An electronic silicon-based memristor with a high switching uniformity

Abstract

Amorphous insulators have localized wave functions that decay with the distance $r$ following exp($-r/\zeta$). Since nanoscale conduction is not excluded at $r<\zeta$, one may use amorphous insulators and take advantage of their size effect for nanoelectronic applications. Voltage-regulated nanoscale conductivity is already utilized in metal-insulator-metal devices known as memristors. But typically their tunable conductivity does not come from electrons but from migrating ions within a stoichastically formed filament, and as such their combined resistor-memory performance suffers. Here we demonstrate amorphous-silicon-based memristors can have coherent electron wave functions extending to the full device thickness, exceeding 15 nm. Remarkably, despite the large aspect ratio and very thin thickness of the device, its electrons still follow an isotropic, three-dimensional pathway, thus providing uniform conductivity at the nanometer scale. Such pathways in amorphous insulators are derived from overlapping gap states and regulated by trapped charge, which is stabilized by electron-lattice interaction; this makes the memristor exhibit pressure-triggered insulator$\rightarrow$metal transitions. Fast, uniform, durable, low-power and purely electronic memristors with none of the shortcomings of ion-migrating memristors have been fabricated from a variety of amorphous silicon compositions and can be readily integrated into silicon technology. Therefore, amorphous silicon may provide the ideal platform for building proximal memories, transistors and beyond.