Page 24 - CFM_Newsletter_CY22

Epitaxial III-nitrides nanostructures for optoelectronic applications

Dr. Sunil S. Kushvaha, CSIR-National Physical Laboratory, New Delhi, November 30 th

Dr. Sunil Singh Kushvaha, Principal Scientist, CSIR-National Physical
Laboratory, Delhi discussed epitaxial III-nitrides nanostructures for optoelectronic
applications. Among various semiconducting materials, III-nitrides (AlN, GaN,
InN, and their alloys) semiconductors stand out as one of the most popular
materials due to their excellent physical and physical and optoelectronic
properties. The speaker discussed about the various GaN nanostructures such
as nanorods, porous NWN, islands and thin films that were grown using laser
assisted molecular bean epitaxy (LMBE) on sapphire-based substrates and
flexible metal foils. Their team fabricated metal-semiconductor-metal (M-S-M) UV
photodetectors on GaN thin film, nano-columns and nanowall networks grown on
GaN sapphire-based substrates. They also conducted the PEC measurement on
GaN NCs on Nb foils under standard conditions showed the effective photo-catalyst nature and observed
an enhancement in PEC efficiency in the case of reduced graphene oxide film coated on GaN NCs. The
speaker concluded the talk by explaining the properties exhibited by hybrid GaN nanostructures which are
suitable for fabricating efficient optoelectronic devices.

Importance of Understanding Ultrafast Reactions in Energy Conversion

Dr. S. Easwaramoorthi, Principal Scientist, Inorganic & Physical Chemistry Laboratory,
CSIR-Central Leather Research Institute, Chennai, December 22
nd
Dr. S. Easwaramoorthi, Principal Scientist, CSIR-Central Leather Research
Institute, Chennai talked about renewable with a negligible carbon footprint. The
process starts with the absorption of light, generation of charge carriers, charge
transport, and consequently, conversion into electricity. The process is similar to
natural photosynthesis and involves different components, from harvesting the
light to converting it to electricity. He emphasized on process efficiency that can
be understood from the ratio of the incident photon to current conversion
efficiency, which is predominantly influenced by several sequential processes,
including light absorption, charge carrier generation, charge injection, charge
recombination, sensitizer regeneration, etc. The time scale of the individual process occurs from the
femtosecond to microsecond/millisecond time scale, thus, unravelling the time scale is essential to develop
new material, and optimizing the device conditions is of paramount importance to realize the device's
potential. His lecture was focused on the nature of the ultrafast events that happen with natural as well as
artificial photosynthetic systems and their evaluation using time-resolved spectroscopic techniques.
Ultrafast transient absorption and time-resolved fluorescence spectroscopic techniques and their
applications in evolving photochemical and photophysical processes in photoinduced reactions, in which
the fundamental charge carrier dynamic processes include interfacial electron transfer, singlet excitons,
triplet excitons, excitons fission, and recombination were discussed.

CFM Newsletter Jan. – Dec. 2022 24 Vol – 2