Peculiarities of Electrical Switching and Phase Transition Dynamics in Bismuth-Infused Se-Te Chalcogenide Glasses: From Bulk to Thin Film Devices

Abstract

Herein, the electrical switching behavior of both bulk and thin film forms of Se<inf>86-x</inf>Te<inf>14</inf>Bi<inf>x</inf> (0 ≤ x ≤ 4) chalcogenide glasses was investigated. The melt-quench-derived glasses were found to be amorphous, and the switching behavior exhibited a threshold-type response below a certain current limit (I<inf>th</inf>) for bismuth (Bi)-doped bulk samples. Interestingly, as current levels surpassed this threshold, a noteworthy change occurred in the switching behavior, converting it into a memory-type response. The threshold voltage (V<inf>th</inf>) exhibited a decreasing trend from ∼228 V to ∼36 V with an increasing Bi content, and differential scanning calorimetry (DSC) was utilized to study the phase transition phenomena and thermal stability of the amorphous glasses. These DSC results unequivocally confirmed that the transition from amorphous to crystalline phase occurred readily and at lower temperatures in the Se<inf>82</inf>Te<inf>14</inf>Bi<inf>4</inf> composition. Furthermore, annealing studies were carried out to gain insight into the phase transformations that occur when the material makes the transition from an amorphous to a crystalline state. Subsequently, the same melt-quench-derived glasses were deposited as a thin film using physical vapor deposition (PVD) into a three-layered Al/Se-Te-Bi/Al device, and the memory switching voltage experienced a remarkable drop to 2.88 V compared to the bulk material. This exploration sheds light on the captivating electrical switching behavior of Se<inf>86-x</inf>Te<inf>14</inf>Bi<inf>x</inf> chalcogenide glasses and holds promise for potential applications spanning the realm of emerging electronics and phase change material (PCM) devices. © 2024 American Chemical Society.