Nanostructure fabrication inspired by sand dune ripples

What can nanotechnologists learn from ripples on sand dunes?

A lot, smiles Bhaveshkumar Kamaliya, a research scholar with the IITB-Monash Research Academy — who is convinced that if he can mimic the macro-scaled ripples or wave-patterns seen on sand dunes to a nanoscale, it will help him study interactions of ion beams with surfaces of different materials, and perhaps even create self-organized nanostructures.

Nano-scaled structures strongly improve optical, electrical, and magnetic properties of materials. This has led to the study and development of many nanostructure-based devices; however nano-structuring poses a tremendous challenge as the fabrication process for such devices is not available due to limitations of conventional photolithography and electron beam lithography techniques.

“My project has two key aspects,” explains Bhavesh, “(i) experimental investigations for the formation of nanoripples, nanodots, and other complex nanostructures by varying parameters of energetic ion beams, and (ii) molecular dynamics simulations and modelling for understanding, validating and predicting experimental outcomes.”

“The self-organized nanoripples have the potential to serve as functional nanostructures and exhibit novel structures required for photovoltaics, surface plasmons, photonics, bio-sensing, etc.,” says Bhavesh. “Controlling the topography at the nanoscale is challenging and studying the mechanism behind the phenomena could help develop new and complex materials.”

His work is likely to offer the scientific community a systematic understanding of the mechanism behind self-organized nanostructures induced by Focused Ion Beam (FIB) irradiation. It could even lead to the fabrication of an efficient photovoltaic-based energy harvesting device or surface plasmon-based bio-sensing device.

Nanorippled Germanium: (a) Scanning electron micrograph (false coloured) of nanoripples on germanium surface induced by focused ion beam irradiation, (b) mechanism of enhanced light absorption due to multiple reflections through nanoripples and (3) experimentally measured light absorption from nanorippled germanium and bare germanium surface. (Reference: B. Kamaliya, R. Mote, M. Aslam, and J. Fu, APL Materials 6, 036106 (2018); doi: 10.1063/1.5021735).

The Academy is a collaboration between India and Australia that endeavours to strengthen scientific relationships between the two countries. Graduate research scholars like Bhavesh study for a dually-badged PhD from both IIT Bombay and Monash University, spending time at both institutions to enrich their research experience.

Prof Murali Sastry, CEO of the IITB-Monash Research Academy, and a reputed nanomaterial scientist, is excited. “The Academy is an opportunity for industry in Australia and India, as well as for IIT Bombay and Monash University, to train the next generation of rich talent in India. It has the potential to be a significant research institution. Talent from the Academy should become much sought after around the globe. This project could open new avenues on controlling nanoripples orientation and high-efficiency germanium-based photovoltaic applications.”

Indeed. We hope Bhavesh’s work will cause significant ripples — both literal and metaphorical.