Rapid laser-induced low temperature crystallization of thermochromic VO2 sol-gel thin films

• Published in: Applied surface science Vol. 631; p. 157507
• Main Authors: Basso, Maria, Colusso, Elena, Carraro, Chiara, Kalha, Curran, Riaz, Aysha A., Bombardelli, Giada, Napolitani, Enrico, Chen, Yu, Jasieniak, Jacek, Ratcliff, Laura E., Thakur, Pardeep K., Lee, Tien-Lin, Regoutz, Anna, Martucci, Alessandro
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.09.2023
• Subjects: Laser; Photonic curing; Smart windows; Sol gel; Thermochromic; Vanadium oxide; Vanadium oxide; Photonic curing; Thermochromic; Smart windows; Laser; Sol gel
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2023.157507

[Display omitted] •VO2 thin film obtained by green sol–gel process.•VO2 crystallization induced by pulsed excimer laser within 1 min irradiation in air.•Influence of laser pulses and laser fluence on film’s properties was systematically studied.•Threshold laser parameters to induce VO2 crystallization without surface melting were found.•Thermochromic performance of laser-annealed thin films was comparable to reference furnace-annealed samples. The thermochromic properties of vanadium dioxide (VO2) offer great advantages for energy-saving smart windows, memory devices, and transistors. However, the crystallization of solution-based thin films at temperatures lower than 400°C remains a challenge. Photonic annealing has recently been exploited to crystallize metal oxides, with minimal thermal damage to the substrate and reduced manufacturing time. Here, VO2 thin films, obtained via a green sol–gel process, were crystallized by pulsed excimer laser annealing. The influence of increasing laser fluence and pulse number on the film properties was systematically studied through optical, structural, morphological, and chemical characterizations. From temperature profile simulations, the temperature rise was confirmed to be confined within the film during the laser pulses, with negligible substrate heating. Threshold laser parameters to induce VO2 crystallization without surface melting were found. With respect to furnace annealing, both the crystallization temperature and the annealing time were substantially reduced, with VO2 crystallization being achieved within only 60 s of laser exposure. The laser processing was performed at room temperature in air, without the need of a controlled atmosphere. The thermochromic properties of the lasered thin films were comparable with the reference furnace-treated samples.