UrFU Scientists Explore Potoluminescence Exitation of Hexagonal Boron Nitride

15:35, October 27, 2020

Defects in Boron Nitride presuppose its photoluminicence

Impurity defects are responsible for photoluminescence in hexagonal boron nitride (white graphite). This conclusion was made by the staff of NANOTECH Centre of the Ural Federal University. Their assumptions were confirmed by temperature studies of the substance in the range of 7-1100 K (-266 - + 827 ℃). The article, which presents the results of studying impurity complexes with a zero phonon line in the ultraviolet range (4.1 eV), was published in the Journal of Luminescence.

Co-authors: 

• Dr. Alexander Vokhmintsev
• Dr. Ilya Weinstein

“Pure boron nitride works as an emitter in high-wavelength ultraviolet light. But it is impossible to produce absolutely pure material. Impurities are always introduced into the technological process. In our case, it is hexagonal boron nitride with a high content of carbon and oxygen, - says Alexander Vokhmintsev, associate professor of UrFU Department of Physical Techniques and Quality Control Devices. - Impurities create certain defects in the material, which further determines its photoluminescent properties. Our temperature studies have confirmed that impurity defects can form carbon-oxygen complexes and create so-called single-photon emitters. And the excited state of the complex, which is responsible for photoluminescence, is most likely associated with oxygen. "

Single-photon emitters differ from conventional light sources in that they emit light in the form of individual photons with a certain energy, and the time between two successive photons is never less than a certain minimum value. In the case of the samples with which the physicists of Ural Federal University work, the radiation occurs in the ultraviolet range with a wavelength of about 300 nanometers or 4.1 eV. The intensity of the impurity complex luminescence is maximum in the region of 220-260 K (from -53 to -13 ℃), and at a temperature of more than 800 K (527 ℃) the photoluminescence is quenched.

“Currently, scientists pay great attention to methods of directed synthesis, processing and doping of hexagonal boron nitride. The goal is to create promising functional materials that can be used in photonics, nanoelectronics, optoelectronics. In particular, due to the introduction of impurity defects, it is possible to create single-photon emitters that will operate at room temperature,” explains Alexander Vokhmintsev.

It should be noted that a team of scientists from the NANOTECH Centre has been studying the properties of boron nitride for several years. For example, earlier physicists were able to discover that boron nitride also possesses electroluminescence, laser effect, dosimetric properties and kinetics in the nanosecond range.

Hexagonal boron nitride was first used in cosmetics around 1940 in Japan. However, due to the high price, it was soon abandoned. In the late 1990s, the production of boron nitride was optimized, and today it is used by cosmetics manufacturers for make-up bases, eyeshadow, blush, pencils, lipstick.

Due to their high thermal and chemical stability, boron nitride ceramics are used in high-temperature equipment. In addition, boron nitride is found in alloys, resins, plastics, rubbers and other materials. Due to its excellent dielectric and thermal properties, boron nitride is used in electronics as a substrate for semiconductors, windows transparent to microwaves, and a material for seals. Hexagonal boron nitride is also used in xerographic processes and laser printers to seal oxygen sensors.