(Color) (a) Composite AFM-EFM image of a lateral MIM junction defined by local anodic oxidation by SPM of 10 nm thick Ti films deposited on SiO2. The color is keyed to the EFM response upon applying a dc bias to the Ti electrodes, portraying an enhanced electric field gradient at the junction. This provides a demonstration of the insulating nature of the barrier material. The double feature that is seen in the AFM micrograph comes from a double tip effect created during the oxidation process. (b) Composite AFM-EFM image of the MIM junction after forming step; the color is keyed to the electric field gradient, as measured by EFM; inset: forming IV characteristics.
(Color) Pinched hysteretic IV loops in a MIM junction. Inset: setup for electrical measurement. Arrows indicate the bias scan sequence within each frequency-dependant switching process. Green and yellow dashed lines in the low frequency (red) IV loops show the bistable resistance state with opposite rectifying IV curves. A dc bias with a constant switching rate (triangular wave) is applied for electrical measurements.
(Color) STEM-EELS spectra of Ti and TiOx for (a) Ti L2;3 core-loss and (b) O K core loss. Inset shows a high angular annular dark-field image (HAADF) in STEM mode.
(Color online) (a) Forward rectifier switching schematics. Vacancies (V0) leave the right contact (oxidation and Schottky barrier formation) moving toward left side of the device upon an applied electric field, thus creating a forward biased rectifier. (b) Backward rectifier switching schematics. Vacancies (V0) leave the left contact (oxidation and Schottky barrier formation) moving toward the right side of the device upon an applied electric field, thus reducing the TiO2 and providing an ohmic contact. (c) Equivalent circuit for the lateral MIM junctions.
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