Subhananda Chakrabarti

INFRARED PHOTONIC DEVICES GROUP

Department of Electrical Engineering, IIT Bombay

About

Prof. Subhananda Chakrabarti has been involved in research in the field of advanced optoelectronics both in the infrared and in the ultra-violet domain. The research involves carefully analyzing the device physics, coupled with theoretical modelling and followed by extensive experimental optimization. His experimental research involves all the steps starting with growth of device heterostructures (using complex systems like Molecular Beam Epitaxy), followed by fabrication of working devices using state-of-art techniques, and finally characterization and testing of the same.

Prof. Chakrabarti has made contribution to research on Quantum Dot Infrared Photodetectors (QDIPs), to establish such devices as viable third-generation imaging technology fall outs for the IR community worldwide. The research led to some key breakthroughs. For instance, Prof. Chakrabarti was the first to demonstrate state-of-art characteristics of quaternary-capped QDIPs, which surpassed all previous world records in terms of a combination of very high responsivity with detectivity (needed for high resolution night vision devices). He has demonstrated multicolour, broadband, quaternary-capped InAs/GaAs QDIPs having ultra-narrow line-widths never seen before (needed for hyperspectral imaging applications). He is also the first one to demonstrate that ex-situ ion implantation in QDIPs drastically enhances their signal-to-noise ratio. His demonstration of strain-coupling to enhance the performance characteristics in QDIPs would surely open up new venues of research in QD research. Finally, his research on better optical and spectral enhancement of InAs/GaAs QD materials and devices using Au-Ge plasmonic nanoparticles outmatched those earlier reported for Au plasmonic nanoparticles.

In particular, Prof. Subhananda Chakrabarti’s research in the infrared domain has provided strong impetus to the indigenous development of infrared (IR) cameras for night vision and surveillance applications. Prof. Chakrabarti played a central role in the establishment of the advanced III-V compound (GaAs and GaSb) semiconductor laboratory at IIT Bombay. The facility is aimed at spearheading the indigenous development of nanotechnology-based thermal imaging cameras, in keeping with Prof. Chakrabarti’s vision of indigenization.

Prof. Chakrabarti’s group demonstrated India’s first high-temperature operating GaAs-based thermal imaging devices/sensors, responding at long wavelengths (> 8 µm) capable of detecting human objects. The first InGaAs-capped and dot-in-a-well (DWELL) QDIPs developed in India, which demonstrate state-of-the-art detectivity (signal-to-noise ratio) values, merit special mention. These innovations enabled Prof. Chakrabarti to develop prototypes of the 320×256 QDIP Focal Plane Arrays, which lies at the heart of thermal camera, for the first time in the country.

In the ultra-violet (UV) domain, Prof.Chakrabarti took up the challenging research of demonstrating stable p-type doping in ZnO (proposed to be a better alternative to the existing commercial Gallium Nitride (GaN) technology). His demonstration of very stable p-type doping of ZnO and ZnMgO via PIII (Plasma Immersion Ion Implantation) doped phosphorous and nitrogen have not been reported earlier and, may be considered as a breakthrough in realizing viable ZnO based light emitting diodes (LED) and lasers. This research, in fact, culminated in the demonstration of homojunction UV LED, the report of which is indeed a rarity in ZnO-based research internationally. This would also open possibilities of future expansion of ZnO-based optoelectronics.

During the last 12-13 years, 17 (Seventeen) of Prof. Chakrabarti’s PhD students have graduated. Prof. Chakrabarti have also extensively promoted undergraduate research at IIT Bombay and more than 20 (twenty) international journal papers have been published, where the undergraduate student is either the first or a coauthor.

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