SiAlON thin films on silicon and formation of nanofilaments with memristive properties

Memristors are devices that change its resistance depending on the current that flows through. It is a reversible process where the material is typically cycled between two resistive states (ON conductive and OFF resistive)... [ view full abstract ]

Memristors are devices that change its resistance depending on the current that flows through. It is a reversible process where the material is typically cycled between two resistive states (ON conductive and OFF resistive) [1]. These changes are attributed to the generation of nanofilaments along the material, which can be interrupted and reconnected [2]. Silicon aluminum oxinitride (SiAlON) is well known for its mechanical and optoelectronic properties, and accidentally we found that nanolayers behaved like memristors. The purpose of this work consists in the study of SiAlON as a memristive material with outstanding properties.
Devices were fabricated with a structure of a SiAlON thin film between two electrodes. The thin film of 165 nm was grown onto a Silicon substrate with the Pulsed Laser Deposition technique. Electrodes were obtained with the Electron Beam Evaporation by using a dark mask. Aluminum and Indium Tin Oxides (ITO) were used as electrodes; however the work was mainly focused in the use of aluminum. To measure changes in resistance, electrical tests were performed ramping up voltage and observing abrupt changes in intensity.
The results showed an average resistance of 1 MΩ in the OFF state and 100 Ω in the ON; which represents a difference of four orders of magnitude between states (Figure 1.a). The conductive paths are very similar, except from the first process called the forming, which is more irregular due to the generation of nanofilaments. Resistive switching cycles were obtained by using alternate opposite voltages and the same voltage in both states. Apart from the two main states, it was possible to obtain different intermediate states by controlling the maximum voltage of the process (Figure 1.b). Devices maintained each state for a day and the processes may have characteristic repercussions in their surface.
In conclusion, the formation of Al nanofilaments induces extremely good and controllable memristive properties in SiAlON. There is a change in more than four orders of magnitude of resistance between the two stable sates. The change between the states is very abrupt and extremely fast (faster than ns) and the devices appear ciclable without losing their memristive properties.