Stress-induced in situ modification of transition temperature in vo2 films capped by chalcogenide

Joe Sakai, Masashi Kuwahara, Kunio Okimura, Yoichi Uehara

Research output: Contribution to journalArticlepeer-review

Abstract

We attempted to modify the monoclinic–rutile structural phase transition temperature (Ttr) of a VO2 thin film in situ through stress caused by amorphous–crystalline phase change of a chalcogenide layer on it. VO2 films on C-or R-plane Al2 O3 substrates were capped by Ge2 Sb2 Te5 (GST) films by means of rf magnetron sputtering. Ttr of the VO2 layer was evaluated through temperature-controlled measurements of optical reflection intensity and electrical resistance. Crystallization of the GST capping layer was accompanied by a significant drop in Ttr of the VO2 layer underneath, either with or without a SiNx diffusion barrier layer between the two. The shift of Ttr was by ~30 C for a GST/VO2 bilayered sample with thicknesses of 200/30 nm, and was by ~6 C for a GST/SiNx /VO2 trilayered sample of 200/10/6 nm. The lowering of Ttr was most probably caused by the volume reduction in GST during the amorphous–crystalline phase change. The stress-induced in in situ modification of Ttr in VO2 films could pave the way for the application of nonvolatile changes of optical properties in optoelectronic devices.

Original languageEnglish
Article number5541
Pages (from-to)1-11
Number of pages11
JournalMaterials
Volume13
Issue number23
DOIs
Publication statusPublished - 2020 Dec

Keywords

  • Chalcogenide
  • Insulator-metal phase transition
  • Phase change material
  • Strain engineering
  • Vanadium oxide

ASJC Scopus subject areas

  • Materials Science(all)

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