Unveiling the Effect of Superlattice Interfaces and Intermixing on Phase Change Memory Performance

Asir Intisar Khan; Xiangjin Wu; Christopher Perez; Byoungjun Won; Kangsik Kim; Pranav Ramesh; Heungdong Kwon; Maryann C Tung; Zonghoon Lee; Il-Kwon Oh; Krishna Saraswat; Mehdi Asheghi; Kenneth E Goodson; H-S Philip Wong; Eric Pop

doi:10.1021/acs.nanolett.2c01869

Unveiling the Effect of Superlattice Interfaces and Intermixing on Phase Change Memory Performance

Nano Lett. 2022 Aug 10;22(15):6285-6291. doi: 10.1021/acs.nanolett.2c01869. Epub 2022 Jul 25.

Authors

Asir Intisar Khan¹, Xiangjin Wu¹, Christopher Perez², Byoungjun Won³, Kangsik Kim⁴, Pranav Ramesh¹, Heungdong Kwon², Maryann C Tung¹, Zonghoon Lee^{4

5}, Il-Kwon Oh³, Krishna Saraswat¹, Mehdi Asheghi², Kenneth E Goodson², H-S Philip Wong¹, Eric Pop^{1

6

7}

Affiliations

¹ Department of Electrical Engineering, Stanford University, Stanford, California 94305, United States.
² Department of Mechanical Engineering, Stanford University, Stanford, California 94305, United States.
³ Department of Electrical and Computer Engineering, Ajou University, Suwon 16499, Republic of Korea.
⁴ Center for Multidimensional Carbon Materials, Institute for Basic Science, Ulsan 44919, Republic of Korea.
⁵ Department of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea.
⁶ Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States.
⁷ Precourt Institute for Energy, Stanford University, Stanford, California 94305, United States.

PMID: 35876819
DOI: 10.1021/acs.nanolett.2c01869

Abstract

Superlattice (SL) phase change materials have shown promise to reduce the switching current and resistance drift of phase change memory (PCM). However, the effects of internal SL interfaces and intermixing on PCM performance remain unexplored, although these are essential to understand and ensure reliable memory operation. Here, using nanometer-thin layers of Ge₂Sb₂Te₅ and Sb₂Te₃ in SL-PCM, we uncover that both switching current density (J_reset) and resistance drift coefficient (v) decrease as the SL period thickness is reduced (i.e., higher interface density); however, interface intermixing within the SL increases both. The signatures of distinct versus intermixed interfaces also show up in transmission electron microscopy, X-ray diffraction, and thermal conductivity measurements of our SL films. Combining the lessons learned, we simultaneously achieve low J_reset ≈ 3-4 MA/cm² and ultralow v ≈ 0.002 in mushroom-cell SL-PCM with ∼110 nm bottom contact diameter, thus advancing SL-PCM technology for high-density storage and neuromorphic applications.

Keywords: Sb2Te3/Ge2Sb2Te5 superlattice; phase-change memory; resistance drift; superlattice interface; superlattice intermixing; switching current density.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.
Research Support, Non-U.S. Gov't

MeSH terms

Thermal Conductivity*
X-Ray Diffraction