Effect of Oxygen Deposition Pressure on the Structure and the Metal Insulator Transition in Pulsed Laser Deposited VO<SUB>2</SUB> Films on Soda Lime Glass

Abstract

Vanadium dioxide thin films nanostructures were synthesized by pulsed laser deposition on soda lime glass at a substrate temperature of 600°C and the effects of the oxygen deposition pressure on the crystalline structure and the phase transition characteristics of VO 2 nanostructured films were investigated. The structure and microstructure of the films have been examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results indicate that the crystal structure of the films is strongly sensitive to the oxygen deposition pressure; exhibiting sharp a-axis diffraction peaks, showing a texturation along (1 0 0) plane. A detailed description of the growth mechanisms and the substrate-film interaction is given, and the characteristics of the electronic transition and hysteresis of the phase transition are described in terms of the morphology, grain boundary structure and crystal orientation. The sharpness of the transition and the hysteresis upon heating and cooling are found to be strong functions of the crystal structure and microstructure (grain size). Keywords:

Characterization of the VO2 thin films grown on glass substrates by MOD

“…In the films deposited on glass substrates, O1s peaks are split in two, while positions of V2p 1/2 and V2p 3/2 peaks are shifted toward high energies. The split of O1s peaks can be attributed to CaCO 3 (531.3 eV) or Na 2 CO 3 (531.8 eV) 3,15 . In addition, V2p 1/2 and V2p 3/2 peaks intensified with higher Nb concentration, and V2p 3/2 peak split in two, same as O1s peak.…”

“…The split of O1s peaks can be attributed to CaCO 3 (531.3 eV) or Na 2 CO 3 (531.8 eV). 3,15 In addition, V2p 1/2 and V2p 3/2 peaks intensified with higher Nb concentration, and V2p 3/2 peak split in two, same as O1s peak. On the other hand, in the films deposited on HZO layer, position of O1s peak is almost same as in Nb-doped stoichiometric VO 2 films, while positions of V2p 1/2 and V2p 3/2 peaks are shifted toward high energies.…”

“…2 However, there a few reports on polycrystalline stoichiometric VO 2 films deposited on a glass substrate and on reduction of phase transition temperature, while such windows in buildings and vehicles have not been realized. This is because soda-lime glass used widely for windows is made mainly of silicon oxide (SiO 2 ), soda ash (Na 2 O), and lime (CaO), thus having a low melting point; when temperature reaches that of VO 2 deposition (over 500 • C), a slight stoichiometric deviation occurs, while Al, Na, or Ca diffuse to from glass substrates to films to be partially oxidized 3 ; thus, polycrystalline stoichiometric VO 2 films are extremely hard to obtain.…”