Researchers create nondestructive technique to study atomic switching
Researchers create nondestructive technique to study atomic switching lead image
Atomic switches have emerged as a promising resistive memory technology due to their high density, large scalability and low power consumption. The switching mechanism is created through the formation and rupture of atomic-scale conductive metal filaments by applying a voltage to induce electrochemical reactions within a solid oxide electrolyte sandwiched between two metal electrodes.
Because the high-resistance (OFF) state is determined by the previous rupture process (RESET) and affects the subsequent formation process, a clear understanding of the filament structure and the electronic states in the OFF state is needed to advance the technology. However, observing the embedded filaments has been difficult and requires complicated preparations to prevent material damage.
To address this problem, Aiba et al. demonstrated a nondestructive technique based on current-voltage measurements for electron tunneling analysis. They used the technique to study the effects of moisture on filament growth – an important aspect to consider in enabling atomic switches to perform under ambient conditions.
The researchers fabricated an atomic switch using tantalum oxide as the filament material sandwiched between gold and platinum electrodes. To determine the effects of water adsorption in the OFF state, they studied the changes in the size and potential barrier of ruptured filaments as water molecules were added and removed.
They found the cross-sectional area of ruptured filaments increased and the potential barrier for tunneling decreased when water molecules were introduced. The finding shows that, at low operating voltage, moisture supports large filament growth, which contributes to stable switching.
The research could be used to evaluate novel devices for chemical and humidity sensor applications. The researchers plan to next evaluate the effects of other molecules.
Source: “Effects of water adsorption on conductive filaments of a Ta2O5 atomic switch investigated by nondestructive electrical measurements,” by A. Aiba, S. Kaneko, T. Tsuruoka, K. Terabe, M. Kiguchi, and T. Nishino, Applied Physics Letters (2019). The article can be accessed at https://doi.org/10.1063/5.0028013 .
