Browsing by Author "Perevalov, T. V."

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Charge transport in amorphous Hf0.5Zr0.5O2
(2015-03-09)
Islamov, D. R.
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Perevalov, T. V.
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Gritsenko, V. A.
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Cheng, C. H.
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Chin, A.
In this study, we demonstrated experimentally and theoretically that the charge transport mechanism in amorphous Hf0.5Zr0.5O2 is phonon-assisted tunneling between traps like in HfO2 and ZrO2. The thermal trap energy of 1.25 eV and optical trap energy of 2.5 eV in Hf0.5Zr0.5O2 were determined based on comparison of experimental data on transport with different theories of charge transfer in dielectrics. A hypothesis that oxygen vacancies are responsible for the charge transport in Hf0.5Zr0.5O2 was discussed. (C) 2015 AIP Publishing LLC.
Mechanism of GeO2 resistive switching based on the multi-phonon assisted tunneling between traps
(2012-06-11)
Shaposhnikov, A. V.
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Perevalov, T. V.
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Gritsenko, V. A.
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Cheng, C. H.
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Chin, A.
Model of evenly distributed traps in bulk dielectric is proposed for the resistive memory switching mechanism. Switching from high resistance to the low resistance state is explained by several-fold increase in trap concentration after the application of switching voltage. Both high and low resistance conductivities are governed by multi-phonon ionization and tunneling between neighboring traps. Thermal trap energy for oxygen vacancy and electron effective mass for crystal alpha-GeO2 were calculated using density functional theory and used for the fitting of our charge transport model of resistive memory. The model was verified on the TaN-GeO2-Ni structure with good semi-quantitative agreement with experiment. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4729589]
Optical Properties of TiO2 Films Deposited by Reactive Electron Beam Sputtering
(2017-10-01)
Kruchinin, V. N.
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Perevalov, T. V.
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Atuchin, V. V.
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Gritsenko, V. A.
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Komonov, A. I.
Titanium dioxide (anatase, a-TiO2) films have been prepared by electron beam sputtering of a TiO2 target in reactive atmosphere and their structural, microstructural, and optical properties were evaluated by reflection high- energy electron diffraction (RHEED) and x-ray diffraction (XRD) analyses, atomic force microscopy (AFM), and spectroscopic ellipsometry (SE). Different reflection models for determination of film optical parameters were tested and compared. The dispersive optical parameters were defined using the Tauc-Lorentz model by SE in the photon energy range of E = 1.12-4.96 eV. The films were transparent at E < 3 eV, but noticeable absorption was detected at E > 3 eV. The bandgap was estimated at the level of E (g) ae 3.44 eV.