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Abstract Ultrathin (sub-2 nm) Al2O3/MgO memristors were recently developed using anin vacuoatomic layer deposition (ALD) process that minimizes unintended defects and prevents undesirable leakage current. These memristors provide a unique platform that allows oxygen vacancies (VO) to be inserted into the memristor with atomic precision and study how this affects the formation and rupture of conductive filaments (CFs) during memristive switching. Herein, we present a systematic study on three sets of ultrathin Al2O3/MgO memristors with VO-doping via modular MgO atomic layer insertion into an otherwise pristine insulating Al2O3atomic layer stack (ALS) using anin vacuoALD. At a fixed memristor thickness of 17 Al2O3/MgO atomic layers (∼1.9 nm), the properties of the memristors were found to be affected by the number and stacking pattern of the MgO atomic layers in the Al2O3/MgO ALS. Importantly, the trend of reduced low-state resistance and the increasing appearance of multi-step switches with an increasing number of MgO atomic layers suggests a direct correlation between the dimension and dynamic evolution of the conducting filaments and the VOconcentration and distribution. Understanding such a correlation is critical to an atomic-scale control of the switching behavior of ultrathin memristors.
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Atomic-scale tuning of ultrathin memristors
Abstract Continuous device downsizing and circuit complexity have motivated atomic-scale tuning of memristors. Herein, we report atomically tunable Pd/M1/M2/Al ultrathin (<2.5 nm M1/M2 bilayer oxide thickness) memristors using in vacuo atomic layer deposition by controlled insertion of MgO atomic layers into pristine Al2O3atomic layer stacks guided by theory predicted Fermi energy lowering leading to a higher high state resistance (HRS) and a reduction of oxygen vacancy formation energy. Excitingly, memristors with HRS and on/off ratio increasing exponentially with M1/M2 thickness in the range 1.2–2.4 nm have been obtained, illustrating tunneling mechanism and tunable on/off ratio in the range of 10–104. Further dynamic tunability of on/off ratio by electric field is possible by designing of the atomic M2 layer and M1/M2 interface. This result probes ways in the design of memristors with atomically tunable performance parameters.
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- PAR ID:
- 10377043
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Communications Physics
- Volume:
- 5
- Issue:
- 1
- ISSN:
- 2399-3650
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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