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0Specific features of measuring the electrophysical parameters
in polar crystals
V. Umylin1*, N. Kozlova1, E. Zabelina1, V. Petrakov1, A. Temirov1
1- University of Science and Technology MISIS; Leninsky avenue, 4, Moscow, Russia, 119049
* v.umylin@mail.ru
Currently, there is a high demand for devices that use polar cuts of crystals covered with current conductive coatings. Such devices are compact and highly reliable, but their service life is limited. In particular, due to the processes of degradation and aging of the surfaces of crystalline elements upon contact with conductive coatings.
Degradation is usually associated with external influences that lead to a significant negative change in the required properties. Aging is considered as a spontaneous change in electromechanical properties with time without the application of external stress and at a constant temperature. Therefore, aging and degradation lead to unreliability of the readings transmitted by devices and a reduction in their service life.
It is known that a conductive coating can greatly influence to the electrical and dielectric properties and even the phase stability of the material. This leads to degradation and aging of the surfaces of crystalline elements. Typically, consideration of the contribution of conductive coatings to the effects of fatigue and aging is usually limited to the processes of delamination of conductive coatings, as well as changes in their microstructure or geometric parameters. However, other phenomena are also observed.
The purpose of this work was to study the features of measuring electrophysical parameters in samples of polar cuts of a-LiIO3 crystals with different conductive coatings materials and using various measurement schemes.
The samples of a-LiIO3 polar cut (perpendicular to the 6th order inversion axis) without preliminary polarization and external influences with different conductive coating materials (In, Al, Ar, Cu, Cr) were used for research. Samples with symmetrical conductive coatings were studied Ei|crystal|Ei. Samples with different conductive coatings were also studied according to the following principle: Ei|+crystal-E then E2|+crystal-|Ei. Investigation of samples with the above-mentioned conductive coatings were carried out in the temperature range 25-210°C. To set and maintain a certain temperature regime, a heating chamber, a temperature control system and a heater power supply were used. The furnace temperature was recorded using a chromel-alumel thermocouple.
The temperature dependences of the short-circuit currents of the samples were obtained. The influence of the material of conductive coatings and the side of application of the electrodes on the value of the short-circuit currents and the direction of their flow has been established.
Studies of the electrophysical parameters in polar crystals were carried out in the accredited laboratory of semiconductor materials and dielectrics "Single crystals and stock on their base" NUST MISIS with financial support from the Ministry of Education and Science of Russia within the framework of the state assignment to universities FSME-2023-0003.
