NSU Scientists Researching the 6G Range

Scientists at the Laboratory of Functional Diagnostics of Low-Dimensional Structures for Nanoelectronics at the NSU Analytical Technology Research Center are exploring the possibility of using gallium selenide in devices for quickly receiving, storing, and transmitting large amounts of data in the 6G range.

Laboratory researcher Olesya Shevchenko talked about their work,

The terahertz range is the range of the future, but it presents some challenges. Silicon electronics, that are suitable for all previous generations of data transmission devices, are not suitable for these frequencies. In this range we need to work at frequencies where silicon becomes less transparent and loses other necessary properties. Therefore, scientists around the world are faced with an important question, how do you replace silicon that has been used so effectively for a long time? Today, I am searching for materials that can, by passing light or electrical charges through their medium, transmit a large amount of data with less interference and have a high efficiency. For example, if silicon produces 25% efficiency in the terahertz range, the scientists’ task is to find one that will produce at least 90% and, ideally, 100%.

Shevchenko is currently experimenting with gallium selenide and sulfur, which is used as a dopant,

Gallium selenide in its pure form is a very soft material, reminiscent of plasticine. But if you add sulfur to it, it becomes harder. Then it is easier to use it, for example inserting it into the design of a microcircuit. Gallium selenide has many useful properties because despite its softness, it is durable in the required ranges. It also has a high laser breakdown threshold and birefringence coefficient, which is very important for certain tasks. If you add too much sulfur, it will become solid and lose some other important properties we need. Specifically, it will lose its nonlinear properties that are necessary for operation at 6G frequencies when interacting with laser radiation with a 1.5-micron wavelength of optical communication. Our task was to find out what amount of this substance, when adding it to the main gallium selenide crystal, will achieve the optimal balance of characteristics. I think we succeeded.

Shevchenko conducts her research on a terahertz spectrometer, which she assembled using a terahertz radiation generator she also developed based on “metal – dielectric – semiconductor”. This work is financed thanks to her winning the “UMNIK – Photonics” competition in 2020. Her device had the best characteristics and was patented.

The researcher explained,

It is difficult to determine what percentage of data gallium selenide transmits because there are no 6G devices. We are inclined to believe that this figure may be comparable to the conductivity of silicon in 5G devices (100%), but we cannot make such a definitive statement. We can say for sure that it is generally possible to use gallium selenide in 6G devices, but whether it is an ideal material for these purposes is an open question. Scientists all over the world are conducting similar research on various materials. It is possible that one of them will be able to discover a more suitable material or, maybe, the gallium selenide we are studying will turn out to be optimal.

Author: Elena Panfilo, NSU Press Service