VO2 THIN-FILMS - GROWTH AND THE EFFECT OF APPLIED STRAIN ON THEIR RESISTANCE

In this paper we report the synthesis and properties of various vanadi um oxide phases. Thin films have been prepared using conventional puls ed laser deposition (PLD). We have used both metallic V and ceramic V2 O5 targets to obtain the films. With both targets we have found that i t is possible to move, in a controlled way, through several of the oxi de states by changing the background oxygen gas pressure during deposi tion. Significantly, over the range of deposition conditions investiga ted we only observe the occurrence of the VO2, V6O13 and V2O5. This ob servation is unusual because as many as thirteen oxidation states are believed to exist. The temperature and strain dependence of film resis tance was also investigated. VO2 films were found to undergo their met allic to semiconducting phase transition at similar to 68 degrees C. T he resistance change across this transition was found to be greater th an four orders of magnitude. Further, in-plane tensile strains of 0.04 % were observed to change resistance values by similar to 35% near the phase transition. (C) 1998 Chapman & Hall.