'Metal-free' antennas improve interactions between 2D semiconductors and light

AFM antenna image

Scientists at the University of Sheffield have discovered a new way to make 2D materials even more effective when they are used in electronic and optical devices.

The study paves the way for new approaches to the development of photonic devices, such as solar panels and quantum technologies that can process information at incredible speed.

Photonic devices work based on the interaction between light and matter. In the last decade researchers have shown how this interaction can be improved by using 'nanoantennas', which mimic radio antennas to boost the signal of visible light as it interacts with luminescent emitters, such as single molecules or layers of 'two-dimensional' semiconductors that are only a few atoms thick.

As the wavelength of light is significantly shorter than that of radio waves, these nanoantennas need to be much smaller than one millionth of a meter. Typically, researchers have focussed on nanoantennas made of metals such as gold, which cause a lot of light to be lost through the process of absorption.

But a new study, published this week in Nature Communications, has shown how "metal-free" dielectric antennas the light can be used to overcome this problem, paving the way for smaller optoelectronic devices that run more efficiently.

Professor Alexander Tartakovskii from the Department of Physics and Astronomy said: "We placed an atomically thin and ultra-flexible two-dimensional semiconductor on top of small resonant nano-structures made of gallium phosphide, a material suitable for making 'metal-free' nanoantennas. The semiconductor, which is only a few atoms thin, stretches over the antenna pillars and conforms ideally to their shape."

In the study, which was carried out in collaboration with Imperial College London, the Ludwig Maximilian University of Munich and the Technical University of Dortmund, this coupling,  is shown to dramatically improve the interaction between light and the 2D semiconductor.

Professor Tartakovskii said: "These results lead to an enhancement of the overall efficiency of light emission and absorption from atomically thin materials, which could find applications in future electronic and optical devices and quantum technologies.

"This study opens the way to research for compact and efficient photonic devices made with all-dielectric structures interfaced with a vast variety of 2D semiconductors."