Abstract
Metal oxide thin-film materials are currently employed to perform technologically advanced
functions in a wide range of applications. This thesis reports on thermochromic VO2 and the phases
of TiO2 that have smart window applications and for which deposition of crystalline material onto
temperature-sensitive substrates such as plastics is challenging. The oxide films were deposited by
reactive remote plasma sputtering (RPS), characterised by XRD, SEM, XPS and their optical and
electrical properties recorded. Vanadium oxide (VOx) films were studied using a metallic-like reactive
sputtering regime with unheated, heated, and radiofrequency-biased substrate conditions, but in
each case crystalline thermochromic VO2 was not achieved. Crystalline phases of V, cubic VO, and
V2O3 were deposited onto unheated substrates. Substrate heating (320 and 350 °C) promoted the
growth of crystalline V2O3 and V2O5. Crystalline thermochromic VO2 was also not grown using a
ceramic target using quasi-reactive sputtering or post-deposition annealing. Variation of the
deposition rate and substrate biasing power/voltage were parameters explored for reactive RPS
deposition of transparent titanium oxide (TiOx) films from a metallic Ti target. Pure rutile was
observed using an rf substrate bias voltage > 41 V. The highest refractive index was found when
employing the slowest deposition rate (1.8 nm min⁻1). Further increase of the substrate bias voltage
caused the rutile texture to change from low-energy [110]-preferred orientation to high-energy
[101]- and [002]-preferred orientation. Film stress was found to be mainly influenced by the
substrate bias voltage. A comparison of the current–voltage (I–V) characteristics and sputter yield
behaviour of reactive RPS and magnetron sputtering films was performed by examining the
literature and characterisation results. A different I–V regime to magnetron sputtering was found for
RPS which was not heavily dependent on the work function of the target material with possible
mechanisms and implications for reactive RPS processes discussed.