GUWAHATI: Researchers from the Indian Institute of Technology-Guwahati (IIT-Guwahati) and USA’s Columbia University have developed a ground-breaking method for nano-patterning using a simple table top infrared (IR) laser.
Nano-patterning involves creating patterns on materials at the nano-meter scale, which is a hundred thousand times smaller than the width of a single human hair.
This technique enables the fabrication of nano-scaled optical elements and polariton cavity, crucial for devices such as advanced light detectors, solar cells, lasers and light-emitting diodes (LEDs).
Traditional nanoscale patterning methods require specialised equipment and infrastructure, such as clean rooms for electron beam lithography machines, or techniques involving high local heating and plasma due to the direct writing.
In search of a more accessible and cost-effective alternative, the multi-institutional team adopted a less strenuous process called ‘optical driving,’ leveraging the resonance frequency principle in materials.
By employing this technique, termed ‘unzipping,’ the researchers were able to cleave hexagonal boron nitride using an IR laser, which resulted in the formation of atomically sharp lines across the sample, measuring just a few nano-meters in width.
Laser wavelengths at 7.3 micrometers facilitated clean lattice breaks, yielding controllable nanostructures.
Subsequently, the scientists ‘unzipped’ two parallel lines, creating a nano-dimensional cavity capable of trapping phonon-polaritons, unique quasi-particles formed from the interaction of light and vibrations.
These trapped particles have the potential to concentrate light into sub-nanometric spots, which could be beneficial for highly sensitive mid-infrared sensing and spectroscopy.
Emphasising the significance of this breakthrough, Assistant Professor of the Department of Physics at IITG, Rishi Maiti, said, “This novel nano-patterning technique using optically induced strain opens doors to a myriad of possibilities in nanoscience and technology. Its simplicity and effectiveness mark a significant advancement in the field, with far-reaching implications across various industries.”
Prof Maiti envisions diverse applications for this breakthrough, including designing hard masks for electrode fabrication on two-dimensional (2D) materials and forming twisted heterostructures (a semiconductor structure in which the chemical composition changes with position) for quantum technologies.