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

TL;DR

This paper studies how to grow ultrathin vanadium dioxide films using two techniques, showing they can be made compatible with silicon electronics.

Contribution

The study identifies optimal growth conditions for ultrathin VO2 films using PLD and ALD for CMOS compatibility.

Findings

PLD and ALD can produce functional ultrathin VO2 films as small as 6–8 nm.

Temperature and pressure are key factors affecting film morphology and switching performance.

Both methods enable CMOS-compatible VO2 films suitable for advanced electronics.

Abstract

Vanadium dioxide
(VO2), a well-known Mott insulator,
is a highly studied electronic material with promising applications
in information processing and storage, including neuromorphic and
brain-inspired electronics, high-frequency reconfigurable electronics,
optoelectronic modulators, sensors, and smart windows with thermal
regulation. While epitaxial VO2 layers exhibit exceptional
properties, such as a sharp and abrupt conductivity change at the
metal–insulator transition, fabricating polycrystalline VO2 films on silicon substrates often involves trade-offs in
transport characteristics and switching performance, especially for
ultrathin layers required in advanced gate applications. In this study,
we explore the growth dynamics of VO2 films on standard
CMOS-compatible wet-oxidized silicon wafers by using two established
deposition techniques: pulsed laser deposition (PLD) and atomic layer
deposition (ALD). VO2 films, ranging in thickness from
200 nm to less than 10 nm, were systematically characterized through
structural and electrical analyses to optimize key growth parameters.
In this study, the temperature and pressure were identified as the
key factors influencing the morphology and quality of switching in
VO2 films. The growth dynamics and optimal growth conditions across
the entire thickness range are discussed in detail. PLD and ALD offer
distinct advantages: PLD enables the formation of high-density films,
while ALD allows for conformal deposition on complex 3D structures.
We demonstrate that both methods can successfully produce ultrathin
VO2 layers down to 6–8 nm with functional properties
suitable for practical applications, provided that growth parameters
are carefully optimized. This work underscores the potential of VO2 for fully CMOS-compatible phase-change switching devices
and provides valuable insights into optimizing growth processes for
polycrystalline VO2 films grown with different techniques,
including widely used magnetron sputtering.

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