indian Academy of Sciences from 2010 to 2012 and the Vice-President of the Indian National Science Academy. His research interests include Physics of Nano systems and soft matter. He has published more than 390 papers in refereed international journals and holds a few patents.

His work has been recognized by way of many honours and awards .These include the Fellowship of the Royal Society ( FRS) , all the three science academies of India and TWAS ; the civilian honour, Padma Shri by Government of India, S.S. Bhatnagar Prize, G.D. Birla Award, TWAS Prize in Physics, FICCI Prize, Goyal Prize, M.N. Saha Award and Millennium Gold Medal of Indian Science Congress, Sir C.V. Raman Award of UGC, Homi Bhabha Medal of Indian National Science Academy, DAE Raja Ramanna Award of JNCASR, National Award in Nanoscience and Nanotechnology by Government of India, Nano Award by Government of Karnataka, G.M. Modi Award of Science and R D Birla Award for Excellence in Physics by Indian Physics Association. He is one of the Executive Editors of an International journal, Solid State Communications.

Hosted by: Professor Kaustav Banerjee