Thin V 2 O 5 films synthesized by plasma-enhanced atomic layer deposition for memristive applications.

In the present study, the V 2 O 5 films synthesized by plasma-enhanced atomic layer deposition on p-Si and fluorinated graphene on Si (or FG/Si) substrates were analyzed for memristive applications. A number of samples were grown with V 2 O 5 films with an average thickness of 1.0-10.0 nm, as determined by ellipsometric measurements. The study of surface morphology by atomic force microscopy showed that an island growth occurs in the initial stages of the film growth. The Raman spectra of the synthesized V 2 O 5 films with an average thickness of more than 2.0 nm on the SiO 2 /Si substrates exhibit six distinct modes typical of the orthorhombic V 2 O 5 phase. A large hysteresis was found in the C - V characteristics of the V 2 O 5 films with a thickness of 1.0-4.2 nm. In general, the built-in charge in the V 2 O 5 layers with an average thickness of 1.0-4.0 nm is positive and has a value of about ∼(2-8) × 10 11 cm -2 at the 1 MHz frequency. Increasing the V 2 O 5 film thickness leads to the accumulation of negative built-in charge up to -(1.7 to 2.3) × 10 11 cm -2 at the 1 MHz frequency. The temperature dependence of the conductivity exhibits different electrically active states in V 2 O 5 /Si and V 2 O 5 /FG/Si structures. Thus, the FG layer can modify these states. V 2 O 5 layers with an average film thickness of 1.0-3.6 nm demonstrate the memristive switching with an ON/OFF ratio of ∼1-4 orders of magnitude. At film thicknesses above 5.0 nm, the memristive switching practically vanishes. V 2 O 5 films with an average thickness of 3.6 nm were found to be particularly stable and promising for memristive switching applications.