Scalable 3D Ta:SiO_x Memristive Devices

Abstract

and hence is more bit cost-efficient. [25] However, 3D vertical structure with SiO x switching layer has not been achieved yet.Herein, we report a Ta:SiO 2 device with reliable bipolar memristive switching. After introducing Ta cations, our devices showed high uniformity, superior endurance (>10 9 cycles), fast switching speed, reliable retention, and analog modulation of device conductance. In addition, we studied the scaling ability of the Ta:SiO 2 -based 3D vertical devices with sizes ranging from micro-to nanoscale (as small as 60 × 15 nm 2 ). The switching behavior shows weak dependence on area size when the device is relatively large; after that, state conductance and the operation current decrease when the device is further scaled down. We built 3D devices and achieved similar memristive behavior from both the top and bottom cells in a two-layer vertical device. Our work confirms that doping SiO x is an efficient way to tailor properties of memristive devices, which has great scalability and stackability. Results and Discussion Ta:SiO 2 Thin Films Prepared by Co-SputteringThe Ta:SiO 2 thins film were prepared by co-sputtering from Ta and SiO 2 targets. Figure 1 schematically shows the principle of the co-sputtering process, in which two targets are sputtered simultaneously in the chamber. The SiO 2 target was sputtered at a constant radiofrequency (RF) power of 270 W, while the Ta target was sputtered with varied direct current (DC) powers ranging from 0 to 20 W. The atomic ratios for Ta dopants sputtered at 10 and 20 W were determined to be 14.1% and 22.5%, respectively. More importantly, the Ta in the thin films is in different valence states, as revealed by X-ray photoemission spectroscopic (XPS) characterization (Figure 2). The Ta 4f XPS spectra from films after 4 min Ar + sputtering inside the chamber were deconvolved into three chemical states of Ta: fully oxidic (Ta 5+ ), suboxidic, and metallic states. [29] The atomic ratios of the three states were calculated to be 57.65%/25.97%/16.39% (Figure 2a) and 34.91%/29.81%/35.28% (Figure 2b), respectively, for the two films prepared with different DC powers on Ta. The concentration of the Ta metallic state increased evidently in the film with a higher Ta sputtering power.From electrical measurements (see Figure S1 in the Supporting Information), the device without Ta doping was hard breakdown, while the device based on Ta 22.5% :SiO 2 was directly shorted. On the contrary, reliable memristive switching A highly reliable memristive device based on tantalum-doped silicon oxide is reported, which exhibits high uniformity, robust endurance (≈1 × 10 9 cycles), fast switching speed, long retention, and analog conductance modulation. Devices with junction areas ranging from microscale to as small as 60 × 15 nm 2 are fabricated and electrically characterized. ON-/OFF-conductance and reset current show weak area dependence when the device is relatively large, and they become proportional to the device area when further scaled down. Two-layer devices with repeatabl...

Influence of junction resistance on spatiotemporal dynamics and reservoir computing performance arising from an SWNT/POM 3D network formed via a scaffold template technique

“…12,31 Simultaneously 3D RC has been investigated extensively in 3D memristor arrays 22,[32][33][34] and quasi-3D nanowire networks. 35,36 For instance, a 3D memristive in materio RC array has been reported following an approach similar to that of IC fabrication 37,38 . However, such devices' mass production and utilization are not feasible due to the complicated fabrication process.…”