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Aguirre FL, Piros E, Kaiser N, Vogel T, Petzold S, Gehrunger J, Hochberger C, Oster T, Hofmann K, Suñé J, Miranda E, Alff L. Revealing the quantum nature of the voltage-induced conductance changes in oxygen engineered yttrium oxide-based RRAM devices. Sci Rep 2024; 14:1122. [PMID: 38212346 PMCID: PMC10784569 DOI: 10.1038/s41598-023-49924-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 12/13/2023] [Indexed: 01/13/2024] Open
Abstract
In this work, the quasi-analog to discrete transition occurring in the current-voltage characteristic of oxygen engineered yttrium oxide-based resistive random-access memory (RRAM) devices is investigated in detail. In particular, the focus of our research is not on the absolute conductance values of this characteristic but on the magnitude of its conductance changes occurring during the reset process of the device. It is found that the detected changes correspond to conductance values predominantly of the order of the quantum unit of conductance G0 = 2e2/h, where e is the electron charge and h the Planck constant. This feature is observed even at conductance levels far above G0, i.e. where electron transport is seemingly diffusive. It is also observed that such behavior is reproducible across devices comprising yttrium oxide layers with different oxygen concentrations and measured under different voltage sweep rates. While the oxygen deficiency affects the total number of quantized conductance states, the magnitude of the changes in conductance, close to 1 G0, is invariant to the oxygen content of the functional layer.
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Affiliation(s)
- F L Aguirre
- Departament d'Enginyeria Electrònica, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Valles, Spain.
- Intrinsic Semiconductor Technologies, Ltd., Buckinghamshire, United Kingdom.
| | - E Piros
- Advanced Thin Film Technology Division, Institute of Materials Science, Technische Universität Darmstadt, Darmstadt, Germany.
| | - N Kaiser
- Advanced Thin Film Technology Division, Institute of Materials Science, Technische Universität Darmstadt, Darmstadt, Germany
| | - T Vogel
- Advanced Thin Film Technology Division, Institute of Materials Science, Technische Universität Darmstadt, Darmstadt, Germany
| | - S Petzold
- Advanced Thin Film Technology Division, Institute of Materials Science, Technische Universität Darmstadt, Darmstadt, Germany
| | - J Gehrunger
- Computer Systems Group, Department of Electrical Engineering and Information Technology, Technische Universität Darmstadt, Darmstadt, Germany
| | - C Hochberger
- Computer Systems Group, Department of Electrical Engineering and Information Technology, Technische Universität Darmstadt, Darmstadt, Germany
| | - T Oster
- Integrated Electronic Systems Lab, Department of Electrical Engineering and Information Technology, Technische Universität Darmstadt, Darmstadt, Germany
| | - K Hofmann
- Integrated Electronic Systems Lab, Department of Electrical Engineering and Information Technology, Technische Universität Darmstadt, Darmstadt, Germany
| | - J Suñé
- Departament d'Enginyeria Electrònica, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Valles, Spain
| | - E Miranda
- Departament d'Enginyeria Electrònica, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Valles, Spain
| | - L Alff
- Advanced Thin Film Technology Division, Institute of Materials Science, Technische Universität Darmstadt, Darmstadt, Germany
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Niu G, Schubert MA, Sharath SU, Zaumseil P, Vogel S, Wenger C, Hildebrandt E, Bhupathi S, Perez E, Alff L, Lehmann M, Schroeder T, Niermann T. Electron holography on HfO 2/HfO 2-x bilayer structures with multilevel resistive switching properties. Nanotechnology 2017; 28:215702. [PMID: 28462907 DOI: 10.1088/1361-6528/aa6cd9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Unveiling the physical nature of the oxygen-deficient conductive filaments (CFs) that are responsible for the resistive switching of the HfO2-based resistive random access memory (RRAM) devices represents a challenging task due to the oxygen vacancy related defect nature and nanometer size of the CFs. As a first important step to this goal, we demonstrate in this work direct visualization and a study of physico-chemical properties of oxygen-deficient amorphous HfO2-x by carrying out transmission electron microscopy electron holography as well as energy dispersive x-ray spectroscopy on HfO2/HfO2-x bilayer heterostructures, which are realized by reactive molecular beam epitaxy. Furthermore, compared to single layer devices, Pt/HfO2/HfO2-x /TiN bilayer devices show enhanced resistive switching characteristics with multilevel behavior, indicating their potential as electronic synapses in future neuromorphic computing applications.
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Affiliation(s)
- G Niu
- Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education & International Center for Dielectric Research, Xi'an Jiaotong University, Xi'an 710049, People's Republic of China. IHP, Im Technologiepark 25, D-15236 Frankfurt (Oder), Germany
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Zintler A, Kunz U, Pivak Y, Sharath SU, Vogel S, Hildebrandt E, Kleebe HJ, Alff L, Molina-Luna L. FIB based fabrication of an operative Pt/HfO 2/TiN device for resistive switching inside a transmission electron microscope. Ultramicroscopy 2017; 181:144-149. [PMID: 28558287 DOI: 10.1016/j.ultramic.2017.04.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 03/10/2017] [Accepted: 04/14/2017] [Indexed: 11/17/2022]
Abstract
Recent advances in microelectromechanical systems (MEMS) based chips for in situ transmission electron microscopy are opening exciting new avenues in nanoscale research. The capability to perform current-voltage measurements while simultaneously analyzing the corresponding structural, chemical or even electronic structure changes during device operation would be a major breakthrough in the field of nanoelectronics. In this work we demonstrate for the first time how to electrically contact and operate a lamella cut from a resistive random access memory (RRAM) device based on a Pt/HfO2/TiN metal-insulator-metal (MIM) structure. The device was fabricated using a focused ion beam (FIB) instrument and an in situ lift-out system. The electrical switching characteristics of the electron-transparent lamella were comparable to a conventional reference device. The lamella structure was initially found to be in a low resistance state and could be reset progressively to higher resistance states by increasing the positive bias applied to the Pt anode. This could be followed up with unipolar set/reset operations where the current compliance during set was limited to 400 µA. FIB structures allowing to operate and at the same time characterize electronic devices will be an important tool to improve RRAM device performance based on a microstructural understanding of the switching mechanism.
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Affiliation(s)
- A Zintler
- Technische Universität Darmstadt, Department of Material- and Geosciences, Alarich-Weiss-Strasse 2, 64287 Darmstadt, Germany
| | - U Kunz
- Technische Universität Darmstadt, Department of Material- and Geosciences, Alarich-Weiss-Strasse 2, 64287 Darmstadt, Germany
| | - Y Pivak
- DENSsolutions, Informaticalaan 12, 2628ZD, Delft, Netherlands
| | - S U Sharath
- Technische Universität Darmstadt, Department of Material- and Geosciences, Alarich-Weiss-Strasse 2, 64287 Darmstadt, Germany
| | - S Vogel
- Technische Universität Darmstadt, Department of Material- and Geosciences, Alarich-Weiss-Strasse 2, 64287 Darmstadt, Germany
| | - E Hildebrandt
- Technische Universität Darmstadt, Department of Material- and Geosciences, Alarich-Weiss-Strasse 2, 64287 Darmstadt, Germany
| | - H-J Kleebe
- Technische Universität Darmstadt, Department of Material- and Geosciences, Alarich-Weiss-Strasse 2, 64287 Darmstadt, Germany
| | - L Alff
- Technische Universität Darmstadt, Department of Material- and Geosciences, Alarich-Weiss-Strasse 2, 64287 Darmstadt, Germany
| | - L Molina-Luna
- Technische Universität Darmstadt, Department of Material- and Geosciences, Alarich-Weiss-Strasse 2, 64287 Darmstadt, Germany.
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Geck J, Zwiebler M, Gray B, Chakhalian J, Freeland J, He F, Koitzsch A, Komissinskiy P, Schierle E, Sutarto S, Treske U, Vafaee M, Weschke E, Sawatzky GA, Alff L, Macke S, Hamann-Borrero JE. Electronic depth profiles with atomic layer resolution from resonant X-ray reflectivity. Acta Crystallogr A Found Adv 2015. [DOI: 10.1107/s2053273315097545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Alff L, Krockenberger Y, Welter B, Schonecke M, Gross R, Manske D, Naito M. A hidden pseudogap under the 'dome' of superconductivity in electron-doped high-temperature superconductors. Nature 2003; 422:698-701. [PMID: 12700755 DOI: 10.1038/nature01488] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2002] [Accepted: 02/07/2003] [Indexed: 11/09/2022]
Abstract
The ground state of superconductors is characterized by the long-range order of condensed Cooper pairs: this is the only order present in conventional superconductors. The high-transition-temperature (high-T(c)) superconductors, in contrast, exhibit more complex phase behaviour, which might indicate the presence of other competing ground states. For example, the pseudogap--a suppression of the accessible electronic states at the Fermi level in the normal state of high-T(c) superconductors-has been interpreted as either a precursor to superconductivity or as tracer of a nearby ground state that can be separated from the superconducting state by a quantum critical point. Here we report the existence of a second order parameter hidden within the superconducting phase of the underdoped (electron-doped) high-T(c) superconductor Pr2-xCe(x)CuO4-y and the newly synthesized electron-doped material La2-xCe(x)CuO4-y (ref. 8). The existence of a pseudogap when superconductivity is suppressed excludes precursor superconductivity as its origin. Our observation is consistent with the presence of a (quantum) phase transition at T = 0, which may be a key to understanding high-T(c) superconductivity. This supports the picture that the physics of high-T(c) superconductors is determined by the interplay between competing and coexisting ground states.
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Affiliation(s)
- L Alff
- Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany.
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Alff L, Marx A, Gross R, Beck A, Takashima H, Kashiwaya S, Koyanagi M, Tanaka Y. Tunneling spectroscopy of high-Tc superconductors. ACTA ACUST UNITED AC 1999. [DOI: 10.1016/s0964-1807(99)00042-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Froehlich OM, Schulze H, Gross R, Beck A, Alff L. Precision measurement of the in-plane penetration depth lambda ab(T) in YBa2Cu3O7- delta using grain-boundary Josephson junctions. Phys Rev B Condens Matter 1994; 50:13894-13897. [PMID: 9975609 DOI: 10.1103/physrevb.50.13894] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Ri H, Kober F, Beck A, Alff L, Gross R, Huebener RP. Thermal diffusion of quasiparticles and vortices in the mixed state of high-temperature superconductors. Phys Rev B Condens Matter 1993; 47:12312-12315. [PMID: 10005414 DOI: 10.1103/physrevb.47.12312] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Baier U, Fischer R, Beck A, Koelle D, Blocher K, Alff L, Gross R. Flux motion in strained YBa2Cu3O7- delta /Nd1.83Ce0.17CuOx superlattices. Phys Rev B Condens Matter 1992; 46:11236-11239. [PMID: 10003008 DOI: 10.1103/physrevb.46.11236] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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