Undoped InOx Films Deposited by Radio Frequency Plasma Enhanced Reactive Thermal Evaporation at Room Temperature: Importance of Substrate.
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Conductive and transparent undoped thin films of indium oxide (InO(x)), 120 nm average thick, were deposited by radio frequency plasma enhanced reactive thermal evaporation (rf-PERTE) of indium in the presence of oxygen at room temperature. Several substrates were used in order to study their influence on the main properties of these films: alkali free (AF) glass, fused silica, crystalline silicon and polyethylene terephthalate (PET). Surface morphology of the InO(x) films as a function of the substrates was observed by SEM and showed that the undoped InO(x) films obtained are nano-structured. For the c-Si substrate, InO(x) films with increased grain size are obtained, induced by the crystalline substrate. Films deposited on fused silica and AF glass substrates show a nano-grainy surface with similar surface morphologies. The InO(x) films deposited on AF glass show the highest values of both: electrical conductivity of about 1100 (Omega cm)(-1) and visible transmittance of 85%. The substrate has a greater influence on the surface morphology of the films when a polymer (PET) is used. InO(x) films deposited on PET show a decrease in the electrical conductivity (90 (Omega cm)(-1)) and a slight decrease in the average visible transmittance (78%).