We have investigated the impact of O2 annealing after SiOx deposition on the switching behavior to gain a better understanding of the resistance switching mechanism, especially the role of oxygen deficiency in the SiOx network. Although resistive random access memories (ReRAMs) with SiOx after 300 annealing sandwiched with Pt electrodes showed uni-polar type resistance switching characteristics, the switching behaviors were barely detectable for the samples after annealing at temperatures over 500. Taking into account of the average oxygen content in the SiOx films evaluated by XPS measurements, oxygen vacancies in SiOx play an important role in resistance switching. Also, the results of conductive AFM measurements suggest that the formation and disruption of a conducting filament path are mainly responsible for the resistance switching behavior of SiOx.

An SiO2/Si-cap/Si0.55Ge0.45 heterostructure was fabricated on p-type Si(100) and strained silicon on insulator (SOI) substrates by low pressure chemical vapor deposition (LPCVD) and subsequent thermal oxidation in an O2 + H2 gas mixture. Chemical bonding features and valence band offsets in the heterostructures were evaluated by using high-resolution x-ray photoelectron spectroscopy (XPS) measurements and thinning the stack layers with a wet chemical solution.

We have fabricated Pt/Si-rich oxide (SiOx)/TiN stacked MIM diodes and studied an impact of the structural asymmetry on their resistive switching characteristics. XPS analyses show that a TiON interfacial layer was formed during the SiOx deposition on TiN by RF-sputtering in an Ar + O2 gas mixture. After the fabrication of Pt top electrodes on the SiOx layer, and followed by an electro-forming process, distinct bi-polar type resistive switching was confirmed. For the resistive switching from high to low resistance states so called SET process, there is no need to set the current compliance. Considering higher dielectric constant of TiON than SiOx, the interfacial TiON layer can contribute to regulate the current flow through the diode. The clockwise resistive switching, in which the reduction and oxidation (Red-Ox) reactions can occur near the TiN bottom electrode, shows lower RESET voltages and better switching endurance than the counter-clockwise switching where the Red-Ox reaction can take place near the top Pt electrode. The result implies a good repeatable nature of Red-Ox reactions at the interface between SiOx and TiON/TiN in consideration of relatively high diffusibility of oxygen atoms through Pt.