PE-ALD of Ge1−xSxamorphous chalcogenide alloys for OTS applications

Myoungsub Kim, Youngjun Kim, Minkyu Lee, Seok Man Hong, Hyung Keun Kim, Sijung Yoo, Taehoon Kim, Seung Min Chung, Taeyoon Lee, Hyungjun Kim

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5 Citations (Scopus)


Three-dimensional (3D) cross-point (X-point) technology, including amorphous chalcogenide-based ovonic threshold switching (OTS) selectors, is bringing new changes to the memory hierarchy for high-performance computing systems. To prepare for future 3D X-point memory scaling, we studied the plasma-enhanced atomic layer deposition (PE-ALD) of Ge1−xSxamorphous chalcogenide alloy thin films, the selection of which was motivated by their high optical bandgap and wide amorphous forming regions. The PE-ALD Ge1−xSxthin films were synthesized using a GeCl4precursor and H2S plasma reactant, and their self-limited growth characteristics were studied in detail as a function of the exposure time of the ALD steps, temperature, and plasma power. The PE-ALD GeS2thin film showed an RMS roughness of 0.29 nm and good conformality in the vertical 3D structure. Moreover, the OTS behavior of GeS2and Ge2S3mushroom-type devices with a 50 nm bottom electrode contact (BEC) were investigated as well as the trade-off relationship between the threshold voltage (1.9-6.2 V) and the normalized off current (20-250 nA) based on scaling the film thickness down from 30 nm to 5 nm. In particular, the GeS2device showed a higher threshold field (∼3.1 MV cm−1) and lower normalized off current characteristics than the Ge2S3device due to the higher trap density (2.1 × 1021cm−3), according to the modified Poole-Frenkel (PF) model. The results achieved by this PE-ALD research on this novel binary GeS2amorphous chalcogenide for OTS applications will contribute to the development of future 3D cross-point memory scaling.

Original languageEnglish
Pages (from-to)6006-6013
Number of pages8
JournalJournal of Materials Chemistry C
Issue number18
Publication statusPublished - 2021 May 14

Bibliographical note

Funding Information:
This paper was result of the research project supported by SK Hynix Inc.

Publisher Copyright:
© The Royal Society of Chemistry 2021.

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Materials Chemistry


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