In situ observation of indium filament growth dynamics in ITO electrode-based memristor

Indium tin oxide (ITO) electrode is commonly used in integrated transparent electronics, including memristor, solar cell, light emitting diode, and photodetector. However, the lack of appropriate understanding of indium (In) ions motion from ITO is the major roadblock to disclose the mechanism of ITO electrode-based memristors. Revealing the filaments growth dynamics is of critical importance to continued devices optimization. Here, we show direct evidence of In filament growth dynamics by in situ transmission electron microscopy, where the In–O bond in ITO would dissociate at high electric field, leading to the In ions transport and cone-like filament formation in the dielectric layer. The In filament formation and melt are responsible for the resistive switching, which can both commence growth toward active ITO and inert Au electrodes, respectively, by controlling the ion mobility. This study can provide a generalized guideline for high performance electronics design and modeling with transparent ITO electrodes.