Exitonites – electrically neutral quasiparticles – have extraordinary properties. They exist only in semiconducting and insulating materials and can easily be readily available in two-dimensional (2D) materials of just a few thick atoms such as carbon and molybdenite. When these 2D materials are combined, they exhibit quantum properties that no material has on its own.
The new study by Tel Aviv University explores the generation and spread of excitons in 2D materials in an unprecedentedly small time frame and with extremely high spatial resolution. The research was conducted by Professor Chaim Sukhovsky and Dr. Michael Mredagen from TAU Raymond & Beverly Sackler Faculty of Science and published in Scientific Advances on February 1
Quantum mechanics is a fundamental theory in physics that describes nature on the smallest scale of energy. "Our new visualization technology captures the motion of excitons in a short time and nanometer scale," says Dr. Mrejen. "This tool can be extremely useful in looking at the reaction of the material at the first moments when the light has affected it."
"Such materials can be used to significantly slow down the light in order to manipulate or even store it, which is very needed after communications and quantum computers based on photonics," says Professor Sukhovsky. view of the possibilities of the tool, this excursion opens new opportunities for visualization and manipulation of the super-fast response of many other material systems in other modes of the spectrum, such as the average infrared range in which many molecules vibrate.
Scientists developed a unique technique of spatial-temporal visualization on a femtosecond-nanometer scale and observed the dynamics of exciton-polariton in tungsten dichlenide, semiconductor material, at room temperature
The exciton-polariton is a quantum creature generated by the combination of light and matter.Through the investigated specific material, the rate of propagation was about 1% of the speed of light.In this period of time the light manages to pass only a few hundred nanometers.
"We knew that we possess a unique tool for characterizing the characteristics and that these 2D materials are good candidates for studying the interesting behavior on ultra high-speed crossroads," says Dr. Mrejen. It should be added that the material, tungsten diselenide, is extremely interesting in terms of applications, it supports such lightweight substances in states of very limited size, up to the thickness of one atom, at room temperature and in the visible spectral range.
Researchers are now studying methods for controlling the speed of semiconductor waves, for example, by combining several 2D materials into stacks.
Excitons pave the way to highly effective electronics
M. Mrejen et al., Transit dynamics of the exciton-polariton in WSe2 by means of super-fast visualization of the near field, Scientific achievements (2019). DOI: 10.1126 / sciadv.aat9618