Every year ISRO releases vacancies for MTECH NANOTECHNOLOGY. The main area of study and R&D in ISRO for Nanotechnology is in the following sections:

• Synthesis of Nano Materials
• Nano material design
• Nano-Photonics

You will get a lot of scope mainly in the branches of Material Science and optical technology labs.

I hope this answer helps. All the very best for your future endeavors!