Abstract
Vanadium dioxide (VO2) is a popular phase-transition material with broad applications ranging from thermal management in smart windows to neuromorphic computing. Currently, VO2 thin films are usually fabricated at high temperatures, making them incompatible in forming on top of CMOS and flexible polyimide substrates. This study explores a low-temperature VO2 thin film formation approach that combines atomic layer deposition (ALD) with a post-deposition anneal. With systematic material characterizations, we clearly demonstrate high-quality VO2 film formation on Si substrates at a significantly reduced annealing temperature of 300 °C. Further reducing the annealing temperature to 250 oC is shown to lead to insufficient VO2 crystallization whilst elevating the temperature to 400 oC results in overoxidation into V2O5. We implement our method on polyimide substrates and demonstrate that the high-quality phase transition is indeed preserved. This work demonstrates the ability of low-temperature formation of VO2 thin films, and it will accelerate the adoption of VO2 in emerging electronic devices as well as photonic applications.