Research Areas

• Energy Materials and Devices

• Growth, Fabrication and Measurements of optoelectronic Devices

• Oxide heterostructures

• 2-D Van der Waals Materials

Research:

Our main focus on novel functional epi-layers, nanomaterials, nanostructures and devices for optoelectronics and energy applications. We study the electronic structure of ceramics, composite materials, transition metal-oxides, oxide heterostructures and 2-dimensional layered materials by using photoelectron spectroscopy.

Presently, our main scope is on the development of ceramic separators for Li-ion/Li battery. We also study the growth, fabrication and measurements of ultra-sensitive optoelectronic photodetectors.

Recent Research and Development:

Highly resistive GaN/r-GO based photodetector for Harsh Electronics applications:

Broadband ultraviolet photodetector based on hybrid 2D/3D structure was demonstrated. The device employed a highly resistive GaN integrated with thin reduced graphene‐oxide for applications in harsh environments, working up to ±200 V bias and 116 °C with long‐term stability over 28 months without any aging effect. The device operates appreciably in both photovoltaic and photoconductive modes showing high responsivity and fast switching speed. (Advanced Optical Materials 7, 1900340, 2019)

Graphitic-C3N4/Si Binary Multifunctional Photodetector:

A novel binary photoswitching over an ultrabroadband range was demonstrated. The device employs a hybrid 2D/3D structure based on silicon platform which opens up a possibility for the application of graphitic carbon‐nitride (g‐C3N4) nanosheets for light-based binary communications, interconnects for optical computing and weak signal detections. This also significantly improve the performance of silicon solar cells. Covered by online scientific media (Advanced Optical Materials 6, 1800191 2018); highlighted in “Nature India” https://www.natureasia.com/en/nindia/article/10.1038/nindia.2018.76

Self-powered Ultraviolet Photodetector:

Fabrication of high-performance photodetectors using molecular beam epitaxy grown GaN is quite challenging & extremely costly. It is thus very essential to develop simple and cost effective fabrication routes to facilitate their large-scale deployment. This works successfully demonstrated non-cleanroom fabrication of a hybrid device (r-GO/GaN) that works in self-powered mode for ultra-violet detection (Applied Physics Letters 109, 242102, 2016).

Electronic Structure of oxide heterostructures guided by electronic reconstruction revealed by Photoelectron Spectroscopy:

The electronic structure of high quality epitaxial 6 unit cells LaAl1-xCr xO3 (x = 0, 0.2, 0.4, 0.6 and 1.0) on TiO2 terminated SrTiO3 substrates were grown by pulsed laser deposition technique. We have found multiple valence states of both Ti and Cr ions, where an inverse proportionality was observed between the Ti3+ and Cr2+ valence states concentration with increasing x. The progressive increase in the concentration of Cr2+ valence states with the progressive decrease in the concentration of Ti3+ valence states as a function of x and the complete disappearance of Ti3+ states for x ³ 0.6, indicates electronic reconstruction is the most important and universal mechanism for quasi-two-dimensional electron gas in these oxides heterostructures (Physical Review B, 91, 115127, 2015).