Influence of postdeposition temperature treatment on surface morphology of vanadium oxide grown by ion-beam sputter deposition

Within the plethora of different vanadium oxide phases, vanadium dioxide (VO2) is a well-studied material for thermochromic applications such as smart windows. To obtain crystalline VO2 thin films, usually high in situ substrate temperatures are necessary. This, in turn, is detrimental on industrial scales, hence, alternatively postgrowth temperature treatment is a viable option. Even so, the surface morphology and roughness of the thin films exhibit strong temperature dependence. As these characteristics directly govern the physical, optical, and electronic responses, precise control of surface morphology—while maintaining phase stability—is vital. This is even more critical in multilayer architectures, where surface morphology influences the multilayer’s interfaces. Here, we use ion-beam sputter deposition for the reproducible growth of vanadium oxide and assess a variety of annealing procedures to manipulate both the surface and phase of the material. We show that the surface morphology as well as the phase transition depend on the annealing parameters, such as atmosphere, pressure, temperature, and duration of the chosen treatment.