Internal stresses and formation of switchable nanowires at thin silica film edges

Abstract

At vertical edges, thin films of silicon oxide (SiO2−x) can contain defect-free semiconductive c-Si layered nanocrystals (Si NC) embedded in and supported by an insulating g-SiO2 matrix. Yaoet al. [Appl. Phys. A (in press)] have shown that a trenched thin film geometry enables the NC to form switchable nanowires (SNW) when trained by an applied field. The field required to form SNW decreases rapidly within a few cycles, or by annealing at 600 °C in even fewer cycles, and is stable to 700 °C. Here we describe the intrinsic evolution of Si NC and SNW in terms of the competition between internal stresses and electro-osmosis. The analysis relies heavily on experimental data from a wide range of thin film studies, and it explains why a vertical edge across the planar polySi-SiO2−x interface is necessary to form SNW. The discussion also shows that the formation mechanisms of Si NC and polySi/SiO2−x SNW are intrinsic and result from optimization of nanowire connectivity in the presence of residual host misfit stresses.

In situ imaging of the conducting filament in a silicon oxide resistive switch

“…3D) indicates the possible amorphization process. This is consistent with the thermally induced amorphization observed in the metallic Si phases (18,20), as the reset process in unipolar resistive switching is largely thermally stress-driven (2,9,23). In particular, resistance increase is associated with the amorphization process (18).…”