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MOSCOW, March 17 Employees of the Moscow Institute of Physics and Technology (MIPT), who studied the properties of a material widely studied in the world — two-layer graphene, have found a way to the possible creation of a new type of electronic devices — high-speed energy-efficient switches, chemical and biological sensors, as well as radiation detectors that could not be created on conventional semiconductors, the Ministry of Science and Higher Education of the Russian Federation reported.
The basis of all modern semiconductor electronics is the so-called p-n junction — the area of u200bu200bcontact between two semiconductors with different types of conductivity. For electrons, such a transition is an energy barrier. The presence of a stepped barrier for electrons in a p-n junction determines its main function in electronics: this junction is one-sided, the current can flow in it only with one polarity of the applied voltage.
In the 1960s, it was discovered that p-n junctions can also conduct current due to the effect of quantum tunneling — «leakage» of electrons under the energy barrier. Similar devices — tunnel diodes — have been used in electronics with low power consumption.
Another important direction in electronics was the increase in the speed of response of electronic devices. Here one cannot do without new materials, where electrons do not encounter obstacles on their way. One of these materials turned out to be two-layer graphene — a two-dimensional modification of carbon formed by two closely spaced layers of graphene.
But the mechanism of current flow in p-n junctions based on two-layer graphene remained misunderstood for a long time. Scientists from the Laboratory of Optoelectronics of Two-Dimensional Materials of the Center for Photonics and Two-Dimensional Materials of the Moscow Institute of Physics and Technology were able to answer this question. In their experiments, they came to the conclusion about the dominant quantum tunneling type of conduction in this material.
“The situation we discovered turns out to be very promising for electronics. Firstly, we have high electronic mobility in graphene, which makes it possible to create fast semiconductor devices. Secondly, we have a tunneling nature of transport, and this makes it possible to control the current at low voltages , that is, energy efficiency. Such a combination of speed and energy efficiency could not be achieved in electronics based on «classical» semiconductor materials,» said Dmitry Svintsov, head of the MIPT Laboratory of Optoelectronics of Two-Dimensional Materials.
According to the authors of the work, the effect they discovered, among other things, is important for the introduction of two-layer graphene into digital electronics: the tunnel effect in two-layer graphene will make it possible to «feel» not only radiation, but also trace amounts of chemical and biological compounds, that is, to act in the role of a sensitive chemical and biological sensor.
This work was supported by grants from the Russian Science Foundation and the Ministry of Education and Science of the Russian Federation. The results of the study were published in the leading specialized international scientific journal Nano Letters.