Atomic Layer Deposited Oxide-Based Nanocomposite Structures with Embedded CoPt_x Nanocrystals for Resistive Random...

Al₂O₃- or HfO₂-based nanocomposite structures with embedded CoPt_x nanocrystals (NCs) on TiN-coated Si substrates have been prepared by combination of thermal atomic layer deposition (ALD) and plasma-enhanced ALD for resistive random access memory (RRAM) applications. The impact of CoPt_x NCs and their average size/density on the resistive switching properties has been explored. Compared to the control sample without CoPt_x NCs, ALD-derived Pt/oxide/100 cycle-CoPt_x NCs/TiN/SiO₂/Si exhibits a typical bipolar, reliable, and reproducible resistive switching behavior, such as sharp distribution of RRAM parameters, smaller set/reset voltages, stable resistance ratio (≥10²) of OFF/ON states, better switching endurance up to 10⁴ cycles, and longer data retention over 10⁵ s. The possible resistive switching mechanism based on nanocomposite structures of oxide/CoPt_x NCs has been proposed. The dominant conduction mechanisms in low- and high-resistance states of oxide-based device units with embedded CoPt_x NCs are Ohmic behavior and space-charge-limited current, respectively. The insertion of CoPt_x NCs can effectively improve the formation of conducting filaments due to the CoPt_x NC-enhanced electric field intensity. Besides excellent resistive switching performances, the nanocomposite structures also simultaneously present ferromagnetic property. This work provides a flexible pathway by combining PEALD and TALD compatible with state-of-the-art Si-based technology for multifunctional electronic devices applications containing RRAM.