Investigation of the metal-to-insulator transition of N-doped VO2(M1) thin films

• Published in: Applied surface science 2021-07, Vol.554, p.149661, Article 149661
• Main Authors: Chouteau, Simon, Mansouri, Sabeur, Mohamedou, Mohamed Lemine Ould Ne, Chaillou, Jérémie, Suleiman, Aminat Oyiza, Drogoff, Boris Le, Chaker, Mohamed
• Format: Article
• Language: English
• Subjects: Condensed Matter; Electrical and optical properties; Energy band gap; Laser deposition; Materials Science; N-doped VO2 (M1) thin films; Physics; Raman spectroscopy; Volume fraction calculations
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2021.149661

[Display omitted] •Pulsed laser deposition synthesis of nitrogen-doped VO2 films from a VN target.•Phase transition of N:VO2 is studied by Raman, electrical and infrared measurements.•The transition temperature is reduced to 50 °C at a doping percentage of 0.7 at%.•The structural, electrical and optical changes in N:VO2 show a strong correlation.•Volume fraction calculations give an insight into the phase transition of N:VO2. This work reports the effect of nitrogen doping on the electrical and optical properties of VO2 thin films. An innovative method based on a VN target and an O2 ambient gas was used to synthesize N:VO2 films on quartz substrates using reactive pulsed laser deposition (RPLD). The doping percentage was determined by elastic recoil distribution (ERD) measurements, while temperature-dependent Raman spectroscopy as well as electrical resistivity and infrared reflectance measurements were performed to investigate the effect of N-doping on the insulator monoclinic-to-metallic tetragonal phase transition (IMT) of VO2. A small doping percentage around 0.7 at.% was achieved, inducing a decrease of the transition temperature TIMT from 68 °C to 50 °C, with slightly reduced electrical contrast ΔR and optical contrast ΔA. By comparing the volume fraction of monoclinic phase, obtained from Raman data to the volume fraction of metallic phase deduced concurrently from both electrical and optical measurements, the IMT in our nitrogen-doped VO2 films occurs through a percolation process.