An innovative method to achieve large-scale high-quality VO2 thin films: Oxidation of vanadium nitride material deposited by sputtering

Depositing high-quality VO2 thin films on a large area has been challenging till date. While magnetron sputtering is widely used for this type of deposition, it faces serious reproducibility issues for VO2 films due to target poisoning. In this work, we present an improved technique called sputtering oxidation coupling (SOC) using VN as intermediate material. VN films are first deposited on quartz by magnetron sputtering. In a second step, a post -annealing process in oxygen is carried out to obtain VO2. For an annealing temperature of 470 degrees C, 0.5 h of oxidation under an oxygen pressure of 70 mTorr yields VO2 films with the best performance in terms of transition properties. While the resistivity contrast has a magnitude of 2.9, the transmittance contrast is 69.3%. This is comparable to VO2 films produced by Pulsed Laser Deposition (PLD), which is well recognized for its capability to provide high-quality VO2 thin films. Furthermore, the lowest possible temperature for achieving VO2 from VN with an acceptable electrical transition contrast (2.5) is found to be 400 degrees C, which makes the proposed method promising for growing VO2 films directly on heat-sensitive polymer substrates.

Automated summary

Depositing high-quality VO2 thin films on a large area has been a challenge. This study presents an improved technique called sputtering oxidation coupling (SOC) using VN as intermediate material. VN films are first deposited on quartz by magnetron sputtering and then annealed in oxygen to obtain VO2 films with good performance in terms of transition properties. The proposed method is comparable to Pulsed Laser Deposition (PLD) in producing high-quality VO2 films.