Biomaterial-Induced Stable Resistive Switching Mechanism in TiO 2 Thin Films: The Role of Active Interstitial Sites/Ions in Minimum Current Leakage and Superior Bioactivity

ACS Omega. 2020 Jul 21;5(30):19050-19060. doi: 10.1021/acsomega.0c02410. eCollection 2020 Aug 4.

Abstract

Leakage of current in oxide layers is the main issue for higher speed and denser resistive random-access memory. Defect engineering played a substantial role in meeting this challenge by doping or producing controlled interstitial defects or active sites. These controlled active sites enabled memory cells to form a stable and reproducible conduction filament following an electrochemical metallization model. In this study, a defect-abundant lime peel extract (LPE)-mediated anatase TiO2 thin film was fabricated using a simple hydrothermal route. The detailed structural and morphological analysis of the bioactive anatase TiO2-LPE thin film reveals the homogeneous growth of TiO2 flowers and distinct features in terms of controlled defects as compared to simple anatase TiO2. These interstitial defects (Ti+3 and Ti+4) behave as active sites for cation migrations along highly conductive K1+ ions because of the mediation of LPE. The defect-free surface reveals slight surface roughness (4.8 nm) that successfully minimizes leakage of current. The strategy enabled a reliable conductive bridge filament, which can replicate with no more electric degradation. The Ag/TiO2-LPE/FTO-based memory cell demonstrates reproducible bipolar resistive switching along with a high ON/OFF ratio (>105), excellent endurance (1.5 × 103 cycles), and long-term retention (105 s) without any electrical degradation. Furthermore, green-synthesized TiO2-LPE nanoparticles have shown superior antibacterial activity as compared to other green syntheses of different plants or fruits against the toxic microorganisms present in inorganic media.