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

Abstract

The nature of the conducting filaments in many resistive switching systems has been elusive. Through in situ transmission electron microscopy, we image the real-time formation and evolution of the filament in a silicon oxide resistive switch. The electroforming process is revealed to involve the local enrichment of silicon from the silicon oxide matrix. Semi-metallic silicon nanocrystals with structural variations from the conventional diamond cubic form of silicon are observed, which likely accounts for the conduction in the filament. The growth and shrinkage of the silicon nanocrystals in response to different electrical stimuli show energetically viable transition processes in the silicon forms, offering evidence for the switching mechanism. The study here also provides insights into the electrical breakdown process in silicon oxide layers, which are ubiquitous in a host of electronic devices.

Carbon nanotube network-silicon oxide non-volatile switches

“…While the mechanism for creating a LRS is well understood 10,11 , it is not clear what mechanism is responsible for returning the device to a HRS. Previous in-situ TEM measurements show that after switching to a HRS, the nanocrystal Si filament shrinks but is still present 11 . Consistent with previous work from refs 10,18, the switching behaviour is unipolar with V HRS greater than V LRS , unlike conventional unipolar RRAM switching behaviour.…”

“…However, in this case unipolar switching behaviour is observed because electrical contact is not broken until the CNTs undergo oxidation. Finally, we rule out amorphization of the Si nano-crystals as a switching mechanism 11 . The measurements in this study were performed using continuous voltage sweeps rather than pulsed voltages.…”

“…It is known, however, that the type of metal used to contact the insulator may influence this switching mechanism 5,6 . Regarding the insulator, while it is typical to use some kind of metal oxide [7][8][9] (for example, AlO x , HfO x , TiO x ) in the MIM cell, recently it was discovered that even silicon oxide could be switched between a HRS and a LRS [10][11][12] .…”

Field‐ and irradiation‐induced phenomena in memristive nanomaterials

“…Taking into account that the I-V curve in LRS is linear for the SiO 2 -based devices [23], one can assume that we deal with the so called 'metallic forms' of silicon filaments [33]. Another explanation of the high LRS current relies evidently on the assumption of multiple filaments formation.…”

Electrochemical dynamics of nanoscale metallic inclusions in dielectrics

“…In these devices, the resistive switching is normally attributed to filament formation caused by the movement of metal inclusions in the insulating dielectric film 9,10,[18][19][20] . Attempts to microscopically study the filament growth processes have been carried out using scanning probe microscopy 15,21 and highresolution transmission electron microscopy 19,20,[22][23][24] techniques. For example, a recent experiment reveals different filament growth modes 20 and shows that filament formation can be achieved in the form of metal nanoclusters.…”