April 22 - 26, 2024
Seattle, Washington
May 7 - 9, 2024 (Virtual)
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SB03.10.05

Revealing Oxygen Donor Level in Tungsten Oxide Films for Neuromorphic Applications with Parallel Dipole-Line Hall System

When and Where

Apr 25, 2024
11:45am - 12:00pm
Room 436, Level 4, Summit

Presenter(s)

Co-Author(s)

Hyunjeong Kwak1,Chaeyoun Kim2,Byungha Shin2,Oki Gunawan3,Seyoung Kim1

Pohang University of Science and Technology1,Korea Advanced Institute of Science and Technology2,IBM T.J. Watson Research Center3

Abstract

Hyunjeong Kwak1,Chaeyoun Kim2,Byungha Shin2,Oki Gunawan3,Seyoung Kim1

Pohang University of Science and Technology1,Korea Advanced Institute of Science and Technology2,IBM T.J. Watson Research Center3
Electrochemical random-access memory (ECRAM) devices stand as key candidates for realizing analog cross-point array-based AI computation accelerators thanks to its excellent programmability driven by ion movement, high stability, low cycle-to-cycle and device-to-device variation<i>(1)</i>. However, there have been limited efforts to investigate fundamental physical parameters of the key channel material, WO<sub>3-x</sub>, that control ECRAM switching characteristics. Tungsten oxide serves as a channel layer since its conductivity can be modulated depending on the ion concentration, rendering it a fitting choice to realize the analog switching<i>(2)</i>. In this work, we fabricate ECRAM devices in a multi-terminal Hall-bar structure and conduct Parallel Dipole Line (PDL) Hall measurements to investigate the essential electrical properties of tungsten oxide films, including resistivity, mobility, carrier density and activation energy. The AC Magnetic PDL Hall system, based on strong magnetic field generation and lock-in detection, offers high sensitivity, allowing for sensing even weak Hall signals from low mobility and high resistivity samples<i>(3)</i>. Furthermore, we measure the mobility and carrier density of tungsten oxide as a function of temperature using variable temperature PDL Hall measurements. The observed Hall mobility in WO<sub>3-x</sub> films reaches to 4.66 cm<sup>2</sup>/Vs at room temperature. At lower temperatures, a slight decrease in Hall mobility is observed due to impurity scattering from ionized centers. We extract the activation energy of the oxygen donor level in tungsten oxide thin films using Arrhenius plots. Our findings show the experimental access of the key variables that change during switching in ECRAM, which is not only crucial for enhancing ECRAM's performance but also essential for providing vital insights into neuromorphic applications.<br/><br/>1. P. Chen, F. Liu, P. Lin, P. Li, Y. Xiao, B. Zhang, G. Pan, Open-loop analog programmable electrochemical memory array. <i>Nature Communications</i> <b>14</b>, (2023).<br/>2. K. Miyake, H. Kaneko, Y. Teramoto, Electrical and optical properties of reactively sputtered tungsten oxide films. <i>Journal of Applied Physics</i> <b>53</b>, 1511-1515 (1982).<br/>3. O. Gunawan, S. R. Pae, D. M. Bishop, Y. Virgus, J. H. Noh, N. J. Jeon, Y. S. Lee, X. Shao, T. Todorov, D. B. Mitzi, B. Shin, Carrier-resolved photo-Hall effect. <i>Nature</i> <b>575</b>, 151-155 (2019).

Keywords

Hall effect | oxide | sputtering

Symposium Organizers

Dimitra Georgiadou, University of Southampton
Paschalis Gkoupidenis, Max Planck Institute
Francesca Santoro, Forschungszentrum Jülich/RWTH Aachen University
Yoeri van de Burgt, Technische Universiteit Eindhoven

Session Chairs

Paschalis Gkoupidenis
Jonathan Rivnay

In this Session