Pulsed Laser and Atomic Layer Deposition of CMOS-Compatible Vanadium Dioxide: Enabling Ultrathin Phase-Change Films

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Vanadium dioxide (VO2) is a Mott insulator with significant potential in advanced electronics, including neuromorphic computing and smart windows.
• Fabricating high-performance polycrystalline VO2 films, especially ultrathin layers on silicon, presents challenges in achieving desired transport and switching characteristics.

Purpose of the Study:

• To investigate the growth dynamics of VO2 films on CMOS-compatible silicon substrates using Pulsed Laser Deposition (PLD) and Atomic Layer Deposition (ALD).
• To identify optimal growth parameters for producing ultrathin VO2 layers with functional properties for advanced gate applications.

Main Methods:

• Systematic characterization of VO2 films (200 nm down to <10 nm) grown by PLD and ALD on wet-oxidized silicon wafers.
• Structural and electrical analyses to determine the influence of growth parameters, specifically temperature and pressure, on film quality and switching performance.

Main Results:

• Temperature and pressure were identified as critical factors governing VO2 film morphology and switching behavior.
• Both PLD and ALD techniques were optimized to successfully produce ultrathin VO2 layers as thin as 6-8 nm.
• PLD yielded high-density films, while ALD provided conformal coating capabilities, demonstrating versatility for different applications.

Conclusions:

• Optimized growth parameters enable the fabrication of functional ultrathin polycrystalline VO2 films on silicon substrates using both PLD and ALD.
• This research highlights the feasibility of VO2 for fully CMOS-compatible phase-change switching devices.
• The study offers valuable insights for optimizing polycrystalline VO2 film growth across various deposition techniques.