Modulation of insulator metal transition of VO₂ films by the crystallization of capping GST layer

What is it about?

Modulation of insulator metal transition (IMT) of vanadium dioxide (VO2) films with crystallization of capping chalcogenide GST layer was demonstrated. The chalcogenide germanium- antimony-telluride (Ge2Sb2Te5: GST) shows large volume reduction of 6.8% with its phase change from amorphous to crystal. Thus, crystallization of GST film on VO2 films results in lattice length change between V-V atoms of the VO2 film, which is parallel to the Al2O3 (001) single crystalline substrate. We also introduced VO2 film grown on TiO2 (001) substrate, where direction of V-V chains is perpendicular to the TiO2 (001) substrate, hence crystallization of GST resulted in counter shift of IMT of VO2 films. The obtained results open a way to realize large resistance change of IMT under constant temperature by controlling GST phases.

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Photo by JJ Ying on Unsplash

Photo by JJ Ying on Unsplash

Why is it important?

Vanadium dioxide is known as phase transition compound which shows insulator metal transition (IMT) with large resistance change over three orders of magnitudes at around 68 °C. However, this IMT is volatile characteristic, where resistance shows reversible change with temperature change. This study focuses on shift of IMT temperature by the strong compression by capped GST layer on the VO2 films grown on single crystalline substrates. Observed shift of the IMT by crystallization of GST layer suggests possibility of nonvolatile resistance change with the change of GST between amorphous and crystalline states.

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