We studied intrinsic resistance switching behaviour in sputter-deposited amorphous silicon suboxide (a-SiOx) films with varying degrees of roughness at the oxide-electrode interface. By combining electrical probing measurements, atomic force microscopy (AFM), and scanning transmission electron microscopy (STEM), we observe that devices with rougher oxide-electrode interfaces exhibit lower electroforming voltages and more reliable switching behaviour. We show that rougher interfaces are consistent with enhanced columnar microstructure in the oxide layer. Our results suggest that columnar microstructure in the oxide will be a key factor to consider for the optimization of future SiOx-based resistance random access memory.

In this paper, we present a study of intrinsic bipolar resistance switching in metal-oxide-metal silicon oxide ReRAM devices. Devices exhibit low electroforming voltages (typically − 2.6 V), low switching voltages (± 1 V for setting and resetting), excellent endurance of > 107 switching cycles, good state retention (at room temperature and after 1 h at 260 °C), and narrow distributions of switching voltages and resistance states. We analyse the microstructure of amorphous silicon oxide films and postulate that columnar growth, which results from sputter-deposition of the oxide on rough surfaces, enhances resistance switching behavior.

Silicon oxide-based resistive switching devices show great potential for applications in nonvolatile random access memories. We expose a device to voltages above hard breakdown and show that hard oxide breakdown results in mixing of the SiOx layer and the TiN lower contact layers. We switch a similar device at sub-breakdown fields in situ in the transmission electron microscope (TEM) using a movable probe and study the diffusion mechanism that leads to resistance switching. By recording bright-field (BF) TEM movies while switching the device, we observe the creation of a filament that is correlated with a change in conductivity of the SiOx layer. We also examine a device prepared on a microfabricated chip and show that variations in electrostatic potential in the SiOx layer can be recorded using off-axis electron holography as the sample is switched in situ in the TEM. Taken together, the visualization of compositional changes in ex situ stressed samples and the simultaneous observation of BF TEM contrast...