XPS results for CuO, CuO/6F-HBC, and 6F-HBC samples after sputter time of 12 min. (a) XPS C1s peak due to fluorinated carbon shows the shift of 0.68 eV towards higher binding energy for CuO/6F-HBC IL with respect to that of 6F-HBC sample. (b) O1s spectra showing two peaks in CuO sample corresponding to the lattice oxygen and “non lattice” oxygen of CuO. The two peaks observed for CuO/6F-HBC are shifted by 0.6 eV towards lower binding energy side as compared to those in CuO sample (c) The Cu 2p spectra for CuO sample show a single peak, whereas CuO/6F-HBC sample shows two peaks, one corresponds to the cupric phase and other corresponds to the interfacial interaction. (d) Tabulated results for peak positions in C1s, O1s, and Cu2p spectra for CuO, 6F-HBC samples, and CuO/6F-HBC interface.
I-V curves showing (a) the rectifying characteristic for Ti-CuO-Cu, (b) ohmic behaviour for Ti-(6F-HBC)-Cu, and (c) rectifying characteristic before electroforming for Ti-CuO/(6F-HBC)-Cu junction showing hysteresis. (d) The schematic view of the sample for the I-V measurement.
(a) Current-voltage characteristic of Ti-CuO-(6F-HBC)-Cu sample during initial electroforming step showing transition to LRS at VF of 3.06 V with a current compliance limit (ICC) of 10 mA. (b) I-V curve showing reversible and bipolar resistive switching in Ti-CuO-(6F-HBC)-Cu sample. The sample switches from LRS to HRS at reset voltage (VR) of −1.42 V and switches back to LRS at set voltage (VS) of 1.62 V. The arrow indicates the sweep direction. (c) and (d) I-V characteristics showing the linear ohmic behaviour with slope of about 1.02 and 0.99 in the LRS for the positive and negative bias regions, respectively, in a double-logarithmic plot. Linearity is also observed in HRS at lower voltages with the slope of about 1.03 and 1.04 for both the regions. Deviation from the linearity is observed in HRS at higher voltages with the slope of about 2.13 and 2.03 for positive and negative regions, respectively.
(a) Retention characteristics of device in HRS and LRS measured at 85 °C for 105 s. (b) Typical bipolar resistive switching behaviour of the Ti-CuO/(6F-HBC)-Cu device switched by DC voltage sweeps. (c) Distribution of set and reset voltages and (d) device resistance in LRS and HRS up to ∼200 switching cycles showing well resolved two stable states.
(a) and (b) Show the current images of the CuO/6F-HBC memory cell in LRS and HRS, respectively, overlapped with their topography images indicating that majority of conducting regions (indicated by white mosaics) seem to be located at the grain boundaries. (c) and (d) Show the current images of the Cu2O memory cell in LRS and HRS, respectively, overlapped with their topography images having uniform nanosized filaments homogeneously dispersed over the entire topographical features. Topography and current images for Cu2O cells from our earlier study are given for comparison. 23
(a) CAFM based localized I-V curves measured on nanoscale conducting (C), non-conducting (NC) regions in LRS, and pristine sample. (b) Bipolar resistive switching observed using CAFM tip as the top electrode.
Schematic illustration for the alignment of organic layer of (a) HBC and (b) 6F-HBC on CuO (111) plane. Insets in (a) and (b) show the schematic view of single molecule of HBC and 6F-HBC, respectively. The different colors are used for the ease of identification.
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