Monday, September 5, 2022

Scientists Found Luminescence in Unique Dielectric Material

Hafnium dioxide was studied in the Ural Federal University Research Center Nanomaterials and Nanotechnologies.
Photo credit: Ilya Safarov

Scientists from the UrFU studied the luminescent properties of hafnium dioxide, a material with high dielectric permittivity. This compound is used in the micro- and nanoelectronics industry. Physicists found that due to the presence of exotic quasiparticles in their electronic structure, the compound exhibits intense luminescence at extremely low temperatures. The discovery will help in the creation of future electronic devices, such as lasers, optical sensors, or biomedical sensors. The results are presented in the Journal of Luminescence.

"We studied the temperature effect on the luminescence properties of the nanostructured hafnium dioxide powder. When we cooled the compound to 40 K (-233°C), we recorded ultraviolet luminescence in the compound, which became brighter as the sample cooled. We were able to build a model that describes at what point in the compound additional luminescence is formed, how the intensity of the luminescence changes and is characterized. This model can be useful in the development of highly sensitive sensors in modern optoelectronic devices or compact biosensors for visualization of various processes," notes Artyom Shilov, Junior Researcher at the Nanotech Research Center at UrFU Ural Interregional Research and Scientific Center.

Scientists determined that this luminescence results from the decay of an autolocalized exciton, an exotic quasiparticle consisting of an electron and a hole bound together by the force of electrostatic attraction. Temperature intensifies the interaction of the exciton with the oxygen atoms in the compound structure, and the optical properties of the entire compound change because of this.

"The efficiency of practical application of hafnium dioxide largely depends on various kinds of defects, including oxygen vacancies in its structure. In the development of next-generation nanoelectronics elements, these structural defects can also play a positive role, changing the material's characteristics in the right direction. "We found that, due to the peculiarities of hafnium dioxide, the exciton is "bound" to a certain position in the crystal lattice, and this results in luminescence enhancement," adds Artyom Shilov.

Hafnium dioxide is a promising material for nanoelectronics. For instance, for a new generation of computer processors with higher performance and smaller chips. Hafnium dioxide is also a promising basis for memory cells, which will run an order of magnitude faster than today's flash drives or solid-state drives. Scientists emphasize that a thorough study of the exciton effects discussed may contribute to the improvement of memory memristive cells.

The study was conducted by scientists at the Ural Federal University's Nanocenter and the Rzhanov Institute of Semiconductor Physics Siberian Branch of Russian Academy of Sciences with the support of the Ministry of Science and Education of the Russian Federation (project FEUZ-2020-0059). They used pure hafnium dioxide in powder form for the study. Now the researchers are figuring out how the properties of the compound are affected by the change in shape. They replaced the powdered material with nanotubes and have already found some differences in the properties of the compound.

Source/Credit: Ural Federal University