Gallium nitride (GaN), a common material for blue light emission, is one of the most advanced semiconductors – useful for light-emitting diodes, power electronics and optoelectronic applications. Extending the optical resonance of GaN from visible to mid- and far-infrared spectral ranges will enable new applications in many emerging technologies.

GaN nanostructures can be used to constrain and absorb IR light, creating highly effective IR absorbers, emitters and modulators for imaging, sensing, energy production and other applications.

The emission and absorption of infrared light with GaN nanostructures has been demonstrated for the first time by scientists at the Jawaharlal Nehru Center for Advanced Scientific Research (JNCASR), an independent institute of the Department of Science and Technology in Bengaluru.

This is the first time that infrared light-matter interactions have been observed in GaN, despite the fact that GaN’s blue light emission has long been known and used in LEDs. For this demonstration, they used a scientific phenomenon known as surface polariton excitations in GaN nanostructures, which result in light-matter interactions in the IR spectral range.

Surface polaritons are certain electromagnetic wave modes when a conductor and an insulator, such as air, come into contact. They can also induce plasmon polaritons in GaN by altering the morphology and shape of the nanostructures, extending the interaction between light and matter to other parts of the electromagnetic spectrum. These polaritons are quasiparticles with properties similar to those of light and matter.

The scientists used an advanced material deposition tool called molecular beam epitaxy at the International Center for Materials Science in JNCASR to create these GaN nanostructures. This device grows nanostructures of high-quality material with dimensions about 100,000 times smaller than the width of a human hair using ultra-high vacuum, which corresponds to the conditions in space.

The development of polariton-based electronics, which has several advantages over traditional electronic devices, is enabled by such advanced materials. Applications for polaritonic technology include:

Dr. Bivas Saha, assistant professor at the Jawaharlal Nehru Center for Advanced Scientific Research, said: “Over the past 25 years, blue LED with GaN has changed our world significantly. While GaN’s blue light emission is well understood, the use of GaN for infrared optics is not well established. Our work demonstrates a new path for using GaN in infrared nanophotonic applications. Importantly, the scientists said the polariton excitations from the infrared surface that we demonstrated could also be translated to many other semiconductors.

“This work will greatly benefit in addressing the demand for IR sources and detectors for energy, security, imaging and other applications.”

Magazine reference:

  1. Krishma Chand Maurya, Abhijit Chatterjee, Sonnada Math Shivaprasad and Bisvas Saha. Morphology-controlled Reststrahlen Band and Infrared Plasmon Polariton in GaN Nanostructures. Nano letters. DOI: 10.1021/acs.nanolett.2c03748