Heterogeneous reservoir computing in second-order TaO/HfO memristors.
Nestor Ghenzi, Tae Won Park, Seung Soo Kim, Hae Jin Kim, Yoon Ho Jang, Kyung Seok Woo, Cheol Seong Hwang
Author Information
Nestor Ghenzi: Department of Materials Science and Engineering and Inter-University Semiconductor Research Center, Seoul National University Gwanak-ro 1, Gwanak-gu, Seoul 08826, Republic of Korea. kevinwoo@snu.ac.kr. ORCID
Tae Won Park: Department of Materials Science and Engineering and Inter-University Semiconductor Research Center, Seoul National University Gwanak-ro 1, Gwanak-gu, Seoul 08826, Republic of Korea. kevinwoo@snu.ac.kr.
Seung Soo Kim: Department of Materials Science and Engineering and Inter-University Semiconductor Research Center, Seoul National University Gwanak-ro 1, Gwanak-gu, Seoul 08826, Republic of Korea. kevinwoo@snu.ac.kr.
Hae Jin Kim: Department of Materials Science and Engineering, Myongji University, Yongin 17058, Korea.
Yoon Ho Jang: Department of Materials Science and Engineering and Inter-University Semiconductor Research Center, Seoul National University Gwanak-ro 1, Gwanak-gu, Seoul 08826, Republic of Korea. kevinwoo@snu.ac.kr.
Kyung Seok Woo: Department of Materials Science and Engineering and Inter-University Semiconductor Research Center, Seoul National University Gwanak-ro 1, Gwanak-gu, Seoul 08826, Republic of Korea. kevinwoo@snu.ac.kr. ORCID
Cheol Seong Hwang: Department of Materials Science and Engineering and Inter-University Semiconductor Research Center, Seoul National University Gwanak-ro 1, Gwanak-gu, Seoul 08826, Republic of Korea. kevinwoo@snu.ac.kr. ORCID
Multiple switching modes in a TaO/HfO memristor are studied experimentally and numerically through a reservoir computing (RC) simulation to reveal the importance of nonlinearity and heterogeneity in the RC framework. Unlike most studies, where homogeneous reservoirs are used, heterogeneity is introduced by combining different behaviors of the memristor units. The chosen memristor for the reservoir units is based on a TaO/HfO bilayer, in which the conductances of the TaO and HfO layers are controlled by the oxygen vacancies and deep/shallow traps, respectively, providing both volatile and non-volatile resistive switching modes. These several control parameters make the second-order TaO/HfO memristor system present different behaviors in agreement with its history-dependent conductance and allow the fine-tuning of the behavior of each reservoir unit. The heterogeneity in the reservoir units improves the pattern recognition performance in the heterogeneous memristor RC system with a similar physical structure.
