Resistance Switching in Polycrystalline C12A7 Electride.

The memory (memristive) properties of an electride material based on polycrystalline mayenite (C12A7:e-) were studied. The phase composition of the material has been confirmed by such methods as XRD, TEM, Raman, and infrared spectroscopy. The electride state was confirmed by conductivity measurements and EPR using a characteristic signal from F+-like centers, but the peak at 186 cm-1, corresponding to an electride with free electrons, was not observed explicitly in the Raman spectra. The temperature dependence of current-voltage characteristics in states with low and high resistance (LRS and HRS) has been studied. In the LRS state, the temperature dependence of the current has a non-Arrhenius character and is described by the Hurd quantum tunnelling model with a Berthelot temperature of 262 K, while in the HRS state, it can be described in terms of the Arrhenius model. In the latter case, the existence of two conduction regions, "impurity" and "intrinsic", with corresponding activation energies of 25.5 and 40.6 meV, was assumed. The difference in conduction mechanisms is most likely associated with a change in the concentration of free electrons.

Radiation-Induced Nucleation and Growth of CaSi2 Crystals, Both Directly during the Epitaxial CaF2 Growth and after the CaF2 Film Formation.

The radiation-induced phenomena of CaSi2 crystal growth were investigated, both directly during the epitaxial CaF2 growth on Si (111) and film irradiation with fast electrons on Si (111) after its formation, while maintaining the specified film thickness, substrate temperature and radiation dose. Irradiation in the process of the epitaxial CaF2 film growth leads to the formation of CaSi2 nanowhiskers with an average size of 5 µm oriented along the direction <110>. The electron irradiation of the formed film, under similar conditions, leads to the homogeneous nucleation of CaSi2 crystals and their proliferation as inclusions in the CaF2 film. It is shown that both approaches lead to the formation of CaSi2 crystals of the 3R polymorph in the irradiated region of a 10 nm thick CaF2 layer.

Charge transport mechanism in the forming-free memristor based on silicon nitride.

Nonstoichiometric silicon nitride SiNx is a promising material for developing a new generation of high-speed, reliable flash memory device based on the resistive effect. The advantage of silicon nitride over other dielectrics is its compatibility with the silicon technology. In the present work, a silicon nitride-based memristor deposited by the plasma-enhanced chemical vapor deposition method was studied. To develop a memristor based on silicon nitride, it is necessary to understand the charge transport mechanisms in all states. In the present work, it was established that the charge transport in high-resistance states is not described by the Frenkel effect model of Coulomb isolated trap ionization, Hill-Adachi model of overlapping Coulomb potentials, Makram-Ebeid and Lannoo model of multiphonon isolated trap ionization, Nasyrov-Gritsenko model of phonon-assisted tunneling between traps, Shklovskii-Efros percolation model, Schottky model and the thermally assisted tunneling mechanisms. It is established that, in the initial state, low-resistance state, intermediate-resistance state and high-resistance state, the charge transport in the forming-free SiNx-based memristor is described by the space charge limited current model. The trap parameters responsible for the charge transport in various memristor states are determined.

Electronic structure and charge transport mechanism in a forming-free SiO x -based memristor.

THe memristor is a key memory element for neuromorphic electronics and new generation flash memories. One of the most promising materials for memristor technology is silicon oxide SiO x , which is compatible with silicon-based technology. In this paper, the electronic structure and charge transport mechanism in a forming-free SiO x -based memristor fabricated with the plasma enhanced chemical vapor deposition method is investigated. The experimental current-voltage characteristics measured at different temperatures in high-resistance, low-resistance and intermediate states are compared with various charge transport theories. The charge transport in all states is limited by the space charge-limited current model. The trap parameters, responsible for the charge transport in a SiO x -based memristor in different states, are determined.