Unravelling the role of oxygen vacancies on the current transport mechanisms in all-perovskite nickelate/titanate heterojunctions for nonvolatile memory applications

• Published in: Journal of applied physics 2022-10, Vol.132 (13)
• Main Authors: Zhang, Yong, Gao, Shunhua, Ma, Chunrui, Lu, Lu, Han, Chuan Yu, Liu, Ming
• Format: Article
• Language: English
• Subjects: Applied physics; Contact stresses; Electric contacts; Electric fields; Electric potential; Heterojunctions; High temperature; Leakage current; Oxygen; Perovskites; Space charge; Voltage
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/5.0111879

The micrometer-sized nickelate–titanate heterojunctions with LaNiO3 (LNO) electrode have been fabricated to investigate the dominant current transport mechanisms under positive and negative bias. The LNO/SmNiO3 (SNO)/Nb:SrTiO3 (NSTO) heterojunction exhibits a highly rectifying feature with a very low leakage in a broad temperature region (from 200 to 425 K), which is attributed to the formation of a Schottky-like barrier at the SNO/NSTO interface. In addition, it is found that the trap defects (i.e., oxygen vacancies) play an essential role in determining the current density (J)–voltage (V) characteristics irrespective of the voltage polarity. The leakage current at low electric fields (1.2 MV/cm), the leakage is ascribed to the bulk-limited field enhanced thermal ionization of trapped carriers in the SNO film (i.e., Poole–Frenkel emission). Specially, the oxygen vacancy redistribution near the SNO/NSTO heterointerface driven by a high temperature (425 K) or high electrical field (>3.8 MV/cm) stress is emphasized to account for the transition from the Schottky contact limited to bulk-limited conduction mechanism (i.e., space charge limited conduction). This work will benefit the further analysis of the resistive switching phenomena in nickelate-based devices, showing a potential for nonvolatile memory applications.