Low transition-temperature characteristic in VOx films grown on Si3N4/Glass substrates

VOx thin films grown on a borosilicate glass substrate with a Si3N4 buffer layer by reactive ion beam sputtering with the varying substrate temperature, argon and oxygen (Ar/O2) gas mixture ratio and annealing temperature are investigated. The XRD patterns show that the films are composed of different vanadium oxides, such as V2O3, VO2, V6O13 and V2O5. The electrical resistance tests indicate that the filmsʹ phase transition temperature rises (from 29 to 35 °C) as the substrate temperature increases (from 250 to 310 °C). Besides, change of the Ar/O2 gas mixture ratio has a huge impact on the filmsʹ transition temperature and switching efficiency. VOx thin films fabricated with an Ar/O2 gas mixture ratio of 60:20, 60:30 and 60:40 SCCM exhibit a phase transition feature at a temperature of 36, 30 and 32 °C, respectively. The VOx thin films show a phase transition character at a temperature of 35, 30 and 34 °C, respectively, as the annealing temperature increases from 400 to 460 °C with an increment of 30 °C. Additionally, the switching efficiency of sample 6 is the lowest owing to the annealing temperature which is too low to make the film oxidized completely.