SIMS oxygen depth profile before (a) and after (b) ion implantation. (c) Simulated oxygen profile in Ta thin film based on 2 × 105 oxygen atoms and a 30 keV implant energy. (d) XPS depth profile of the oxygen composition before and after ion implantation.
(a) HA-ADF TEM image of the Pt-TaxOy interface with an inset schematic of the device structure. (b) EDX oxygen composition map of the same region in (a). (c) Average from line scans acquired from the highlighted box in (b).
Representative bipolar switching curves for ICOMP = 0.2, 0.5, and 1.0 mA, where the SET sweeps are shown in (a) and the RESET sweeps are in (b). The RON and ROFF are plotted versus ICOMP in (c).
Endurance plots of the (a) memory state resistances (RON and ROFF ) and (b) threshold voltages (VSET and VRESET ) graphed as a function of the switching cycle. The arrows in (a) indicate the positions of the RESET I-V curves used in the SE conduction analysis for the ICOMP = 0.2 mA device.
(a) Rrepresentative Schottky plot of RESET I-V data for a device programmed with ICOMP = 0.2 mA. Regions of SE conduction are denoted in gray. The trend line equations for the LRS and HRS SE regions are y = 3.82(x)-11.40 and y = 3.90(x)-13.73, respectively. The inset shows the ohmic conduction of the LRS and HRS regions. (b) The resistance from the LRS and HRS SE conduction regions (denoted by RLRSE and RHRSE ) plotted versus the calculated Schottky barrier height for each ICOMP (indicated by 0.2, 0.5, and 1.0). RLRSE and RHRSE were calculated at 0.36 V, which is illustrated by the vertical dashed line in (a).
Analysis of HRS I-V data showing ohmic conduction in the log–log plot in (a), SE conduction in (b), and FPE conduction in the high voltage conduction (HVC) region of (c) prior to electronic breakdown at ∼2.6 V.
Summary of the Schottky emission current fitting results.
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