Electroforming-Free Bipolar Resistive Switching in GeSe Thin Films with a Ti-Containing Electrode

Chalcogenide materials have been regarded as strong candidates for both resistor and selector elements in passive crossbar arrays owing to their dual capabilities of undergoing threshold and resistance switching. This work describes the bipolar resistive switching (BRS) of amorphous GeSe thin films, which used to show Ovonic threshold switching (OTS) behavior. The behavior of this new functionality of the material follows filament-based resistance switching when Ti and TiN are adopted as the top and bottom electrodes, respectively. The detailed analysis revealed that the high chemical affinity of Ti to Se produces a Se-deficient Ge_xSe_1–x matrix and the interfacial Ti–Se layer. Electroforming-free BRS behavior with reliable retention and cycling endurance was achieved. The performance improvement was attributed to the Ti–Se interfacial layer, which stabilizes the composition of GeSe during the electrical switching cycles by preventing further massive Se migration to the top electrode. The conduction mechanism analysis denotes that the resistance switching originates from the formation and rupture of the high-conductance semiconducting Ge-rich Ge_xSe_1–x filament. The high-resistance state follows the modified Poole–Frenkel conduction.