Related Experiment Video
Updated: Jun 6, 2025
11:10
Atomic Layer Deposition of Vanadium Dioxide and a Temperature-dependent Optical Model
Published on: May 23, 2018
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Subpicosecond Spectroscopic Ellipsometry of the Photoinduced Phase Transition in VO2 Thin Films
Yael Gutiérrez1,2, Saúl Vázquez-Miranda3, Shirly Espinoza3
1Departamento de Física Aplicada, Universidad de Cantabria, Avenida de los Castros, s/n, 39005 Santander, Spain.
ACS Photonics
|November 25, 2024
Summary
We used ultrafast pump-probe ellipsometry to study the insulator-to-metal transition (IMT) in vanadium dioxide (VO2) thin films. This revealed distinct nonthermal dynamics and differences in phase transition pathways within the first picosecond.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Ultrafast Spectroscopy
Background:
- Vanadium dioxide (VO2) exhibits a critical insulator-to-metal transition (IMT) with significant potential for photonic devices.
- Understanding the ultrafast dynamics of this photoinduced IMT is crucial for controlling VO2-based technologies.
- Previous studies lacked the temporal resolution to fully capture the initial stages of the photoinduced IMT.
Purpose of the Study:
- To apply broadband time-resolved pump-probe ellipsometry for the first time to investigate ultrafast dynamics of photoinduced IMT in VO2.
- To directly measure the time-resolved evolution of the complex pseudodielectric function during the VO2 IMT.
- To differentiate between thermal and nonthermal dynamics and elucidate the primary differences in IMT pathways.
Main Methods:
- Utilized 35 fs laser pulses for pump-probe excitation of VO2 thin films.
- Employed broadband time-resolved pump-probe ellipsometry to monitor changes in the complex pseudodielectric function.
- Analyzed the temporal and spectral phase evolution during the photoinduced IMT.
Main Results:
- Successfully measured the time-resolved evolution of the complex pseudodielectric function of VO2 during photoinduced IMT.
- Identified distinct thermal and nonthermal dynamics, dependent on pump wavelength and fluence.
- Revealed that primary differences between thermal and photoinduced IMT pathways occur within the first picosecond, driven by nonthermal, nonequilibrium dynamics.
Conclusions:
- Broadband time-resolved pump-probe ellipsometry is a powerful technique for studying ultrafast phase transitions.
- Nonthermal dynamics play a critical role in the initial picosecond of the photoinduced IMT in VO2.
- The study provides a detailed temporal and spectral map of the VO2 IMT, offering insights for photonic device applications.
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