(Color online) X-ray diffraction patterns of 50 nm HfO2 with TiN/Ti TE. HfO2 films were polycrystalline with a monoclinic structure. The inset shows the cross-sectional TEM image, showing an interfacial layer between HfO2 and Si.
(Color online) (a) Typical bipolar resistive-switching curves of HfO2 with TiN/Ti, Ta, Pt, Cu, and Ni top electrodes. Samples with the Cu and Ni top electrodes were under negative forming. (b) Typical nonpolar resistive-switching curves of HfO2 with Cu and Ni top electrodes under positive forming.
(Color online) Bipolar DC-IV cycling of HfO2 with TiN/Ti TE. Notable variations exist in SET and RESET voltages.
Statistical distribution of switching voltages of (a) bipolar resistive-switching with TiN/Ti, Ta, and Pt TEs, and (b) nonpolar resistive-switching with Cu and Ni TEs (only unipolar RS with positive polarity is plotted). At least 30 switching cycles were measured for each condition.
(Color online) EDX depth profiles of atomic percentage ratio of oxygen over hafnium in the bulk HfO2 film before and after positive forming. The inset shows a cross-sectional TEM image showing the EDX probing positions of the TiN/Ti/HfO2/Si stack.
(Color online) Backside SIMS profiles of Hf, O, and Ni in a Ni/HfO2/Si stack before and after positive forming. The direction of backside profiling is also indicated.
(Color online) Unipolar DC-IV cycling of HfO2 with (a) Cu TE and (b) Ni TE.
(Color online) Double logarithmic plot of HRS I-V curves with Cu and Ni TEs. The slope of 1 indicates the ohmic conduction, while the slopes of 2 and 4 indicate the trap-free and trap-fill-limited SCLC, respectively.
(Color online) The dependence of V RESET on R LRS for the DC switching cycles in Fig. 7 . Both the lateral-linked and single filaments participated in the switching of the Cu TE sample, while the lateral-linked filaments dominated in the Ni TE sample.
(Color online) (a) Demonstration of the bipolar recovery scheme to restore the soft error of unipolar RESET in a Ni TE device. The operation sequence is labeled as (1)–(4). (b) 300 unipolar-switching cycles of HfO2 with the Ni TE facilitated by the bipolar recovery scheme. Three recovery events are indicated by the arrows.
(Color online) (a) Temperature dependence of the LRS resistance, and (b) LRS retention after baking for 100 min at an elevated temperature for the TiN/Ti/HfO2/Si and Ni/HfO2/Si devices. The compliance current at V SET are set to be 100 μA for all devices.
Article metrics loading...
Full text loading...