Magnesium- and fluorine co-doping of vanadium dioxide films

Thermochromic Mg- and F-doped VO2 thin films, which enable new possibilities as an intelligent window coating, were deposited by rf sputtering. The appliance of VO2 for energy efficient fenestration is so far limited by some properties of the bulk material. The alternation of luminous transmittance of bulk VO2, which is caused by a reversible metal-semiconductor phase transition, will appear at temperatures about 68 C. By doping with Mg or F this transition temperature can be decreased to practical values. Furthermore, the Mg-doping level is associated with a blue shift of the band gap energy and is connected with an increase of luminous transmittance.