Threshold Switching Behavior of Ag-SiTe-Based Selector Device and Annealing Effect on its Characteristics

Abstract

Programmable metallization cell is one of important threshold switching selectors. We first performed a study on the selector based on amorphous chalcogenide material (Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.4</sub> Te <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.6</sub> ) because of the rigid structure applied in ovonic threshold switch. In the meantime, annealing process is implemented to improve the performance. Results show that devices without annealing process demonstrate a minor threshold switching characteristic, revealing the potential as selector for cross-point memristor array. After implementing annealing process, threshold voltage (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> ), selectivity and endurance of selectors improve. Meanwhile, requirements of high current and a low holding voltage (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">h</sub> ) for an ideal selector are fulfilled. Using the Ag filament formed during motion of Ag ions, a steep-slope (1.7 mV/dec) for threshold switching with high selectivity (~10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> ) could be achieved. Owing to the faster diffusivity of Ag atoms in solid-electrolytes, the resulting Ag filament easily dissolved under low current regime. It is deduced that performance improvement is due to the defect reduction within annealing process. Finally, time characteristics of selector devices are tested to verify fast switching and recovery speed for practical applicability.