Apr 24 – 30, 2022
Ettore Majorana Foundation and Centre for Scientific Culture
Europe/Rome timezone

Session

S. Rumyanstev

Apr 25, 2022, 5:30 PM
Ettore Majorana Foundation and Centre for Scientific Culture

Ettore Majorana Foundation and Centre for Scientific Culture

Via Gian Filippo Guarnotti, 26, 91016 Erice TP (Italy)

Description

Abstract:
Although the history of the noise research goes back almost a century, the answers to even fundamental questions are still being discussed. We will review the history and main properties of the 1/f noise in semiconductors, metals, and graphene. We will discuss what causes the1/f fluctuations in these materials and how to compare the noise amplitude in different devices and materials.
It is proved that 1/f noise is caused by the resistance fluctuations. However, the fundamental question of the mobility versus number of carriers fluctuations is still being debated. We will review several proves that the 1/f noise in semiconductors is due to the fluctuations in the number of the charge carriers and look for the materials which might demonstrate the 1/f mobility fluctuations. One of the best candidates for such a material is graphene.
It was shown a while ago that measurements of noise under the condition of geometrical magnetoresistance allow to directly assess the mechanism of low-frequency fluctuations. This kind of experiment already proved that in the majority of cases the 1/f noise in semiconductors is due to the number of carriers fluctuations.
Recent measurements of noise in h-BN encapsulated graphene transistor under the condition of geometrical magnetoresistance prove that the mobility fluctuations are the dominant mechanism of the low frequency noise in high-quality graphene.
The second part of the talk is devoted to the low frequency noise of magnons, which are quanta of the electron spin wave in a crystal lattice. They can be used for information processing, sensing, and other applications. The magnonic device is a rare example of an electronic device based on the electrical insulator.
We will review the experimental results, which show that contrary to the majority of electronic devices the 1/f noise is not found yet in the magnonic devices. The low-frequency noise of magnonic devices is dominated by the generation recombination-like noise with the Lorentzian spectrum and by random telegraph signal noise, in many cases. The presence of the random telegraph signal noise is an indication that just one individual fluctuator causes the noise in a big device with millimeters characteristic dimensions. This is a striking difference with electronic devices where the random telegraph signal noise is usually found in submicron devices.
To conclude, the noise mechanisms are different in different materials and devices, and exaggerating the situation a bit, we can say that there are as many noise mechanisms as there are different electronic systems.

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