Joseph L. Tedesco

Memristors With Flexible Electronic Applications

In addition to the potential for memristors to be used in logic, memory, smart interconnects, and biologically inspired architectures that could transform traditional silicon-based computing, memristors may enable such transformative technologies on physically flexible substrates. The simple structure of a memristor, which generally consists of a thin film of oxide sandwiched between two metal contacts, contributes to its compatibility with existing and future large area flexible electronics. This is especially true considering that recent work has demonstrated the ability for titanium dioxide-based memristors to be deposited from solution at room temperature by using a sol gel technique on a flexible polymer substrate. The integration of memristors with traditional flexible devices (such as thin-film organic, zinc oxide, or amorphous-Si transistors) may enable the realization of a new paradigm in computing technology through lightweight, inexpensive, flexible electronics.

Switching mechanisms in flexible solution-processed TiO2 memristors *

Memristors are emerging as unique electrical devices with potential applications in memory, reconfigurable logic and biologically inspired computing. Due to the novelty of these devices, the complete details of their switching mechanism is not yet well established. In this work, the switching mechanism of our solution-processed titanium dioxide-based memristor is investigated by studying how variations in the device area and film thickness affect electrical behavior and correlating these behavioral changes to proposed switching mechanisms. The conduction path of the switching is also investigated through electrical characterization of devices both before and after physically cutting the devices in half, as well as through infrared imaging of the devices during operation. The results suggest that the electrical behavior of these devices is dominated by a localized, charge-based phenomenon that exhibits a dependence on device area.

Flexible Memristors Fabricated through Sol-Gel Hydrolysis

Flexible memristors consisting of an oxide film generated through hydrolysis of a spun-on sol-gel were fabricated on polyethylene terephthalate substrates. X-ray photoelectron spectroscopy, spectroscopic ellipsometry, transmission electron microscopy, and electron energy loss spectroscopy measurements indicated that the oxide films contained amorphous TiO2 as well as a significant fraction of organic material. This characterization indicated that the oxide film has a different structure and morphology than sputter-deposited TiO2 memristors (“traditional memristors”). Despite the structural differences between sol-gel and traditional memristors, these flexible memristors exhibit switching behavior that is similar to sputter-deposited devices. Current-voltage (I-V) measurements suggest that this switching is not directly due to the electric field in the memristors. Additionally, thermal imaging measurements and I-V measurements performed after sectioning the memristors suggest that conduction occurred via localized conduction pathways. Capacitance-frequency and conductancefrequency measurements were also performed to further investigate conduction and loss mechanisms in these memristors.

Characterization and resistive switching properties of solution-processed HfO 2 , HfSiO 4 , and ZrSiO 4 thin films on rigid and flexible substrates

Memristors, nonvolatile bipolar resistive switching devices first intentionally fabricated in 2008 [1], have attracted attention for use in a wide range of applications. To date, most memristors have been fabricated from TiOx [1] or TaOx [2]. However, it is necessary to explore the memristive properties of other dielectric materials, because these dielectrics may have advantageous properties that have not yet been explored.